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Here is a small collection of frequently asked questions about driveshafts and driveline related items. Look over the list and hopefully it will help you with your problem. Unfortunately we cannot address every question here on this page and there may still be some unanswered questions that you may have. If you have something that is not answered her please see our Contact Us Page and fill our the form with your info. We will answer as soon as possible.
How much driveline angle is right for my application?
Is driveshaft balance really necessary?
Why is the number on my part different than the part number on the box?
What is available for my Diesel pick up truck?
I recently had a 3 inch exhaust system installed on my car and now I do not have much clearance for the driveshaft. What is the smallest diameter driveshaft that I can use that will handle the horsepower and weight of my vehicle?
I don't know which driveshaft to choose...can you help?
How much slip travel should I have?
EBAY PURCHASES....How much will I save if I buy a new slip yoke on ebay and send it to you to install onto my new driveshaft?
Why does the rear u-joint fit loosly in the pinion yoke?
How tight should I tighten my u-bolts?
Why does my rear u-joint wear out so often?
Can I order a driveshaft without a transmission slip yoke?
Can I order a driveshaft without u-joints?
Why did my driveshaft tubing twist or break?
My driveshaft is too short. Can I put on a longer slip yoke to make it fit better?
My driveshaft is too short. Can you add a little tubing to it to make it longer?
How tight should I tighten the grease fitting on a universal joint?
Do you offer driveshafts or driveline parts for Import cars and trucks?
How often should I add grease to my non greaseable u-joints?
How often should I grease my greaseable u-joints?
Do I have to measure to order a driveshaft?
Can I send in my driveshaft so you can use it for a template?
How much of a mistake am I allowed in my measurements?
I want to order a driveshaft but my car is all apart?
Is it called a Double Cardigan or is it a Double Cardan?
Is it called a Spleen or a Spline?
Is it Dana Splicer or Dana Spicer?
How do you say the company name "NEAPCO"?
What forms of payment do you accept?
How do I go about returning a part?
What is the difference between , and Series?
When is it necessary to upgrade to series?
What is the difference between the Chrysler and series?
What is General Motors 3R Series?
My slip yoke has a space where it appears that one spline is missing.
Why do I continue to break u-joints?
My transmission slip yoke feels like it is binding inside my transmission?
Does having urethane or solid mounts cause more driveline noise to be felt and heard while driving or racing?
How much driveline angle is right for my application?
Thats a loaded question. The best answer is....the least amount of driveline or u-joint angle is the best amount of angle. Try to achieve the least amount of u-joint angle but don't make it less than 1 degree. A little known fact about u-joints is that they require about 1 degree of operating angle to get the needle bearings rotating. If they do not rotate they will fail. Too much angle will also cause them to fail. The type of rear suspension also plays a big part in setting the angles as well as the engine/transmission angle. Leaf spring cars have a need for more downward pinion angle due to spring wrap-up while coil spring cars control the situation better. Hard acceleration as in the case of a drag race car requires a different setting than a street driven car. Traction bars, ladder bars, 4 links, independent rears all have special needs and requirements.
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Is driveshaft balance really necessary?
YES! Driveshaft balance is necessary for smooth driveline operation and to eliminate the destructive effects that an unbalanced or poorly balanced driveshaft will have on your transmission and rear end. At Denny's Driveshafts we High Speed High RPM Balance every driveshaft to meet or exceed the top rpm requirements of your engine and transmission, especially in the case of an overdrive transmission where the driveshaft rpm is greater than the engine rpm in high gear. This is very important and should not be overlooked when purchasing a new driveshaft. We can balance and test to 10,000 rpm so whatever your requirements are we can meet them. This will ensure that you will have the smoothest ride at all road speeds and track speeds and also a quicker ET. You won't be limited by rear end gear ratio and you will experience smooth running especially when using an overdrive transmission. True high speed balance means balancing at a High RPM.
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Why is the number on my part different than the part number on the box?
What you are seeing is the casting or forging number for the base part. These numbers are typically found on slip yokes, weld yokes, flange yokes, double cardan stud yokes and "h" yokes and many more parts. Most often if the part is a "casting" it will have a number that starts with a "C" and if it is a forging then it will start with an "F". This most often is never the actual part number because the factory may make many different part numbers from one base casting or forging. It is a smart way for the manufacturers to cut costs on similar parts. So when you see the number on the yoke does not match the number on the box...don't panic. It's not supposed to match!
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What is available for my Diesel pick up truck?
At this time we do not offer driveshafts in the series for diesel pick up trucks. We do, however, offer and Spicer universal joints to replace your originals. Some diesel pick up trucks whether 2wd or 4wd require series to handle the horsepower and torque output of todays high performance diesels. We will offer custom built series driveshafts in the future but at this time we do not.
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I recently had a 3 inch exhaust system installed on my car and now I do not have much clearance for the driveshaft. What is the smallest diameter driveshaft that I can use that will handle the horsepower and weight of my vehicle?
This is a common and growing problem that we hear about more often than we ever did before. You should always have the driveshaft built before the exhaust system to avoid all of these problems. The high horsepower cars and trucks that need a 3 inch exhaust system also need a strong driveshaft. Unfortunately the tunnel does not always allow for the proper size driveshaft and the 3 inch pipes to all fit into the same space. Some high horsepower cars can use a 3 inch diameter driveshaft with no problems but others may require a 3.5 inch or a 4 inch and now it won't fit with the large diameter pipes. Length is a big factor in the proper selection of driveshaft tube diameter. The long wheelbase cars cannot use a 3 inch driveshaft due to length, rpm and critical speed issues but a short wheelbase car can use a 3 inch or a 3.5 inch if the space allows. Driveshaft critical speed is not a problem with shorter overall lengths. The advice here is to be sure that your exhaust system installer makes room for the 3.5 inch diameter as a minimal choice for a driveshaft tube diameter. Some of you with long wheelbase vehicles may in fact need a 4 inch driveshaft... so be sure to let the installer know what you may need before he begins the work. Better yet...get the new driveshaft first!
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I don't know which driveshaft to choose...can you help?
Yes we will be happy to help you make the right driveshaft choice but first we will need to know the dimensions of your application and also more information about the vehicle. Please select the appropriate measuring diagram for your vehicle and print it out so that you can have it with you under the vehicle as you do the measuring. After you have measured please or call with those dimensions so that we can accurately recommend which driveshaft will be best for your vehicle. Click here to find the right diagram.
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How much slip travel should I have?
In most applications the minimum is 3/4 inch and more than 1 inch is not necessary. This is measured with the rear suspension supported on safety stands or with the rear end on the ground.
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EBAY PURCHASES....How much will I save if I buy a new slip yoke on ebay and send it to you to install onto my new driveshaft?
You may not save anything and in fact it may cost you more to do it that way. All Denny's Driveshafts are priced as a complete package. The cost of the slip yoke is factored in at an amount that is less than what you would pay to buy it separately. If you bid for the slip yoke on an ebay auction or if you select it as a "buy it now", your cost plus shipping it to you and then shipping it to us is almost always going to be more than it would have been if we had supplied the whole driveshaft including the slip yoke. The only way that it may save you money is if you purchased an expensive chrome moly slip yoke and paid less than half of what it normally sold for. Please call for the adjusted cost if you have a slip yoke you want us to use on your order.
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Why does the rear u-joint fit loosly in the pinion yoke?
A common mistake that is made when measuring is to measure the rear u-joint caps instead of measuring the pinion yoke. This is most common on Ford rear ends where a 1 1/8 inch cap diameter is found at the yoke saddles. Unfortunately someone has installed a u-joint with 1 1/16 inch caps. Always measure the pinion yoke.
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How tight should I tighten my u-bolts?
series and series should be tightened to 17 ft/lbs and series to 20 ft/lbs. You should never tighten the nuts on any u-bolt excessively. This will cause the cap to distort and the u-joint will fail prematurely.
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Why does my rear u-joint wear out so often?
This is usually the case when a u-bolt style pinion yoke is used. The pinion yoke is not the problem the overtightening of the u-bolt is the cause of the failure. You may find that every time you change the damaged rear u-joint you will find that one or both of the journals or caps that are under the u-bolts are destroyed and the ones that are pressed into the shaft are still in good shape. You did it to yourself! 17 ft/lbs for & series and 20 ft/lbs on the series. Click to see Photo
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Can I order a driveshaft without a transmission slip yoke?
Yes. We will need your slip yoke to balance your driveshaft correctly.
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Can I order a driveshaft without u-joints?
No. We cannot build and balance a driveshaft correctly without u-joints.
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Why did my driveshaft tubing twist or break?
There are many reasons. If you are using a stock driveshaft in a racing application then you already know the answer. Stock shafts should never be used for racing. If you had a driveshaft built by a driveline shop and it has broken or twisted the tubing then you should take it back to where you bought it. They apparently built your driveshaft with tubing that was similar to stock driveline tubing or possibly selected a tube diameter or thickness that was not correct for your application. Just because the shop builds dump truck shafts does not mean it can handle the requirements of a race car.
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My driveshaft is too short. Can I put on a longer slip yoke to make it fit better?
This is a common problem and many times this seems like an inexpensive way to make it fit better but this type of fix should be avoided. We never recommend installing a longer slip yoke when the shaft is actually too short for the application. Some transmission slip yokes are available with a longer barrel but they were designed longer for a specific application and not for the purpose of extending a shaft. Using one on a driveshaft that is actually too short for the application can lead to vibration and output shaft bushing failure. In extreme cases the internal spline can twist and bind up the slip movement. Don't do it!
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My driveshaft is too short. Can you add a little tubing to it to make it longer?
No. The correct way to lengthen a driveshaft is to remove both weld yokes and install a new tube of the proper length.
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How tight should I tighten the grease fitting on a universal joint?
Seems like a dumb question but actually it is a very good question. This is a question that should be asked more often but is almost never asked until someone breaks the grease fitting off in the u-joint. You don't need to tighten the fitting as if you were tightening lug nuts!!!! These things can break and they will break if tightened too much. The question now is how much?? We use a simple nut driver (looks like a screw driver with a socket on the end) to install and tighten grease fittings. No ratchets, no breaker bars, no impact guns. You DO NOT NEED much more than a snug fit and that fitting will stay put for a million miles. The threads on the fitting are tapered like a pipe thread so it is going to put up some resistance as you screw it in. There is absolutely NO GOOD REASON to bury that fitting into the u-joint by tightening it until the hex on the fitting comes in contact with the u-joint body. Don't do it because it will break!!! Remember a hand tight snug fit and you're done. There will be some threads exposed and that is perfectly acceptable. Enough said!
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Do you offer driveshafts or driveline parts for Import cars and trucks?
At this time we do not offer driveshafts or driveline parts for Imports. We may, however, offer them at a later date. When we do it will be posted on our home page.
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How often should I add grease to my non greaseable u-joints?
Never! Just leave them alone and they will last for a very long time. You can do more harm than good by taking them apart.
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How often should I grease my greaseable u-joints?
Greaseable u-joints should be greased every miles or possibly more often. You cannot over grease a greaseable u-joint.
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Do I have to measure to order a driveshaft?
YES! We want your order to fit correctly. Measuring is the only way we can be sure your driveshaft will fit and perform perfectly for you. We have provided the best measuring diagrams in the business so that you can easily get the right dimensions
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Can I send in my driveshaft so you can use it for a template?
Are you interested in learning more about Companion Shaft? Contact us today to secure an expert consultation!
Yes you can. As long as you are 100 percent sure it fits correctly. Please let us know if you want it returned.
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How much of a mistake am I allowed in my measurements?
NONE!!! Its too easy to get it right so why do it wrong. Never use the hook on the end of a tape measure to measure a u-joint. It is best done with a good steel machinists ruler or a dial caliper but if those tools are not available any good ruler will do as long as it reads down to 1/16 of an inch. Use the tape measure hook for the overall length only!
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I want to order a driveshaft but my car is all apart?
Unfortunately it will be best for you to wait until you have it back together to measure correctly.
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Is it called a Double Cardigan or is it a Double Cardan?
The correct pronunciation for the two u-joint CV knuckle on a driveshaft is "Double CARDAN" pronounced (car-dan). It is commonly mispronounced Double Cardigan. A Cardigan is a piece of clothing.....it is a sweater.
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Is it called a Spleen or a Spline?
The correct pronunciation is Spline...with a "long" I. The spleen, with a "long" E is an organ in your body.
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Is it Dana Splicer or Dana Spicer?
The correct pronunciation is Dana SPICER. Think of the word SPICE with an "R" on the end.
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How do you say the company name "NEAPCO"?
The correct pronunciation of the company name NEAPCO is "KNEE - APP - CO".
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What forms of payment do you accept?
We accept MasterCard, Visa and Discover credit cards.
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How do I go about returning a part?
To return a part please click on this link to read our Return Policy and to PRINT out the RETURN FORM. A properly filled out RETURN FORM is required to be in the box with the returned part(s) to get a refund.
CLICK HERE for RETURNS
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What is the difference between , and Series?
The "series" of a driveshaft or universal joint is determined by the actual dimensions of the u-joint. While the front and rear u-joint can be of two different sizes the shaft is only as strong as the smaller one. The series u-joint measures approximately 3 1/4 inches wide. The and both measure approximately 3 5/8 wide. The and series can have cap diameters of 1 1/16 and/or 1 1/8 inch or a combination of both sizes. The series has a cap diameter of 1 3/16 inch and the body and journals are bigger than the or . Remember is almost never found in production car driveshafts.
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When is it necessary to upgrade to series?
It is always a good choice to upgrade to the series components whenever your application is used for racing or with high horsepower and street use. Stock driveshafts were designed to handle a modest amount of horsepower. If your application has more than 400 horsepower then its time to consider a new shaft.
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What is the difference between the Chrysler and series?
The and series are the two sizes that are commonly found on Chrysler products. They represent the two stock sizes that have been used for many years. The series is the “small” Chrysler u-joint size (2 1/8 inch between flats on yoke with 1.078 inch bearing cap diameter) and the series is the “big” Chrysler u-joint size (2 5/8 inch between flats on yoke with 1.125 inch bearing cap diameter). The series is similar in size to the series and the is similar in size to the series. They both utilize the inside “C” clip design to hold the u-joint within the yoke flats whereas the and use the outside snap ring design.
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What is General Motors 3R Series?
General Motors typical u-joint size found on most passenger cars and light trucks is commonly know by a few names. They may be referred to as “3R” or “Saginaw” but they are all one in the same. Depending on who is doing the talking you may hear any one of these terms. The 3R series measures 2 9/16 inches between flats on yoke with a 1.125 bearing cap diameter. The factory original u-joints are held into the yokes by injected plastic. This u-joint is similar in size to the series. The replacement u-joints utilize the inside “C” clip design to hold the u-joint between flats within the yoke whereas the series uses the outside snap ring design. You should be extremely careful not to heat the plastic with a torch to remove the original u-joints because the heated plastic will emit toxic fumes that are not good for your health.
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My slip yoke has a space where it appears that one spline is missing.
Yes you may find that your slip yoke has the space where one spline is missing. When counting splines you always count the actual spline tooth and you will always add one more to your total count when you see the space. For example on a GM TH-350 slip yoke you may see 26 internal splines and a space...this is in fact a 27 spline slip yoke. This applies to ALL splined parts that have the space. For Chrysler owners you may see some companies list their 904 slip yoke as a 25 spline or 25/26 when in fact it has a 26 spline output shaft on the transmission. The 727 slip yoke may be listed as a 29 spline or 29/30 when in fact it is has a 30 spline output shaft on the transmission. This can be very confusing when selecting a slip yoke. The space is found on the slip yoke but is not found on the output shaft of the transmission or transfer case. There is no need to try to match the space with a corresponding spline on the output shaft. You can install the slip yoke in any position on any spline and it will perform the same way each and every time. The transmission output shaft is always the best choice when counting splines because they always have the full amount. Remember this and you will never be confused again.
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Why do I continue to break u-joints?
The answer can be that the u-joint series is too small for the application. Or possibly you are using an inexpensive parts store u-joint that does not offer strength. Maybe you are using a greaseable u-joint and it is breaking across the grease fitting hole. The corresponding yoke is damaged or distorted and causing premature failure.
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My transmission slip yoke feels like it is binding inside my transmission?
The problem may be that the internal splines of the slip yoke barrel have a slight twist and the slip yoke needs to be replaced. This problem may be the result of too much horsepower for the slip yoke design and or material. A manual transmission or an automatic with a trans brake can cause this damage because of the forces applied to the splines during a starting line launch. If you look inside the slip yoke you will see a slight twist to the spline. This twist is usually at a point that corresponds with the end of the transmission output shaft. As you insert the slip yoke into the transmission it will bind when it reaches the twisted area. Click to see photo.
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Does having urethane or solid mounts cause more driveline noise to be felt and heard while driving or racing?
YES! Having urethane or solid mounts of any kind at any location on the vehicle will transmit noise, Urethane or solid mounts can be benificial to tighten up a suspension for better performance but the down side is the noise when driven on the street.... especially in an otherwise quiet vehicle. Urethane or solid engine mounts, transmission mounts, body mounts or control arm bushings will transmit more mechanical noise and road noise throughout the chassis and interior of the vehicle. You will hear and feel these noises much more than if you had rubber mounts. Nothing dampens noises better than rubber. Depending on where the noise is coming from it can be described as a buzzing sound or a droning sound with a rythmic oscillation. You will hear every moving part in your entire vehicle including road noise. Some people are ok with this and some people will go crazy because it is not always pleasant. For racing it's ideal...for street it's annoying. If you ever had a vehicle that had an exhaust pipe or clamp come in contact with the floor or frame then you know how much noise can be transmitted. Now think of this mulitiplied by many times. Typically the driveshaft is usually not the cause, unless it is out of balance, but even a perfectly balanced driveshaft can act as the "speaker" which can amplify and transmit the mechanical noise or road noise.
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As early as the s hot rodders were looking at the engine’s camshaft as a way to increase performance. From these hot rodders famous performance camshaft brands rose up to meet the demand with names like Iskenderian, Crower, Smith, Crane, Engle, Herbert, and Winfield, among others. Rodders and racers alike found that replacing their factory camshaft with a performance hot rod camshaft from one of these companies allowed them to increase horsepower and torque along with throttle response or move the power band up or down the rpm range for their application. While somewhat secondary, upgrading the camshaft also altered the exhaust note coming from those early V8s due to the camshaft’s opening and closing timing events being altered along with the common change in duration as well.
What is a camshaft and what does it do? Put simply, the basic purpose of the camshaft is to open and close the valves that control airflow into and out of the combustion chamber. When, how much, and for how long is determined by the profile of the cam lobes. While an internal engine component, it is also generally not considered too involved to replace and the swap can usually be accomplished with the engine in the car, unlike major internal changes like upgrading the pistons, rods, or crankshaft. The camshaft can completely change the engine’s performance profile, efficiency, and exhaust note, making it one of the most popular internal upgrades amongst performance enthusiasts and racers. So, whether you’re considering replacing your camshaft due to mechanical wear limits or other internal engine repairs/upgrades, or you’re just looking to add some performance and a sweet exhaust note to your ride, it is worth replacing your camshaft.
Note that in most cases you cannot simply replace just the camshaft (some instances like roller cams you can often reuse the lifters for example). So, consider that when replacing your camshaft that you will have to budget for additional wear items to be replaced, such as valve springs, timing chain and gears, and even the cam bearings. Upgrading to a high performance camshaft may also require modification to upgrade the valve train as well. What is a valve train? That includes things like rocker arms, pushrods, and valve springs that work in conjunction with the cam to control the valves. Additionally, service parts like timing cover gasket, fresh oil and filter, valve cover gaskets, intake gasket, and more will be required as well. Lastly, many suggest tuning upgrades, such as a larger carburetor (or re-jetting what you have), and exhaust headers and/or larger diameter exhaust tubing to take advantage of your new performance camshaft’s entire potential.
Camshaft Upgrade Pros and Cons
When upgrading your camshaft, you must consider the disadvantages of such an upgrade along with the benefits. Meaning, installing a performance camshaft with higher lift and longer duration can and will affect wear on other parts of the valvetrain. For example, changing from a .410 lift cam to a .580 lift cam will put more stress (wear) on your valve springs. Increased power comes with increased wear, there’s no other way to describe the fact. There is always a tradeoff and no free lunch, so you must consider both sides of the coin here and if the camshaft you are considering for your upgrade is worth the additional wear and shorter lifespan of other engine components. This is why racing engines are regularly inspected and high wear items like lifters, valve springs, and other pieces are replaced each racing season (and in some cases after each race!).
Knowing how to properly select a camshaft for your engine takes some real world decisions as to what your plans are with your project. Are you building a high rpm naturally aspirated race car? Or perhaps you’re building a nice low rpm cruiser that needs torque to get off the line and has a noticeable chop to the idle to turn heads? Those are two vastly different camshaft profiles. Sometimes choosing the best camshaft is to sacrifice one value for another. Having that deep, lopey idle thanks to a low lobe separation angle (LSA) means having lower engine vacuum for accessories like power brakes. Weighing these tradeoffs is something that must be done to ensure you have a camshaft with the right specs for your needs. Consider rpm range, cam specs, lifter type, and overall lobe profile will aid you in your decision for the cam that is right for you.
RPM Range
As noted above, knowing your intended rpm range for your application is critical for correct camshaft selection. Matching your camshaft to the rpm usage, performance needs, and driving style will ensure your camshaft provides the optimum performance at the right rpm. If you’re looking for low-end torque for street use a camshaft with less duration would be warranted (we’ll talk about duration more below). Conversely, if you're building a high-performance or racing engine that operates at higher RPMs, you'll need a camshaft designed to deliver power in that range via more duration (among other cam specs). Consider the whole inlet tract when evaluating rpm range. If you’re running small runner iron heads with a dual plane intake that runs out of breath at 5,500 rpm, installing a camshaft with an rpm range that tops out at 7,000 rpm isn’t going to change the fact the intake and heads will restrict airflow and you’ll not see peak power over 5,500 rpm. This is why you’ll often see additional hardware upgrades with certain cam swaps, and why the “heads, cam, and intake” swap (HCI) is so popular to obtain a matched package for optimum power output. Also, remember that generally a bigger cam benefits from a torque converter with a higher stall speed in cars equipped with automatics transmissions.
Camshaft Specifications
Unless you’re going to have a custom camshaft ground to a specific set of values or camshaft recommendation from an engine builder, you don’t need to get too deep into the numbers that make up lift, duration, and lobe separation angle (LSA) camshaft specifications. However, understanding cam specs in general and what they do to the engine’s overall performance will help you compare camshafts from various manufacturers or even between camshaft series from the same manufacturer. Knowing what these values are, and what they’ll do for performance when moved “up or down” will be a huge help in understanding what a specific cam grind will do for your application. Below are various aspects of the camshaft explained to help you know how to choose a camshaft that will work best for your car.
Starting with lift, this refers to how far the intake or exhaust valve is lifted off the valve seat in the cylinder head. This can be a single number (meaning both valves move the same distance) or it can be a split value, where one valve moves further than the other. The more lift the more airflow potential, however you do need to be cognizant of piston to valve clearance with extremely high lift cams. Don’t forget too that the rocker arm ratio adds to the overall lift value as well.
Duration is a value, in degrees, of how long the valves are open. The duration can be expressed as advertised duration and/or duration at .050” cam lift. Most will compare the duration at .050” cam lift, which is measured at .050” of lift off the base circle of the cam, since it is an industry wide standard of measurement. Short duration provides more torque at lower rpm, while longer duration improves top-end performance at the sacrifice of low-end torque.
Lobe separation angle (LSA) refers to the timing relationship between the intake and exhaust lobes at maximum lift. The timing, in degrees, between the two cam lobes at maximum lift is the LSA. A camshaft with a “tight” LSA of 110 degrees or less has more overlap (the time both valves are open at the same time) and affects engine idle quality, throttle response, and overall performance. As stated above, these tight LSA cams sound great with a nice choppy idle, but vacuum will suffer. A cam with an LSA of 112 to 114 degrees is considered a “wide” LSA and will have a smoother idle with increased vacuum while improving overall drivability. As you can see, the difference between a narrow and wide LSA is but a few degrees.
Lifter Types
Determining what lifter is best suited for your application may be limited by your engine block to some extent (a vintage block cannot use OEM-style hydraulic roller lifters but may be able to use a retrofit-style roller lifter). The type of lifter used will also dictate the camshaft, as the camshaft’s lobes are ground to run on a specific lifter type (flat tappet or roller tappet). For example, can you use roller lifters on a flat tappet cam? The answer is no, since the lobes are not designed to work with a roller lifter. It is often suggested that it is best to buy your cam in a camshaft and lifter kit, but you will find some kits that also include a timing chain kit and even pushrods for popular applications.
The four types of lifters are flat tappet hydraulic, flat tappet solid, roller tappet hydraulic, and roller tappet solid. Hydraulic tappets use oil pressure to provide valve lash, whereas the solid tappet design only uses the oil pressure for lubrication and valve lash is set manually with an adjustable valvetrain. Hydraulic tappets are low maintenance and can accommodate for valvetrain wear and are also quieter. Solid tappets require periodic adjustments to maintain correct valve lash and can be noisy (especially flat tappet versions). Additionally, flat tappet lifters are known to be more precise since they do not have the oil pressure inside the lifter controlling valve lash. Hydraulic lifters can be limited by rpm range needs, as excessive rpm can cause the lifters to pump up, holding valves open. The real performance difference between flat tappet and roller cam and lifters, both solid and hydraulic, is that rollers provide extra durability with low wear and can allow more aggressive camshaft profiles to retain a high amount of street manners, providing the best of both worlds. However, roller cams are more expensive than flat tappets. Is a roller cam worth it? Read on to learn more about selecting the right cam and lifter design for your engine.
Lobe Profiles
The camshaft’s lobe profile determines the opening and closing events of the valves (both amount of lift and duration the valve is open). An aggressive cam profile provides a higher lobe lift and longer duration, which provide for increased horsepower and torque, but may require additional supporting components to reap those performance numbers (refer back to those iron heads and 5,500 rpm dual plane intake we mentioned earlier). Something a bit milder when it comes to lobe profile may be better suited for your application if you’re simply looking to replace a worn cam and lifter setup and retain your current cylinder heads, intake, and exhaust manifolds. These milder lobe profiles not only are a more cost effective way to go on the street, since you’re not replacing a bunch of supporting parts, but will provide better low-end torque, which is critical to street use. Understanding lobe profiles helps you choose a camshaft that balances performance, drivability, and engine characteristics according to your needs.
Understanding camshaft terminology and what all those camshaft numbers mean is important to determining the best cam for your application needs. If you don’t understand the difference between lift and duration and what the values do to a camshaft’s performance potential, you are essentially throwing darts at the wall blindfolded. For example, higher lift and longer duration camshafts generally offer better top-end horsepower but may sacrifice low-end torque, while narrower LSA values promote higher performance but can affect idle quality and low-speed drivability. Here’s a high level overview of what these terms mean, how cam lift vs duration vs. LSA affect overall performance, and why they matter when spec’ing a camshaft for your build.
Lift
Lift, which is measured in thousandths of an inch (.540” lift for example), is the measurement of how far the camshaft moves the lifter, and ultimately the intake and exhaust valve. As for how to measure camshaft lift, total lift is calculated by multiplying the rocker ratio by the camshaft’s lobe lift. Lift can be a single number (both intake and exhaust cam lobes have the same lift) or a pair of numbers (intake and exhaust cam lobes have different lift). The higher the lift the more air and fuel can enter the combustion chamber, increasing the potential for more horsepower and torque. Higher lift cams usually work well for high rpm use where the engine can take advantage of the additional air and fuel flow. High lift cams should always have their piston-to-valve clearances confirmed during installation to prevent valvetrain and/or piston damage.
Duration
Duration, which is measured in degrees of crankshaft rotation (220 degrees for example), refers to the amount of crankshaft rotation that the intake and exhaust valves are open. Like lift, duration can be singular or two values, one for intake duration and one for exhaust duration. Split duration camshafts often favor more duration on the intake side than exhaust to aid in packing the combustion chamber with air and fuel. Longer duration will help make more power at the top of the tach, but low-end torque production will suffer. Conversely, shorter duration camshafts produce more low-end torque and have better throttle response at the sacrifice of high rpm performance.
Lobe Separation Angle (LSA)
Lobe separation angle, or LSA, which is measured in degrees of rotation of the camshaft between the maximum lift measurements of the intake and exhaust cam lobes (110 degrees for example), determines the timing between the opening and closing of the intake and exhaust valves. This affects engine idle quality, engine vacuum levels, throttle response, and overall performance. A narrow LSA is one that is considered 110 degrees or less result in more overlap between the intake and exhaust valve opening and closing events, promoting higher engine performance but potentially compromising idle quality and low-speed drivability. A wide LSA is over 110 degrees and reduces overlap of the intake and exhaust valve events. This improves idle quality and low-speed drivability but may sacrifice peak horsepower. Higher flowing heads will often benefit from a wider LSA, as will any type of fuel injection system.
Camshaft Lift Explained
As we noted above, camshaft lift refers to how far the lifter is moved in its bore, and ultimately the valve once rocker arm ratio is figured in. The more lift, the more air and fuel can enter the combustion chamber. Lift impacts your engine’s power band and where the peak torque and horsepower happen on the tach. Higher lift camshafts offer more airflow, ideal for racing. Moderate lift balances torque and power for street driving. A lower lift prioritizes low-end torque for daily driving. To put it in a bit more detail:
High Lift Camshafts: Allow the most air and fuel into the combustion chamber, creating maximum horsepower and torque at higher rpm. These camshafts are ideal for race applications where top-end power is critical.
Moderate Lift Camshafts: These strike a balance between low-end torque and high-end power. They provide good overall performance and are well-suited for street-driven vehicles that require a broad powerband and drivability.
Low Lift Camshafts: These prioritize low-end torque and drivability at the expense of high-rpm power. They offer smooth idle, good low-speed response, and fuel efficiency, making them suitable for daily driving and street applications.
When considering lift values for your camshaft, keep in mind that the higher the lift the more rpm will be needed for peak horsepower and torque. You’ll also need to consider piston-to-valve clearance with high lift cams. Most OE pistons and valvetrain are good for up to .550 lift cams, but when in doubt, check piston-to-valve clearance or refer to your engine builder or piston manufacturer. Street applications will do well with anywhere from .400” to .550” of lift whereas racing applications often will run .550” plus lift cams and up to .800” of lift in racing applications.
Camshaft Duration Explained
The duration of a camshaft refers to how long the intake and exhaust valves stay open. This is expressed in degrees of crankshaft rotation, as explained previously. Duration affects the engine’s breathing ability, so to speak, in that the longer the valve is held open the more air that can move in or out of the combustion chamber. Increasing duration provides more airflow, creating higher peak output and improved performance at high rpm. However, increased duration sacrifices idle quality and low-end torque production for that higher rpm performance. On the other hand, reducing camshaft duration produces more low-end torque with a smoother idle quality and even better fuel efficiency, but you will have lower peak horsepower and torque.
Determining what is a good camshaft duration for your application will depend on your intended use. For street driven vehicles you will usually be looking for a shorter duration camshaft. This results in better low-end torque and drivability, which are crucial for daily driving and stop-and-go traffic. You’ll want to use durations ranging from about 200 to 230 degrees at 0.050" lift for these applications. A duration in this range provides a balance between performance and efficiency that is going to be of more value in typical street driving and the rpms that are seen on the street.
When it comes to racing applications, duration is going to be higher, ranging from 240 to 280 degrees at 0.050" lift or even higher. These longer durations maximize airflow potential over everything else. Idle quality, low-end torque production, and fuel efficiency will all suffer, but are often of little concern in a high rpm racing environment where the engine is rarely at idle or even part throttle, but the pedal is to the floor lap after lap with the engine at the top of the tach, so that’s where the peak power needs to be made.
Camshaft Lobe Separation Angle (LSA) Explained
As previously noted, camshaft lobe separation angle, or LSA, is the measurement in degrees between the camshaft’s intake lobe and exhaust lobe peak lift values. This measurement affects what is called overlap, or when both the intake and exhaust valves are open. A tight or narrow LSA (small angle value) increases overlap, while a wider LSA (larger angle value) decreases overlap. A narrow LSA is generally accepted as an LSA of 110 degrees or less, while above 110 degrees is considered a wide LSA value.
Narrow LSAs provide more overlap, and this overlap can help fill the combustion chamber, as the exiting exhaust gasses will help pull in the intake’s air/fuel charge. This is beneficial to high-rpm performance and mid-range torque production. However, there is no free ride with narrow LSAs, as a narrow LSA will bring a noticeably rough idle and low-speed drivability issues (bucking, etc.) along with lower available engine vacuum. Racing applications where sustained high rpm use is common will benefit more from narrow LSAs.
So far, we’ve discussed various camshaft attributes like LSA, lift, and duration, but your main decision will be the type of camshaft you wish to run before you even start factoring what cam specs are best for you. Since we’re mainly discussing American V8 engines here and not modern or import overhead cam applications there are four different types of camshafts that we’ll discuss: hydraulic flat tappet, hydraulic roller, solid flat tappet, and solid roller. What is a flat tappet cam? Simply, this camshaft design has a flat lifter face that rides on the cam lobe. What is a roller cam? On a roller camshaft design, the lifer has a roller on needle bearings that rides on the cam lobe. To narrow this down further you’re looking at either a hydraulic camshaft or a solid camshaft, meaning one that uses hydraulic lifters or solid lifters to actuate the valves via the engine’s pushrods. Note that on many engines that could have either came type, knowing how to tell if you have a flat tappet cam or a roller cam can be difficult. Generally, you will need to pull the intake to see inside the lifter valley. Below we will provide a brief description of each camshaft type and then compare flat tappet vs roller tappet cams and solid vs hydraulic lifters.
-What is a 4/7 Swap Camshaft: You might have heard of a cam that actually changes the firing order of the engine. Swapping cylinders 4 and 7 is a popular version of this, particularly on small and big block Chevy engines. Cylinders 4 and 7 are “companion cylinders,” meaning they are both at TDC at the same time, one on compression, the other on exhaust. Because of this, the compression and exhaust events can be switched. Why do this? Think of a Chevy engine (and many others) with a 1-8-4-3-6-5-7-2 firing order. Cylinders 5 and 7 are right next to each other at the left rear corner of the engine and they fire consecutively. Among other things, the idea of a 4/7 swap is to move the adjacent firing cylinders to the front of the engine where they will theoretically build less heat because they’re out in front and right next to the water pump. 4/7 swaps can make more power by changing how air and fuel are being pulled through the intake manifold and can have an effect on the torsional dynamics of the crankshaft.
-What is a ¾ Camshaft: The old “3/4” cam goes back to the early days of hot rodding and, unlike the 4/7 cam we discussed above, ¾ cams have nothing to do with firing order. Instead, it’s an abbreviation for “3/4 race.” In the early days of hot rodding, cam grinders typically offered just a few cams for each engine. In addition to other clever camshaft names, “3/4 race” was used to designate a cam that had lift and duration figures somewhere between “stock/mild performance” and “full race.” The modern version of this that we often see in LS cam kits is the “stage 1” camshaft, “stage 2,” “stage 3,” etc. denomination. It doesn’t really tell us much about the specifics of the cam, just establishes a rough hierarchy of where it sits on the ladder of theoretical performance.
Obviously, there’s a lot to consider when it’s time to select the right cam and the best camshaft brand for your engine. Below is a cam selection chart to simplify some of the information that we’ve discussed here. Use this cam guide as a camshaft selector tool to help you compare and contrast different camshaft designs to help you make the right decision.
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