Pushrod selection

[NightmareZL1]

When looking at camahaft kits on various websites, what size should be selected. If I am not removing heads and not replacing the rockers, is the 7.40 the standard size? Thank you for any help

[Stephen12ZL1]

http://www.ctsvowners.com/forum/4-en...hrod-info.html
http://www.compcams.com/Products/CC-...rods%27-0.aspx
http://www.grrrr8.net/showthread.php?t=34855

All of these links are good. It appears 7.4" is correct. Take out a stocker and measure it just to be sure or ask a guru here like ADM, Davenport, PCM of NC, etc.

[Kevlar382]

Call Lingenfelter. They can help you with any questions that you have. 260-724-2552

[DrkPhx]

If I am not removing heads and not replacing the rockers, is the 7.40 the standard size?

Most shops that sell cams will also sell and recommend the pushrod length as well. Contact them for details. Make sure they have experience with this application.

With that said, it really depends on the base circle of the new cam which are typically smaller in diameter compared to stock. Always measure to make sure. The accepted length for the LS pushrod is 7.40", but every time I have measured (with a digital micrometer) them from various applications (including the LSA) it comes to 7.385". Note: LS7 pushrods are a different length.

Here is the basic formula to use to calculate pushrod length (assuming stock heads and rockers). You can also use an adjustable pushrod checker to physically check for the correct length, but those usually require a temporary solid lifter installed to ensure an accurate reading and that means removing the heads.


Stock cam base circle diameter - New cam base circle diameter / 2 + stock pushrod length.

Example: 1.53"-1.45"=.08" then: .08"/2=.04"+7.385=7.425" << new calculated pushrod length.

These are just sample numbers and once again you always should measure first to make sure and consult the shop you buy the cam from. Hope this helps.

[Stephen12ZL1]

If you call a cam vendor like Brian Tooley, I am sure he can help you.

[jon6.0]

It also depends on what lifters you decide to run. When I ran the Morel link bar lifters in my last engine I set them at .030" preload. Some also prefer to run the stock lifters with a little less preload than what it calls for stock. I like .040"-050" preload on stock lifters. Talk to your shop and also who you are getting your cam from. Running less preload helps prevent the lifters from pumping up under higher rpm. I also recommend using a 3/8" pushrod if you have the clearance to use a thicker pushrod. Better stability. If you can't run a 3/8" then a thicker wall 5/16" is better than the standard stuff. Standard is .080" wall and you can get .110" and .135" from places like Smith Bros and Trend. Look up videos on Youtube of pushrod deflection to see how much they bend.