I just purchased a stage 2 BTR cam kit directly from BTR. I’ve always been into supercharged Mustangs and always left the cams alone for driveability reasons so have zero experience in cam selection or installation, let alone choosing the correct pushrod length. I told the salesman at BTR this as well and let him pick everything for me. He sent me 7.425 pushrods and some of my fellow local LS friends have raised an eyebrow at this saying they thought they should be 7.400 instead. I’d love to hear a little feedback here as I would truly assume the BTR employee probably knows what’s best but others have made me doubt that. I was reading in one of Oldmotorhead’s posts that he actually ended up going with a shorter pushrod with better results but he also has ported, milled heads with some Cadillac lifters? Could be wrong on this as it’s 3 am and I’m not fully awake yet....

Anyone who has experience with this please chime in, pushrods are cheap enough that I don’t mind buying more or sending these back for a swap out. The reason I went with a stage 2 cam was for driveability and longevity of the engine and I sure don’t want an incorrect pushrod length to sabotage that! Thank you in advance for any replies!

 

I would rely on BTR's recommendation. The cam you chose is probably one of their most popular. They should know. That cam is most likely ground on a smaller base circle. That puts the peak of the lobes and the backside of the lobes closer to the center of the cam....for lack of a better explanation. For this reason, you need a slightly longer pushrod to get the proper preload on the lifters.

 

Measure when you are assembling and will it tell you exactly what you need.

 

The full stroke length of the plunger inside the OEM LS lifter is .180"

The recommended lifter preload for the LS engines is .070" - .130"
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Yes, the base circle of the aftermarket cams are usually slightly smaller than the OEM cam, but using the stock length push rod will certainly keep you within the required lifter preload.

 

There is no way to know for sure what pushrod length you need until you have the cam installed in the car. You have to measure for the length you need.

Stock push rod length is 7.400. With most aftermarket cams, the base diameter of the cam lobes circles get reduced (versus stock) and the end result are lobes with higher lift. Because of this (keeping everything else the same as stock: deck height, head gasket, etc.), you typically need longer pushrods

Regardless, you should always measure so that you have the proper lifter pre-load for the lifters you are using.

 

Here .... Check this post from American Heritage out

https://www.corvetteforum.com/forums...iy-thread.html

 

I bought my stage 2 cam package from BTR and they recommended 7.400" push rods for mine. Stage 2 cam LS3. No head work.

 

Yup ... and a 7.400" pushrod is stock length for the LS3

 

Thank you for all the replies guys. Considering spring is literally right around the corner I may hold off until winter to start this project so I’m not rushing through the job. Maybe my best bet is to order a set of 7.400 pushrods to have as well in case that’s what I need. The car runs really strong stock but I think the cam will make it a little more fun to drive.

 

I'd give BTR another call and see if they give the same answer again.

 

They sold me 7.400 for my BTR2 cam too.

 

A full turn of the bolt to get from 0 pre load to 22ft/#'s is about .08 preload. A turn and a half gets you .120. Anywhere in there is fine.

If you want to buy an adjustable length pushrod, that's another option. Just know that the chamfer/bevel on the ends of the pushrods can vary and that can change the measurements. I have a very well equipped shop and I don't have anything that can measure either side of 7.4" with a good degree of accuracy. I use the "turn" method and it works for me....no matter how "redneck" some may think it is.

 

Yup ... somewhere between a 1 1/4 to 1 1/2 turn will get you the preload that is just fine for the LS3.

 

I installed that same cam in my brother’s Gen V Camaro along with stock LS3/7 lifters and the original stock LS3 heads from my vette, and we used 7.400” pushrods and they were perfect in terms of preload.
I would speak to BTR first and ask them why they would recommend the .025” longer pushrods. Unless they changed the base circle on their Stage 2 cam, which I doubt very much, I would go with the 7.400”.
BTW: you’re going to love that cam. Nice choppy idle, no off idle surge or lugging, easy to tune and makes good power. Great cam for a daily driver, especially with a ~ 3200 stall converter.

 

Works for me too. Everybody knows you’s a badass redneck.