I know that this cam has a smaller base circle? (not to sure if thats what its called, correct me if i am wrong) but i know that longer pushrods have to be used. i have patriot gold 8401 and comp pushrods 7955-16 7.4 pushrods. will these work with this or will i need new pushrods. i will also need the ls7 lifters correct? am i missing anything else?

-Justin

 

You're correct, base circle is the diameter of the cam lobes when off the lobe ramps. LS6 cam is smaller, but I'm not sure by how much. LS7 lifters also have the spring cup sitting higher, so these two measurements could cancel each other out. I assume you're considering deleting the Active Fuel Management? If that's the case you're going to need more parts (there's a few threads here and in the GM Engine, and GMT900 sub forums).

Obviously the best way to determine PR length is to measure lifter preload...7.4 is a safe length though and may end up being what you need.

 

alright glad i was right one that...can anyone confirm this?

 

Here's what I've found out here...if you do the math, the .050 smaller base circle would warrant 7.425 pushrods, but a lot of guys have actually used the stock pushrods which are 7.38 and gotten away with it. Of course, as mentioned, best way to find out is to get a pushrod length checker and check lifter preload, there is a sticky with a lot of good info on this

So even though it's not a solid answer, guys have found that either 7.425 or even shorter stock pushrods will get the job done...I'm not aware of anyone who has run the stock pushrods checking their pre-load though, so I don't know if it's the optimal situation, I just know that guys have done it and run it.

 

well thanks for the reply. so there is hope for these 7.4 pushrods i have then. ill be sure and get them checked when i do install the cam.

 

From my research the LS6 cam and LS7 lifters about cancel each other out, but you always gotta check!

 

okay this is what im thinking as well after i have read and read both of them will cancel each other out. but i still dont know if the 7.4 will actually work. guess i wont know till i check the lifter preload. or someone chimes in.

 

You can run 7.4s, but you're pushing it for the LS7 lifter preload...they'll be preloaded over .100". Since the cups sit .060" higher and that's on a .050" smaller base circle, technically you'd need a pushrod .010" shorter than stock. I run 7.350" rods on a similar setup and it's well within preload range.

 

What kinda preload did you get with the 7.35 PRs?