Just swapping out a cam in my '04 LS6 engine and tought I'd share some info that I couldn't find beforehand.

Stock LS6 cam base circle= 1.495
Comp XR265HR Hi-lift base circle= 1.485

The stock LS6 pushrods with only 70k measure between 7.395 and 7.398 so far. Haven't measured them all yet. But that's alot of difference between pushrods! I don't know if it's just wear or poor machining. The latter, I bet.

So the answer to "do I need new pushrods" is definitely "YES DAMMIT"

So if I get 7.400 pushrods I'm still around .010 short. Any suggestions?

 

So does the LS6 cam have a smaller base circle than the other ls1, lq4 cams?

I'm looking at a similar cam to that comp, and I really don't want to have to change my pushrods due to a difference in base circle size.

 

I heard the 02-06 Ls6 also has longer valve stems or something, so the smaller base circle doesn't matter. Either way, just look at the recommended pushrods for your cam/engine and it will tell you what length you need. I still don't like the .010 difference between the two cams.

These stock pushrods are junk, IMO. $100 well spent on TSP or Comp hardened.

 

Push rods are a good idea for any LS engine, the stock ones are weak.

You ll be just fine with aftermarket 7.400 push rods. I went with Comps .105" wall 7.400 push rods myself even before my cam swap in my LQ9. I want the stiffest push rods I can get.

Ive swapped cams to a Comp cam and I'm still running the exact same push rods without issue. Our lifter have about .200" of plunger travel.

 

the base circle should be on the cam card.

 

What kind of preload are you shooting for? I would go for no more than .025-.050" preload.

 

What makes you shoot for that range? Stock preload is more like .100-.120" IIRC

You can gain RPM and valvetrain stability by almost botoming out your hyd lifter, thats why there are "Short travel" lifters out.

 

I've never seen a cam card with the base circle on it

 

I'll have to read up on how to measure preload. I don't get how you can measure without the lifters being pumped up.

 

The oil keeps them pumped up and helps the spring in the lifter. You measure Prod length with a length checker then add in the needed pre-looad. Amount of preload needed is determined by what lifters you are using. The less preload the more power you can wring out of the motor but obviously only to a certain point before the lifter starts bouncing off the lobes. The LS7 lifters have a much stouter spring in them and the cup position is also higher up. With those lifters you can run less preload, spin more rpm and get a bit more power out of them. If you're running stock lifters I wouldnt worry about running standard length pushrods.

As far as strength on stock rods, they work just fine on a single spring setup, V8 ran his 5.3 up to 7K for over a year on stock rods and 918s.