We just finished up a cam swap on a friends 05 silvarado 5.3L, we cranked it up and the thing sounds like a diesel. We re-torqued all the rocker arms and checked everything we could find without pulling the entire car back apart. It almost sounds like there is some PtV clearance issues, but the timing was checked 3 times and we felt no interference when turning the motor over by hand. Does anyone have any ideas? This is driving us crazy.

Setup:
Futral F-2 cam (224"/224" .588"/.588" 114LSA)
PRC dual spring kit
TSP 7.400" PRs
Cold air intake

The rest of the truck is bone stock.

Any help would be appreciated,
Kevin

 

its normal unless you have a colasped lifter. with that tiny cam you shouldnt have P/V issues

 

it should sound like a sewing mechine

 

I didn't think there would be any piston to valve issues with a cam of that size even if it was off by a tooth (although timing was checked several times). But it sounds a lot different from when I installed the FMS F14 cam in my camaro. I can't think of anything else it could be.

Thanks for the help guys, keep the ideas coming,
Kevin

 

how long did you let it idle, because when i did mine it did the same but cleared after 15 min. the lifters needed to set in

 

might have a colasped lifter

 

Could the smaller base circle of the cam require longer pushrods? (maybe 7.425?) The lifters may possibly be jumping off the lobes of the cam. I can't remember where I got my pushrod length checker, but it was less than $20...

 

the smaller base circle i thought only applied to the Z06 cam? 7.400 pushrods should be ideal for that set up.

 

The truck only has 12k miles on it, so I don't think the lifters are the problem. Its probably just the new valve springs, maybe I'm just being paranoid. The truck seems to run fine, it holds idle fine which actually suprised me considering its a bone stock auto with no tuning yet.

I'm going to try to post a sound clip soon just to make sure.

Kevin

 

I've seen a 2004 hold idle fine when first cranked and get to where it was a "2 footer" after about 15 minutes of ideling