Generation IV Internal Engine - 6.0L piston questions (LS3 heads W/ comp 54-469-11)

I called summit and they sold me a set of .30 over flat top pistons with no valve reliefs. Is anyone else running a 6.0L iron block with comps LSR cam 54-469-11 with the LS3 heads? I am worried about PTV. I want a set of pistons that are flat top with valve reliefs. Can anyone help me find a set of pistons that are 4.030 with valve reliefs? I dont want to risk the motor or mock it up with these pistons and find out they will not work and not be able to return them.

Why dont you call summit again and swap them for some with valve reliefs?
cheers Russ

K398x3 wiseco's.


That's what I have. Will run you about 700 bucks but they come with rings, pins and circlips.

You will need a rod with a .927 pin bore tho.

Diamond also makes great pistons. Wherever you end up going to get your pistons, make sure they have L92/LS3 valve reliefs. THey are a little bigger to accomodate the larger intake valve of the L92/LS3 heads.

Most aftermarket pistons require a 6.125" rod as well.

Hot Rod did an article a while back and I think the 227@ .050 LSr cam was the biggest they could fit without valve reliefs so yours most likely requires reilefs, but you ALWAYS have to measure for yourself.

EDIT: I found the article; http://www.hotrod.com/techarticles/engine/hrdp_0909_gm_ls_engine_cam_test/viewall.html

Thanks SWEETS10V8! That article was extremely helpful. Printed it out and read through it a couple times already. I think I am going to keep my pistons and send the 54-469-11 cam back.

I now am planning on running comps 54-456-11 cam and returning the 54-469-11.


specs on new cam are: 219/227 .607/.614 112

I found my old post where I said what my PTV was, I thought it was tighter than this. But that must have been about the 223 cam I tried before the 219.

SWEET! I got my cam and I have enough piston to valve clearance. I was a little scared I might not have enough because I had at least four things working against me.

1. Heads are milled .030"

2. Intake valve is huge, 2.160"

3. Piston is a true flat top with no valve relief

4. Piston sticks out of the hole .007-.008"

I ended up with .090" intake, .085" exhaust, I can live with that! I should start buttoning up the engine this weekend!

I found my old post where I said what my PTV was, I thought it was tighter than this. But that must have been about the 223 cam I tried before the 219.

those ptv clearance numbers are for the 219 cam correct? thanx, rob :usa:

i know tsp has a 231 cam and it doesnt hit but who knows what intake centerline they grind it on. I have a 229 236 cam from tsp that doesnt hit but both of these shouldnt on unmilled heads. I am planning on going fi so i will be selling it on here.