jjones205

My LC9 decided to permanently drop a couple of cylinders so I decided to swap in a LY6. Ive never been into a gen IV LS motor, so this has been a learning experience to say the least. I'm stuck on the pistons, wrist pin bushings, and a timing set.

Pistons and Rings -
I originally planned on using the original pistons and just installing new rings. I noticed while cleaning one of the pistons that it had a very small piece missing from the skirt. I also cannot find rings as mine are 1.25mm, 1.5mm, and 3mm... most of the aftermarket replacement rings are 1.5mm, 1.5mm, and 3mm. I am now thinking that I will replace all of the pistons. I have found a set at Summit Racing ,slp-h1129cpa. These are flat top pistons and they do not have valve reliefs. I am looking at these specifically because they are in stock and I can get them tomorrow. I did a VVT delete and the new cam has a 265/271 lift. Do I need to look for pistons with these valve reliefs if I am running this cam? or will a straight flat top work? my original pistons are slightly dished with valve reliefs.

Wrist pin bushings -
most of the wrist pin bushings in the LY6 are worn and need to be replaced. I am having trouble sourcing these bushings as my pins are .943 full floaters. My local GM dealer told me that i would have to buy a rod assembly that comes with the bushings installed. I just cant see spending $165 for a rod assembly just to get a $5 bushing. i have the means to install and fit them. Are these bushings available and where can i get them?

Timing set -
when I did the VVT delete and changed the cam, i went back with a 3 hole cam. I bought a Comp Timing set 3172KT, but it is an adjustable timing gear set. Too many moving parts for me and i know that it will be fine once everything is tight, but i still prefer a solid gear set. Also, should i run a double roller chain since i have upgraded the cam and valve springs. I used a Comp Cam 54-454-11 with Beehive springs 269118CS. where can i source a solid gear set?

This is all going in a 07 suburban 4x4 daily driver....
Any input would be greatly appreciated!

Thanks

pannetron

With a cam with that much duration, lift and low LSA, I'd be worried about intake valve clearance with a flat top piston.

stereojnky

iTrader: (19)

Are you sure that your bottom ring isn't 2.5mm? If it is, you can use stock ls2 rings by Hastings. Part # HAS-2m5170

KCS

iTrader: (20)

I think you have the cam specs mixed up. The specs for the cam PN you listed below isn't even close. Your valve lift is .614"/.624", which doesn't really even matter for PTV clearance. The piston is way down in the bore when the valve is fully open. There are calculators online that can help you determine if you need valve reliefs or not. They're usually in the form of Excel spreadsheets that you can download.

How did you come to the conclusion that they need to be replaced?

I would have a machinist check the ID of those bushings. I usually see them with about .0005" clearance with the wrist pin, which is really tight IMO. I normally hone them a little bit to get about .001" clearance. A machine shop may charge about $5 a rod to hone them.

I'm not a big fan of the Hex-a-just stuff either. I like to use N-Motion or JP Performance timing sets. Most of the sponsors of this site will carry them in any configuration you need. A single chain is fine for most applications, and has less friction, but a double is considered safer, but you have to space out the oil pump and clearance the front cover. The double rollers take a little more work to install, but nothing too crazy.