LS1 vs LS2?

[slims00ls1z28]

Not the way you would think. What is the difference other than the obvious sensor location and bore size? I ask because I bought a Magic stick 3 cam kit several years back and put it in my Z28. Had unknown (at the time) piston to valve clearance, bent a valve, which later broke, toasting an LS1. Fast foreward. Bought my 05 GTO, put that same camshaft (with same valve springs and pushrods) that survived the LS1 into that LS2 and drove it for a year with no problems and no valve contact. Decided to put the GTO back to stock and removed the cam and rebuilt the motor (had other issues with it) and there were no marks on the pistons. Now I recently bought another LS1 to go back into my Z28. On a hunch since the motor is out and apart I decided to test clearance before I built it and put it back in the car, there is contact with the pistons. WTF? 2 LS1's had contact issues and the LS2 did not using all the same parts (cam, valve springs, retainers, pushrods). Not just the same as in bought another set I mean took all the parts from one and put them on another same, cam was installed dot to dot on all engines, no chance of having it off. Magic stick 3 cam on a 114 LSA (112+2) I don't remember the lift specs but they were higher than what's advertised on the site (IIRC my specs were in the .642/.612 lift wise as I remember it being larger than advertised). I'm going to have the pistons flycut to accept the camshaft I'm just wondering why it hit on 2 LS1's but not an LS2.

[SMWS6TA]

I believe shorter push rods would fix this, something about the height of the cylinder heads for the LS1 vs LS2. Also the position of the internals, like the cam & lifters in a LS1 vs LS2.

To long and you have PTV issues, to short and you have valve's not opening long enough or not at all.

I remember a while ago when I was looking at cams that this was one of the things besides springs that you had to check on or get to have MS3/4 work with stock LS1 pistons.


Did you get the cam from TS&P? you should call and talk with them.

[slims00ls1z28]

Yep, I talked with John, I think it was, and he couldn't explain it or offer any more help. He said something was wrong for there to be contact like off a tooth or something. I wasn't off on the last 2 and I know I'm not off this time either, especially when it's still sitting on a motor stand in front of me. All bearings are new pistons etc are cleaned etc. I asked about the shorter pushrods and he said it would only relieve pressure on the lifter not reduce the lift, I dunno. Is there a height difference in the LS1 vs LS2 heads? I was not aware of any but could make sense. Still trying to figure out what to do next. If pushrods would work I'd do it in a heartbeat just going to make sure all is right and hopefully keep the cam since the car is already tuned for it.

[SMWS6TA]

They sell a push rod adjustable to get the correct length. Goes for under $20. I'd start there first since it's the cheapest route.

[SMWS6TA]

Talk with LeadFarmer


He just installed a MS3

[04yellowjacket]

i no a guy in okc ok that has a 611 lift cam in his stock ls2. runs fine. not for sure what kind it is either.

[redbird555]

i no a guy in okc ok that has a 611 lift cam in his stock ls2. runs fine. not for sure what kind it is either.

Lift alone has little to do with ptv... Duration and lift determine what is safe and whats not. To the op the ls2 uses 243 heads wheres the ls1 has 241s, the 243 use a smaller chamber to raise the compression but perhaps they have a slightly taller deck height, not really an easy way to tell. But the rule is to ALWAYS measure and never guess, that way the PR's are sized correctly for the motor, and you ensure no ptv clearance issues.

[SMWS6TA]

A for sure way to check is by using clay. It means more work due to installing the head and removing it, but you'll know for sure.

Use about a 1/4", press onto the piston (if you have valve relief's place there), spray a little WD40 (to insure the clay doesn't stick to the valve) on the clay, turn the crank over 2 full cycles.

Next take a razor and cut the clay straight down, now you have an accurate form of how close the valve comes to contact the piston.

[slims00ls1z28]

Yep did that. In my case it was cut where they made contact and left small indentations in the piston. Stopped the build cold for now. Logic would point towards getting a smaller cam if for sure that is the problem. TSP keeps saying it shouldn't be contacting that something is wrong but that's just not the case. I don't have the cam card anymore but I'm betting more like the specs are off one way or another. I know for a fact the lift specs were higher than even the MS4 on the exhaust because I remember that specifically but maybe there's more to it. For now though and probably like the first engine this cam toasted there's contact. I'm actually looking at other options I wanted to do anyway later, Stroker kit with pistons with valve reliefs. My local machine shop says the pistons are a little thin to flycut and be safe especially since I'm planning to spray it so might as well wait the 3 more months (income tax is mine this year) and go all out yet do it right. Everything else is built to handle way more than I have so might as well suck it up and do it right.