I tried searching but it gives me a server busy message so I figured I'd just ask you pros in the forum.

What is the max lift for a stock LS1 head? I have a FMS F10-12 with 228/228 - .575/.575 and wanted to go with Harland Sharp 1.8 roller rockers. I've upgraded the valvetrain when I did the cam install but with these rockers it will bring the lift to .609. Will I have enough piston to valve clearance and will the rockers clear the valve covers or do I need to get spacers?

Thanks for the help in advance!

 

Clay it. Also depends on how you time the cam obviously.

 

Do you want to know how far you can open the valve? It has to do with a lot of things, the first being coil bind of the springs, if you try and exceed that it will cause a big mess.

Bret

 

Lets say I was going to put in a cam in a stock LS1, what would be the max lift cam that would fit without changing the heads (i.e .600, .610 ect . . .) My springs are good for .625 so bind shouldn't be an issue. I'm still pretty new at this stuff in American muscle so excuse the ignorance. I just want to make sure I can install the roller rockers and not destroy anything. The rockers will increase lift to .609 on both sides.

 

If you install the cam strait up I don't see you having any problems. There are cams with .040 more valve lift out there for stock motors.

 

You should also check with the FMS. Some of the cam manufacturers out there do not recommend running higher ratio rockers due to the aggressive ramp rates of certain camshafts. In theory you would be good with that amount of lift though. There are quite a few running the T-rex and Magic Stick cams with stock heads/pistons. Some have higher lifts, but they've flycut their pistons for them. I really think the best bet would be to talk to FMS first.

 

Lots more than lift determine if the cam will "fit". It's all in the cams valve events and where they are in relation to the piston. X cam with .600" lift might not fit where as Y cam with .650" lift will. However, with the cam you have, i don't think P/V will be of concern with the .609" lift. I highly doubt lift will play any concern in wether or not the rockers will fit under the covers either. As with all cases, it's best to throw a piece of clay on top of the piston and roll it over. You can never be to safe.

 

Thanks for the info guys. Now I know what "clay it" means as well!

 

I have a MS4 and the cam card reads 651 Intake & 609 Exhaust. I have not had any problems with mine.

 

Is anyone running 1.8s on a big cam like a ms3 , 4 or trex ?

 

great question

 

Thats actually a ridiculous question because it wouldn't be necessary.

 

lmao. well, then explain it since you know so much

 

its not about advertised lift, or lift with your rocker arms.. its about the cam specs, if the valve is heald open for a really long time its going to hit, even if it has stock lift specs. with a 228 i personaly dont think youd have an issue, but then again im not a cam god. im just going by the fact that a 242 duration cam with more than .600 lift dosent need flycutting

 

some larger bodied aftermarket rocker arms require grinding on the valve cover or using a spacer regardless of the lift.

 

thats not really going to be an issue if you have -2 vavle reliefs. from what i undersand. teh comp guys and performace guys worry more about valve float because of the high ramp rates. saying that. i seen big block chevy valve spring on a 750 lift and they uses 1.8 shaft mounted rockers.

 

Thunder Racing says:

"Due to the fast ramp rate of this camshaft, the use of 1.8 rockers is not recommended."

I'd say anything with fast ramp rates, like XE-R lobes, stick with a stock rocker ratio.