Need Help with Piston to Valve Clearance problem
Need Help with Piston to Valve Clearance problem Installed my new cam last night after waiting for it for over 2 weeks (another story). Got it degreed in and checked piston to valve clearance. Here's what I came up with using the valve drop method:
intake - .041", exhaust - .088"
installed at a 110 icl
The intake valve is tightest at about 8* ATDC
Here are the cam spec's: COMP XE-R 232/232 .595"/.595" 111 lsa 109 icl
This is with unmilled heads with 2.02 / 1.575 valves and .060" GM MLS head gaskets.
I asked 4 different knowledgeable places if it would fit and all said it should, no problem.
My questions are 1) if the valve drop method is conservative, because this it way too tight. 2) I used my 7.400 pushrod and just tightened the stock rocker arm down until I got 0 lash. Could this throw off the rocker geometry enough to give me inaccurate readings? If the answers are both no, then it looks like I'm sending this one back.
Craig
intake - .041", exhaust - .088"
installed at a 110 icl
The intake valve is tightest at about 8* ATDC
Here are the cam spec's: COMP XE-R 232/232 .595"/.595" 111 lsa 109 icl
This is with unmilled heads with 2.02 / 1.575 valves and .060" GM MLS head gaskets.
I asked 4 different knowledgeable places if it would fit and all said it should, no problem.
My questions are 1) if the valve drop method is conservative, because this it way too tight. 2) I used my 7.400 pushrod and just tightened the stock rocker arm down until I got 0 lash. Could this throw off the rocker geometry enough to give me inaccurate readings? If the answers are both no, then it looks like I'm sending this one back.
Craig
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From: Hartsdale, NY
----intake valve is too close if your measurement is correct....I think your supposed to have at least 75 thou clearance ...
If you have stock heads and are testing clearence with the used head gasket I think you have an issue; try another hole from the other head and see what you get....
DONT - try this motor until you have this measurement issue ironed out!
If you have stock heads and are testing clearence with the used head gasket I think you have an issue; try another hole from the other head and see what you get....
DONT - try this motor until you have this measurement issue ironed out!
After speaking to LG, TSP and FMS this morning, I'm thinking my measurement may be off due to the rocker arm geometry being off. I'm going to re-check my numbers tonite using an adjustable pushrod and see if that helps.
I know a lot of guys are running this same intake lobe so it *should* fit. Just need to get my #'s to satisfy that. It's the same intake lobe from the G5X2 and it's even on the same 110 icl.
I know a lot of guys are running this same intake lobe so it *should* fit. Just need to get my #'s to satisfy that. It's the same intake lobe from the G5X2 and it's even on the same 110 icl.
Well, I just finished re-checking my numbers with an adjustable pushrod and no dice. Got the same numbers as before.
I just don't understand it. My valve drop is .181" at TDC. There should be plenty of clearance with these heads.
Looks like this cam is coming out and I'll be calling TSP or FMS for one that fits.
I just don't understand it. My valve drop is .181" at TDC. There should be plenty of clearance with these heads.
Looks like this cam is coming out and I'll be calling TSP or FMS for one that fits.
That cam should fit with no problem at all. Ideally you want ATLEAST .080. I think your doing something wrong, but I dont know what. I have the 232 240 in my car with stock heads and i still have plenty of room. Are you sure your heads are not milled at all. If not then you must have the cam degreed in alittle advanced. Back it up to 112 and see what you get. Again this cam should fir with no problems, dont send it back yet un till you have someone as knowledgeable to check your work. Good luck
I think the reason the 232/.595" XE-R lobe fits on stock heads is beacuse the stock valves are smaller and the seats are more recessed in the head. A stock headed car usually has a piston drop of around .200" from what I've researched. Mine (and others I've seen with aftermarket heads) is in the .18x" range. There's .020"+ right there. If I had that much more, I'd call it good. To run the G5X2 cam, LG requires .200" valve drop at TDC. That cam uses the exact same intake lobe as my cam on the same ICL.
Sure, I could retard it from a 110icl to 112 icl, but I'd need to modify my cam gear by installing an offset bushing. I'm not sure that would give me an additional .020" clearance, much less what effect it would have on the powerband. Besides, the exhaust was getting tight at .090" and retarding the cam would decrease that.
I'm 99% sure I'm doing it right. I'm following Crane's instructions to a "T" with the exception of using a solid lifter (rocker is still set at 0 lash though). What else could I be doing wrong?
Sure, I could retard it from a 110icl to 112 icl, but I'd need to modify my cam gear by installing an offset bushing. I'm not sure that would give me an additional .020" clearance, much less what effect it would have on the powerband. Besides, the exhaust was getting tight at .090" and retarding the cam would decrease that.
I'm 99% sure I'm doing it right. I'm following Crane's instructions to a "T" with the exception of using a solid lifter (rocker is still set at 0 lash though). What else could I be doing wrong?
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Originally Posted by 9secbird
That cam should fit with no problem at all. Ideally you want ATLEAST .080. I think your doing something wrong, but I dont know what. I have the 232 240 in my car with stock heads and i still have plenty of room. Are you sure your heads are not milled at all. If not then you must have the cam degreed in alittle advanced. Back it up to 112 and see what you get. Again this cam should fir with no problems, dont send it back yet un till you have someone as knowledgeable to check your work. Good luck
mike
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Verdad Gallardo Well, I didn't read the part that you were using aftermarket valves 
That makes sense to me why the #'s are off then. You could just pull the heads and fly cut the pistons. I know thats a lot of work, but it might be worth it power wise. That looks like a nice cam...just not enough duration for my application, but should perform really well.
That makes sense to me why the #'s are off then. You could just pull the heads and fly cut the pistons. I know thats a lot of work, but it might be worth it power wise. That looks like a nice cam...just not enough duration for my application, but should perform really well.
Originally Posted by dazman
i have the 236/242 comp xe-r.... do you think it will fit on stock heads???
mike
mike
