absolute minimum p/v clearance on intake valve
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Joined: Dec 2002
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From: Bring it........ b*tch
Are you sure the heads were unmilled when you bought them? Cause I could see if they were shaved .015 when you bought them, then you did another .030 more you could possibly have tight clearances like that..... but I have never heard of such a small cam being that tight with just .030 taken off. The cam has small lift, not much duration and on a 112 LSA, plus you have the smaller 2.02 intake valves.
Just for example, my last setup was a 232/240 .598/.605 112LSA 108ICL XER Comp cam and a set of Stage II LS6 heads shaved .015 with graphite gaskets and I still had .072 clearance. So how I had .072 clearance and you only have .056 seems a little lost on me. You were using head gaskets when you checked the clearance right?
Just for example, my last setup was a 232/240 .598/.605 112LSA 108ICL XER Comp cam and a set of Stage II LS6 heads shaved .015 with graphite gaskets and I still had .072 clearance. So how I had .072 clearance and you only have .056 seems a little lost on me. You were using head gaskets when you checked the clearance right?
Oh man! I'm suposed to use gaskets? lol Yes I had gaskets but thanks for asking. I CC'ed the chambers before I milled them and they were the stock size. I bought them used and he said that they were unmilled. I've pretty much decided to give'r hell and see what happens. I guess I will let you guys know what happens.
thanks for the input, Richard
thanks for the input, Richard
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Joined: Dec 2002
Posts: 1,084
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From: Bring it........ b*tch
Originally Posted by extreme01ta
Oh man! I'm suposed to use gaskets? lol Yes I had gaskets but thanks for asking. I CC'ed the chambers before I milled them and they were the stock size. I bought them used and he said that they were unmilled. I've pretty much decided to give'r hell and see what happens. I guess I will let you guys know what happens.
thanks for the input, Richard
thanks for the input, Richard
Extreme , I've got AS heads and am in the process of installing a CC xer 228/230 and am going to have to flycut my pistons. I'm only running .043 with unmilled heads and 2.02 valves. I've got a post going in this section on measuring p/v clearance read it. What i have found is that when Jay set these heads up he hung the intakes way out on the edge of the valve seat to maximize flow and that's the reason his 5.3's are so tight. Also to find out how much your heads have been milled, simply measure the thickness of the head bolt boss closest to the exhaust port , unmilled heads measure 1.615". Also, from the deck of the head to where the valve cover gasket rests on the head is 4.750" on unmilled heads.
Thanks for the input on measuring the head to see if it has been milled, I will check that and get back to you on it. I read your post on measuring the clearance, a little confusing for me. And my heads are already installed on motor so it wouldn't work for me anyway. You say you have .043 and need to flycut. my whole reason for milling was to bump up compression. If I fly cut I will lose what I gained and just as well not have bothered 
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Verdad Gallardo The way I understand fly cutting, is that if the intake is cut about .050 and the exhaust .025 then you only lose a little over 1 cc, so there is minimal loss of compression.
I can't get an acurate measurement on the head thickness with it installed. If I end up pulling the head can I reuse the cometic gasket? and how would I go about flycutting the piston?
I think you can reuse the Cometics but I'm not positive. I clayed my intake valve last anight and verified that I only have around .045 clearance, so I have no options I have to fly cut. My AS's are not milled.
Well I got good news and bad news. I got the engine completely installed and running here the other day with no clearance issues with my .046 intake valve clearance. at least at lower rpm, I have not drove the car yet just reved up a little bit in neutral. The bad news is that I fell victom to the, good 'ol notch in the head with the mls gasket, coolant leak. and am not very happy about it. I called cometic and asked them about it and they did not know any thing about it, they said they did not make two differant styles of head gasket for the ls1's so I should be "good to go" well they were wrong! so I get to drop the engine to r&r the heads to change the gaskets, but I guess it will be a good chance to inspect for p to v contact. Does any one know the compressed thickness of a stock gm graphite head gasket?
Compressed thickness for the graphite gaskets is .053-.054, anyone that says differently is wrong. I measured them in about 20 different places. Sorry to hear about your problems. I'm up and running, due to a screw up using the Isky tool my intakes ended up being cut .060-.070 instead of .045-.050. You really want to get Cometics, I ended up having to use OEM graphites. No one had .045 Cometics so my quench is off.
I believe they are 853's. Yeh I thought I wanted cometics too but not after this. I will also measure the head thickness while they are off so I know for sure what I've got as far as how much they have been milled. Thanks for the input on the thickness of the stock gaskets.