Head Install Tonight How to Measure PV??
08-25-2005, 09:25 AM
#1
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Head Install Tonight How to Measure PV?? One of my old heads are off, the other will come off tonight, then I mount the AFR's.
Can someone tell me how to measure the PV clearance in simple terms?
The heads have been milled to 64cc's
Cometic Gasket .040
The cam is:
230 228
112 LSA
Intake Lift .592
Exhaust Lift .571
I don't anticipate any issues but Tony would never forgive me if I didnt check first
Dave
Can someone tell me how to measure the PV clearance in simple terms?
The heads have been milled to 64cc's
Cometic Gasket .040
The cam is:
230 228
112 LSA
Intake Lift .592
Exhaust Lift .571
I don't anticipate any issues but Tony would never forgive me if I didnt check first
Dave
08-25-2005, 11:24 AM
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What's your ICL? I had my heads milled .010" (64.34cc) with cometic .040", my cam is a 224/228 .581"/588" 112LSA @ +2 I had .094" Intake and .110" exhaust. P/V will depend on cam advance also.
Best way to check clearance is to use light checker springs and a dial indicator.
After the light spring is intalled on your intake and exhaust valve, install a pushrod with zero lash or use a pushrod length checker set to zero lash and find TDC on the compression stroke, and make a mark on the crank pulley that lines up with something you can gauge, I use a water pump bolt. Mount your head with intake gasket with a couple of head bolts snug, not torqued. Set your dial indicator on the intake valve as close to the center of the valve stem as possible and at the same angle as the valve. Turn the motor over until the intake valve starts to open. This will be around 3/4" of a turn more. When the mark on the pulley is within an inch or so from the gauge mark start pushing the valve down with your finger until it contacts the piston. Continue turning the motor over in 1 degree increments and while pushing the valve down with your finger you will find a spot where the valve is closest to the piston. Let your finger off the valve, set your dial indicator to 0 and press the valve with your finger again until it contacts the piston. Note the measurement on the indicator and that will be your p/v for the intake valve. Turn the motor over to TDC on the compression stroke and repeat the procedure for the exhaust valve. it will be closest as it is closeing, so you'll see it opening, then start to close, that is when you should start to measure it. The exhaust valve is closest when the piston is chasing the valve up, and the intake is closest when the valve is chasing the piston down.
Best way to check clearance is to use light checker springs and a dial indicator.
After the light spring is intalled on your intake and exhaust valve, install a pushrod with zero lash or use a pushrod length checker set to zero lash and find TDC on the compression stroke, and make a mark on the crank pulley that lines up with something you can gauge, I use a water pump bolt. Mount your head with intake gasket with a couple of head bolts snug, not torqued. Set your dial indicator on the intake valve as close to the center of the valve stem as possible and at the same angle as the valve. Turn the motor over until the intake valve starts to open. This will be around 3/4" of a turn more. When the mark on the pulley is within an inch or so from the gauge mark start pushing the valve down with your finger until it contacts the piston. Continue turning the motor over in 1 degree increments and while pushing the valve down with your finger you will find a spot where the valve is closest to the piston. Let your finger off the valve, set your dial indicator to 0 and press the valve with your finger again until it contacts the piston. Note the measurement on the indicator and that will be your p/v for the intake valve. Turn the motor over to TDC on the compression stroke and repeat the procedure for the exhaust valve. it will be closest as it is closeing, so you'll see it opening, then start to close, that is when you should start to measure it. The exhaust valve is closest when the piston is chasing the valve up, and the intake is closest when the valve is chasing the piston down.
08-25-2005, 07:48 PM
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Ok, that sounds logical but sort of difficult can't I use the clay method? I don't have the tools required to check it that way.
Either way, I'm at a standstill since I can't get a wrench in there to turn the crank!
Do I dare use the ignition for a second?
Either way, I'm at a standstill since I can't get a wrench in there to turn the crank!
Do I dare use the ignition for a second?
08-26-2005, 06:43 AM
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ill probably get bitched at for this but when i did my last heads/cam swap i used clay...i just snugged a couple of heads bolts and setup the valvetrain on that one cylinder and turned over the motor a few times. i know the lifter isnt pumped up so its not a true test, but i used a damn good thickness of clay to get an idea how close my ptv really was. the valves made no marks so i considered it safe and went ahead and finished it up with no problems.
cam is in sig....used with unmilled 5.3 liter heads, stock mls gasket.
cam is in sig....used with unmilled 5.3 liter heads, stock mls gasket.
08-26-2005, 09:16 AM
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I am in the same boat for checking p-v clearance. However, I think the non-clay method is the most accurate. One tip I got from Brent at TEA was to just set the head down without a gasket and measuer the p-v clearance, then add the thickness of the gasket (.052" for stock GM gaskets). Then you wont compress and/or damage your new gaskets.
08-26-2005, 02:36 PM
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Originally Posted by Z06-Dave
The heads have been milled to 64cc's
You couldn't even go with the 59 cc? 
Talk about Mr. Conservative...LOL. You can get 93 octane in Allentown.You shouldn't have clearance issues with that "baby" cam.
When mine was done they didn't need to flycut (they did check for clearance), and I have the 59 cc heads with a "man's cam," though it is only a 114. 
Oh, and if you do want to measure, try bubble gum rather than clay....LOL.
08-26-2005, 03:43 PM
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Originally Posted by Geneus
What a wuss. You couldn't even go with the 59 cc? Talk about Mr. Conservative...LOL. You can get 93 octane in Allentown.
You shouldn't have clearance issues with that "baby" cam. When mine was done they didn't need to flycut (they did check for clearance), and I have the 59 cc heads with a "man's cam," though it is only a 114.
Oh, and if you do want to measure, try bubble gum rather than clay....LOL.
You couldn't even go with the 59 cc? Talk about Mr. Conservative...LOL. You can get 93 octane in Allentown.You shouldn't have clearance issues with that "baby" cam.
When mine was done they didn't need to flycut (they did check for clearance), and I have the 59 cc heads with a "man's cam," though it is only a 114. Oh, and if you do want to measure, try bubble gum rather than clay....LOL.
Don, any idea what size gasket they used???
Mayday...Mayday...Help!
Anyone...Anyone....
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08-26-2005, 03:51 PM
#9
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Originally Posted by ninobrn99
that cam should clear fine. if a f13 can clear why couldnt the tr230?
Does it matter which way I spin the motor?? I am going clockwise...
08-26-2005, 04:21 PM
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No, it is not torqued to spec, I only install the 4 bolts surrounding the piston I am working on, it would take forever to put all of them in. I am just snugging up the bolts.
I don't know what a "PR" is.
The springs are the ones that come on the AFR's.
Dave
I don't know what a "PR" is.
The springs are the ones that come on the AFR's.
Dave
08-26-2005, 05:35 PM
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When I bolt the stock heads back on with the cometic's I hit the valve too now. I guess the thinner gasket is the guilty party? Was I even safe the way I was running?
08-26-2005, 05:43 PM
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I still dont understand how your .040 cometic gasket doesnt clear that cam. The stock MLS gasket is .052 i believe. .012 clearance is not enough even with your stock heads and that cam. Whats the lift on that cam?
Im running a .600" lift cam and have no clearance issues.
Dixit
Im running a .600" lift cam and have no clearance issues.
Dixit
08-26-2005, 06:00 PM
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Originally Posted by Dixit
I still dont understand how your .040 cometic gasket doesnt clear that cam. The stock MLS gasket is .052 i believe. .012 clearance is not enough even with your stock heads and that cam. Whats the lift on that cam?
Im running a .600" lift cam and have no clearance issues.
Dixit
Im running a .600" lift cam and have no clearance issues.
Dixit
INT EXH
Gross Valve Lift .592 .571
Duration @ .006 Tappit Lift .279 .281
Valve Timing OPEN CLOSE
@ .050 INT 7 BTDC 43 ABDC
EXH 50 BBDC 2- ATDC
108.0 Intake Center Line
INT EXH
Duration @ .050 230 228
Lobe Lift . 3480 .3360
LSA 112.0
08-26-2005, 07:22 PM
#18
Something isn't right. Either your cam card is WAY off or you doing something wrong. That cam will clear stock heads with no damn gasket. LOL
Something isn't right.
If you have a friend close that has some experience have him come over and check everything out.
BTW Dixit Lift hardly matters in P/V clearence.
Something isn't right.
If you have a friend close that has some experience have him come over and check everything out.
BTW Dixit Lift hardly matters in P/V clearence.
08-26-2005, 07:31 PM
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Originally Posted by JZ'sTA
Something isn't right. Either your cam card is WAY off or you doing something wrong. That cam will clear stock heads with no damn gasket. LOL
Something isn't right.
If you have a friend close that has some experience have him come over and check everything out.
BTW Dixit Lift hardly matters in P/V clearence.
Something isn't right.
If you have a friend close that has some experience have him come over and check everything out.
BTW Dixit Lift hardly matters in P/V clearence.
08-26-2005, 07:54 PM
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The AFR heads cleared with the stock gasket. I must have been running some close intake clearance numbers (<.012)...
Can I even get a gasket thick enough to be safe? I don't want to flycut...
Can I even get a gasket thick enough to be safe? I don't want to flycut...