PTV clearance??
08-06-2007, 10:57 PM
#1
PTV clearance?? I just got my short block back today and Im worried now that Im going to have piston to valve clearance issuse. Its a 383 short block. the block was decked and my heads are milled. Now my pistons sit .010 out of the hole. My heads have 2.05/1.60 valves and I'm dead on .600 lift at the valve. I was planning on running the .029 thick Impala head gasket which I alread have but not yet installed. Should I go with a thicker head gasket? any help is greatly apreciated!!
08-07-2007, 12:56 AM
#3
max lift has absolutely nothing to do with valve clearance. the lsa of the cam and how much duration and how agressive the lobes are will define your ptv clearance.
btw if your pistons are +.010 out of the hole and you try to use a .029" gasket you're gonna have worse problems than ptv clearance. because you'll be running a quench of .019" and the pistons will hit the heads. the tightest i have ever run was about .030" and it was a drag race only piece but you really have to watch piston rock etc etc etc to run it that tight and its certainly not for applications that will see any substantial use. also the power difference between .030" and the .045" quench i was running before was exactly dick. car ran and mph the same as the season before.
btw if your pistons are +.010 out of the hole and you try to use a .029" gasket you're gonna have worse problems than ptv clearance. because you'll be running a quench of .019" and the pistons will hit the heads. the tightest i have ever run was about .030" and it was a drag race only piece but you really have to watch piston rock etc etc etc to run it that tight and its certainly not for applications that will see any substantial use. also the power difference between .030" and the .045" quench i was running before was exactly dick. car ran and mph the same as the season before.
08-07-2007, 06:56 PM
#6
Originally Posted by 96capricemgr
Still too tight, I would try something more like the stock GM .049.
Frankly though I would be upset the block was cut that far, unless you told them too.
Check the PTV, that is the ONLY way you will know.
Frankly though I would be upset the block was cut that far, unless you told them too.
Check the PTV, that is the ONLY way you will know.
08-07-2007, 07:21 PM
#7
Originally Posted by BarneyMobile
Will that gasket hold up. Its a 383 with the LE3 setup.
Good luck, Ed
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08-07-2007, 07:31 PM
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.010 out of the hole with a .029 gasket is a bad idea. Have been running .022 piston to head clearance and find a ever so small touching of the head and piston.
08-07-2007, 10:20 PM
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What is the best way to find out all of your #'s and make this decision? I am having my block 0 decked, but what #'s am I needing to make the proper calculation for gasket thickness and proper quench (street creeper/strip)? I too am building a LE3 383, and needed to know how much normally gets milled off of the heads from Lloyd. I am very certain they had never been milled before. Not trying to hijack barney m, but since we are on the same page here, figure I would ask.
08-07-2007, 11:08 PM
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Originally Posted by 92LT1RS
call/e-mail lloyd and ask him.
, but was curious as to what the norm was for milling a stock set. Being that he is running the same heads, figured he might know.
08-08-2007, 01:21 AM
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Originally Posted by 97LT1
What is the best way to find out all of your #'s and make this decision? I am having my block 0 decked, but what #'s am I needing to make the proper calculation for gasket thickness and proper quench (street creeper/strip)? I too am building a LE3 383, and needed to know how much normally gets milled off of the heads from Lloyd. I am very certain they had never been milled before. Not trying to hijack barney m, but since we are on the same page here, figure I would ask.
08-08-2007, 10:49 AM
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My 383 was the same way as your's. Zero decked, milled stage II heads ( larger valves). I have dished blower pistons with valve reliefs.
I run a 550 lift cam and had to use commetic .055 gaskets to get the clearance I needed. (Block and heads also needed to be properly surfaced for them to seal! ). I wanted a min. of .100 clearance on the intake and ended up just under that.
That doesn't mean your engine is identical to mine, just means you really need to check.
Just remember you need to check when the piston is closest to the open valve which may not be TDC. PVC is often closest 3-4 degrees past TDC. Easiest way is to use some moddling clay on the piston, assemble, turn it over, disassembly and mic. the clay. Or use test springs, a degree wheel and a dial indicator.
You will likely need different lenght pushrods and your intake milled so it fits properly and doesn't leak.
JB
I run a 550 lift cam and had to use commetic .055 gaskets to get the clearance I needed. (Block and heads also needed to be properly surfaced for them to seal! ). I wanted a min. of .100 clearance on the intake and ended up just under that.
That doesn't mean your engine is identical to mine, just means you really need to check.
Just remember you need to check when the piston is closest to the open valve which may not be TDC. PVC is often closest 3-4 degrees past TDC. Easiest way is to use some moddling clay on the piston, assemble, turn it over, disassembly and mic. the clay. Or use test springs, a degree wheel and a dial indicator.
You will likely need different lenght pushrods and your intake milled so it fits properly and doesn't leak.
JB
Last edited by Pampered-Z; 08-08-2007 at 10:55 AM.
