Actual piston to valve clearance

pushlar84

pushlar84

pushlar84
Joined
Dec 19, 2009
Messages
658
Does anyone have a good idea what is a save piston to valve clearance? i clayed one of my pistons with a old head gasket, torqued, and valve train setup properly and i have .065 on the intake and .100 on the exhaust. i flycut the pistons to .060 for starters. did not want to take too much off for starting pusposes. thanks
 
I believe .050 intake and .070 exhaust was the minimun clearance i was told.
 
12 valve or 24/CR
That is more than enough for a 4 valve motor , its close to enough on a 2 valve , would like to see just a little more . This is at zero lash?
There is a way to do this without having to pull the head, using a degree wheel and dial indicator
 
the piston is running away from the valve on intake stroke, the exhaust valve is running from the piston on exhaust stroke.
 
It all has to do with RPM, boost, spring rate and weight of the valve components. I do not like to see anything less than 0.080" on the exhaust and 0.060" on the intakes
 
pushlar84 said:
Does anyone have a good idea what is a save piston to valve clearance? i clayed one of my pistons with a old head gasket, torqued, and valve train setup properly and i have .065 on the intake and .100 on the exhaust. i flycut the pistons to .060 for starters. did not want to take too much off for starting pusposes. thanks
Click to expand...

You have more than enough room. Leave it alone and run it.
 
Last year I got by with .032"/.038", .500" lift cam, #165 springs and 4200rpm. Certainly don't recommend it, but it did work. On the new rebuild I'm shooting for .040", .060".
 
.500" lift ?? Dang, and I was stressing about .333 Intake Lift and .310" Exhaust lift with stock clearances.
 
That is alot of lift. Drothgeb, what does your head flow or do you know? Most stall out far before .500" lift...

Edit: not trying to be rude, just curious.
 
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Don't forget about piston growth with the heat involved. A degree wheel and dial is all you need.
 
Valve lift with my setup should be roughly INT - .4592 and EXT - .4624 and I have a big cam sitting here...
 
I forget you have a 12v head, I'm using a 24v head. Different rocker ratio.
 
On my 12v I'm running a Colt stage 4, .280/.323 cam lift or using 1.75 rr 0.480/0.545 valve lift @ .10/.15 lash.

My ptv cold was 0.047/0.063, So far I've been fine up to 4k with 60lb springs.

Geoff @ Colt Cams was said I'd be fine with my springs, rpm, & PTV clearance.
 
On my 12V
Intake clearance is .046" @ 8* BTDC
Exhaust is .060" @ 4* ATDC
5k gsk

9,000 street miles, multiple dyno runs and zero problems, 796rwhp to date

Hamilton cam and valve train
 
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