Quick PTV ??
04-14-2010, 12:03 PM
#1
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Quick PTV ?? Anyone with a 240* .595 or bigger cam with stock heads and bottom end LS2.
Did you check your PTV and how was it?
Did you check it with the hyd. lifter?
Any problems?
How did you correct them?
Anyone know how much plunger movement there is in a stock hyd lifter?
As you may have guessed by these questions I checked mine. I did not have a solid lifter or check springs. I'm close to .100 on the intake and over .100 on the exh. I'd like a bit more. I'm running stock head gaskets with a crush thickness of .051. I see Cometic has a .086 available, but I don't have time to change them before my tune on Sunday.
Did you check your PTV and how was it?
Did you check it with the hyd. lifter?
Any problems?
How did you correct them?
Anyone know how much plunger movement there is in a stock hyd lifter?
As you may have guessed by these questions I checked mine. I did not have a solid lifter or check springs. I'm close to .100 on the intake and over .100 on the exh. I'd like a bit more. I'm running stock head gaskets with a crush thickness of .051. I see Cometic has a .086 available, but I don't have time to change them before my tune on Sunday.
04-14-2010, 11:59 PM
#3
it doesn't matter what someone else has, you still need to measure. every engine can be different. why risk it?
lift has nothing to do with PTV clearance. think about where the piston is when the valve is at full lift. duration, lsa, etc are more of a factor. one cam with 240 @ .050 may have a significant amount of clearance more than another cam with 240 @ .050. it depends on the valve events.
if you have .100 on intake and exhaust, you are fine, but with normal springs and a hydraulic lifter you are going to push the plunger down in the lifter which will give you inaccurate readings. you can grab checking springs from home depot or lowes for 3 dollars. clay it and don't waste any more of your time or money. if you change head gaskets you will totally screw up your quench which will make your engine a significant amount more prone to detonation, and you will lose a good bit of compression.
lift has nothing to do with PTV clearance. think about where the piston is when the valve is at full lift. duration, lsa, etc are more of a factor. one cam with 240 @ .050 may have a significant amount of clearance more than another cam with 240 @ .050. it depends on the valve events.
if you have .100 on intake and exhaust, you are fine, but with normal springs and a hydraulic lifter you are going to push the plunger down in the lifter which will give you inaccurate readings. you can grab checking springs from home depot or lowes for 3 dollars. clay it and don't waste any more of your time or money. if you change head gaskets you will totally screw up your quench which will make your engine a significant amount more prone to detonation, and you will lose a good bit of compression.
04-15-2010, 08:06 AM
#4
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Good morning bump
I realize not all is the same, I do understand valve/piston timing events and cam profiles may be different from identical engines and cams and what-nots.
I mostly wanted to know how much others have and if they have had any issues with running them close to, or below, .100.
On another note: It's running and no issues so far. I haven't tacked it past 3500. I've got my fingers crossed and will be getting it tuned Sun. After that I'll find my ck. springs or purchase new heads, pistons, etc...... and do It over.
I'd still like to know how low people have gone and if they have had issues.
I realize not all is the same, I do understand valve/piston timing events and cam profiles may be different from identical engines and cams and what-nots.
I mostly wanted to know how much others have and if they have had any issues with running them close to, or below, .100.
On another note: It's running and no issues so far. I haven't tacked it past 3500. I've got my fingers crossed and will be getting it tuned Sun. After that I'll find my ck. springs or purchase new heads, pistons, etc...... and do It over.
I'd still like to know how low people have gone and if they have had issues.
04-15-2010, 10:43 PM
#5
if you have .100 on both the intake and exhaust you will not have an issue. some guys have run and raced engines with as little as .040 intake clearance. exhaust is the most important considering the piston is chasing the valve up, but with .100 clearance you are safe.