What is the maximum lift for an aftermarket cam before the valves hit the piston? The motor is out of a 72 stock everything. open chamber heads (I think).
Thanks Will
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I would think that anything over .600 COULD be at risk. I ran a .605 on the intake, .581 on the exhaust with pop uu TRW pistons and had, if memory serves me right, .100 clearance.
The only safe thing to do if you need to run maximum lift is to measure the clearance with clay.
The NASCAR guys run lifts up near .700 (.680+) but they flycut the pistons for clearance. They say that you need to do that to make 600hp but from what I have seen with the Desk Top dyno there isn't much to be gained in a Cleveland over about .581.
The only safe thing to do if you need to run maximum lift is to measure the clearance with clay.
The NASCAR guys run lifts up near .700 (.680+) but they flycut the pistons for clearance. They say that you need to do that to make 600hp but from what I have seen with the Desk Top dyno there isn't much to be gained in a Cleveland over about .581.
Shirley..that depends on what pistons, heads and CR you are using?
Here's what I'm dropping in #7024: 393C stroker, flat top pistons 11.3:1 CR, A3 heads with a 0.709" lift mechanical solid roller cam
Here's what I'm dropping in #7024: 393C stroker, flat top pistons 11.3:1 CR, A3 heads with a 0.709" lift mechanical solid roller cam
with clevelands and flat top pistons you can go quite aggressive on lift, keep in mind cam timing also plays a big part in piston to valve clearance.
it sounds like you will be fitting a hydraulic cam, they don't really come any bigger than 600 thou and 250@050 anyway.
it sounds like you will be fitting a hydraulic cam, they don't really come any bigger than 600 thou and 250@050 anyway.
I was just got off the phone with comp cams and they came up with a custom cam grind for my applicatiion:
solid roller
dur @ 50
254in 260ex
lift
671 in .020lash
678 ex .022 lash
lobe ctr
110 +4
3000-7000+ power
what are you thoughts?
Daniel
solid roller
dur @ 50
254in 260ex
lift
671 in .020lash
678 ex .022 lash
lobe ctr
110 +4
3000-7000+ power
what are you thoughts?
Daniel
You are going to probably need a competition type cylinder head in that you will need to a taller valve spring to provide a greater assembly height so that the bottom of the spring keeper doesn't bottom out on the top of the valve guide.
The comp head would accomodate the taller spring without necssarily needing longer valve stems then stock.
Of course you could probalby spec just about any valve length you want in titanium valves and solve a lot of the problem.
I would expect custom length push rods as well for correct geometry.
I would expect more rapid valve guide wear and would be concerned for a greater potential for catastrophic valve train failure due to added stress on the valve train components.
That's alot of duration for a street engine. What displacement is it and is it a race only engine?
The comp head would accomodate the taller spring without necssarily needing longer valve stems then stock.
Of course you could probalby spec just about any valve length you want in titanium valves and solve a lot of the problem.
I would expect custom length push rods as well for correct geometry.
I would expect more rapid valve guide wear and would be concerned for a greater potential for catastrophic valve train failure due to added stress on the valve train components.
That's alot of duration for a street engine. What displacement is it and is it a race only engine?
I'm looking to replace the cam and lifters in a motor that is bone stock. I don't want to change anything else. There is a sticky lifter in there and I thought I would throw a new cam in there at the same time to give it a bit of growl.
Has anyone installed a, lets say, comp cams 266 or 268 without any issues with valve clearence or other problems?
Will
Has anyone installed a, lets say, comp cams 266 or 268 without any issues with valve clearence or other problems?
Will
Checkout crower cams or crane cams, they give a good description, I ended up with a solid roller cam for mine, difference would be closed chamber heads
Mark
Mark
quote:Shirley..that depends on what pistons, heads and CR you are using?
Here's what I'm dropping in #7024: 393C stroker, flat top pistons 11.3:1 CR, A3 heads with a 0.709" lift mechanical solid roller cam
WOO HOO!!!and dont call me Shirley...when I built my open chamber motor, I was running 12.5:1 TRW Power Forged pistons, and a .586" liftComp Cams Super Stock Camshaft. I had to advance the cam 4 degrees to maintain .100" clearance.
Jeff
