View Full Version : Lift Vs. Valvetrain Clearance on particular setup.
PaulFiveOh
05-16-2008, 09:33 PM
Stock Edelbrock Performer RPM heads
1.6 RR
.535 Intake
.544 Exhaust
Dur. -(I)284 (E).290 (LS) 114
Can any one tell me, with out measuring, if that setup will fit?
Also, can someone also estimate if the setup will work or not work with 1.72RR
Thanks
k062693w
05-16-2008, 10:25 PM
Take the lift of your cam, divide that by 1.6, and multiply the result by 1.7.
Example
.500" lift is valve lift (w/ 1.6:1 rocker arm ratio)
.500 / 1.6 = .3125
.3125" is lobe lift (regardless of rocker arm ratio)
.3125 x 1.7 = .53125
.53125" is valve lift (w/ 1.7:1 rocker arm ratio)
So if your cam is .535 .544 / 1.6 = .334 .340
And going to 1.72's changes lift to .574 .584
I'm no expert, but with stock pistons that is a ton of lift
But either way above is the formula for figuring the difference in rocker lift
PaulFiveOh
05-16-2008, 10:28 PM
Thanks.
Any one else know if this will clear with those heads?
Really it is fairly easy to check and it is worth it for the peace of mind to just check it. Just make a solid lifter and check it out. With that kind of lift I doubt there is gonna be any clear cut answer without checking, there are so many factors that come into play that it is hard to know.
5.0calypso93lx
05-17-2008, 09:25 AM
Really it is fairly easy to check and it is worth it for the peace of mind to just check it. Just make a solid lifter and check it out. With that kind of lift I doubt there is gonna be any clear cut answer without checking, there are so many factors that come into play that it is hard to know.
x2. Don't guess. Just measure and do it right so you know you aren't going to have any issues. What kind of pistons? Those heads have 2.02/1.60 valves?
PaulFiveOh
05-17-2008, 10:15 AM
I'm pretty sure the heads are 1.90 1.60. It's stock 87-92 (Factory Forged) pistons.
5.0calypso93lx
05-17-2008, 10:48 AM
I'm pretty sure the heads are 1.90 1.60. It's stock 87-92 (Factory Forged) pistons.
I know the general rule of thumb is that anything under .550 lift on the stock heads and pistons, is ok. You are close to that with bigger valved heads, so I would definitely check. No two engines are the same.
satan jamez
05-17-2008, 11:17 AM
Stock Edelbrock Performer RPM heads
1.6 RR
.535 Intake
.544 Exhaust
Dur. -(I)284 (E).290 (LS) 114
Can any one tell me, with out measuring, if that setup will fit?
Also, can someone also estimate if the setup will work or not work with 1.72RR
Thanks
My Jay Allen custom cam has 564/553 lift with 1.72 RR. 114 LS but my duration is less 218/230 @ .050" Stock 88 bottom end 5.0, cam installed straight up. Hope that helps.
mustangrfast88
05-17-2008, 04:08 PM
i would say no i would measure and no 2 engines are the same
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