Need an estimate on pushrod length
Need an estimate on pushrod length Heres my setup.
stock ls1 block and bottom end
milled ls6 heads to 60cc
morel lifters
yella terra rockers 1.7
228/234 custom cam
I used a checker and came up with 7.4 but I must have done something wrong because when I went to start the engine it has no compression so the valves must be staying open from the pushrods being too long. A shop told me 7.325 would probably work before I came up with the 7.4.
Im tired of messing with a checker and whatnot and I don't really have the time to track one down. Thanks guys
stock ls1 block and bottom end
milled ls6 heads to 60cc
morel lifters
yella terra rockers 1.7
228/234 custom cam
I used a checker and came up with 7.4 but I must have done something wrong because when I went to start the engine it has no compression so the valves must be staying open from the pushrods being too long. A shop told me 7.325 would probably work before I came up with the 7.4.
Im tired of messing with a checker and whatnot and I don't really have the time to track one down. Thanks guys
IIRC, the morels only want ~.025-.030 of preload, which means you'll be reaching full TQ (22 ft lbs) about 3/4 of a turn from zero lash. Set your checker up until you're getting 3/4 turn, and that's where your length is going to be.
As Predator said, if you're really not sure find somebody that is. Valvetrain geometry is probably the most overlooked step of anyone building their own car in their garage. Especially when you've got all these knuckle-headed vendors telling everyone a 7.4 pushrod is the cure-all for any camshaft install.
As Predator said, if you're really not sure find somebody that is. Valvetrain geometry is probably the most overlooked step of anyone building their own car in their garage. Especially when you've got all these knuckle-headed vendors telling everyone a 7.4 pushrod is the cure-all for any camshaft install.
IIRC, the morels only want ~.025-.030 of preload, which means you'll be reaching full TQ (22 ft lbs) about 3/4 of a turn from zero lash. Set your checker up until you're getting 3/4 turn, and that's where your length is going to be.
As Predator said, if you're really not sure find somebody that is. Valvetrain geometry is probably the most overlooked step of anyone building their own car in their garage. Especially when you've got all these knuckle-headed vendors telling everyone a 7.4 pushrod is the cure-all for any camshaft install.
As Predator said, if you're really not sure find somebody that is. Valvetrain geometry is probably the most overlooked step of anyone building their own car in their garage. Especially when you've got all these knuckle-headed vendors telling everyone a 7.4 pushrod is the cure-all for any camshaft install.
Zero lash checker + How much preload you want = ordering size.
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You should specify which Morel lifters you have, the super-expensive ones that want very little preload or the somewhat-less-expensive ones that want a little more preload.
You also didn't specify how much deck thickness was removed from the heads in hundredths or thousandths of an inch...chamber volume isn't useful in this instance.
And "custom cam" without even a lift measurement is also useless for guessing how much smaller the base circle radius would be.
Not that any of that info is going to get you accurate results anyway, just pointing out how ridiculous the question was. You need to read up on how to use the pushrod length tool.
You also didn't specify how much deck thickness was removed from the heads in hundredths or thousandths of an inch...chamber volume isn't useful in this instance.
And "custom cam" without even a lift measurement is also useless for guessing how much smaller the base circle radius would be.
Not that any of that info is going to get you accurate results anyway, just pointing out how ridiculous the question was. You need to read up on how to use the pushrod length tool.
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Verdad Gallardo This 1/4 turn that 1/2 turn this is confusing! Just set the checker to zero lash. ADD the amount of preload you want to length of the measured checker for ordering. KEEP MIND, when you torque a fastener the bolt stretches. Hence, your PR can be at maximum depression and the bolt will still turn. Most likly neglible to the results, but it confuses some people.
Zero lash checker + How much preload you want = ordering size.
Zero lash checker + How much preload you want = ordering size.
1 full turn of an LS1 rocker bolt = .047 preload
.047 x .5 (1/2 turn) = ~.023 preload
.047 x .75 (3/4 turn) = ~.035 preload
It's actually very, very simple. Also, LSX rocker bolts are grade 8 (IIRC), they do not "stretch" @ 22 ft lbs enough to have any adverse effects on preload readings.
Last edited by Damian; May 18, 2012 at 10:45 PM.
