Can proper pushrod length be figured, rather than measured?
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iTrader: (11)
Joined: Mar 2002
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From: East Central Florida
Can proper pushrod length be figured, rather than measured? All the method threads I've seen, want the use of the
pushrod length measuring tool.
Can proper pushrod length be figured, rather than measured,
and gotten right? Here's the deal. I have all the pieces for
a heads & cam swap. It's a real mix of stuff; 317 heads with
Z06 valves, a Lunati baby cam, all going on undecked. I know
the Z06 valves are longer stems, I don't know the Lunati base
circle but can mic it. My question is, can pushrods be figured
from individual measurements? I don't want to show up with
the pushrod sets I've got, only to find that I need to order
something else and have the car sitting tore-apart all the
while. But I also can't do the usual on-car (or on-motor)
measurement before the head swap on this daily driver. I
am looking for a way to make this not-a-hangup.
Can it be done using some head-off measurement plus the
base circle value? Or just add (subtract?) the valve stem
difference of the Z06 valves and add (subtract?) the base
circle of the Lunati cam from my stock stackup?
pushrod length measuring tool.
Can proper pushrod length be figured, rather than measured,
and gotten right? Here's the deal. I have all the pieces for
a heads & cam swap. It's a real mix of stuff; 317 heads with
Z06 valves, a Lunati baby cam, all going on undecked. I know
the Z06 valves are longer stems, I don't know the Lunati base
circle but can mic it. My question is, can pushrods be figured
from individual measurements? I don't want to show up with
the pushrod sets I've got, only to find that I need to order
something else and have the car sitting tore-apart all the
while. But I also can't do the usual on-car (or on-motor)
measurement before the head swap on this daily driver. I
am looking for a way to make this not-a-hangup.
Can it be done using some head-off measurement plus the
base circle value? Or just add (subtract?) the valve stem
difference of the Z06 valves and add (subtract?) the base
circle of the Lunati cam from my stock stackup?
This MAY be right (others please check):
(Stock pushrod length - cylinder head mill) - (stock gasket thickness - new gasket thickness) + ((stock base circle - new base circle) / 2)
Example:
(7.40 - .024) - (.052 - .040) + (.060/2) = 7.3940 (or 7.40 pushrods)
This will give you the pushrod length FOR STOCK LIFTER PRELOAD WITH STOCK ROCKERS. If you have different different lifters and/or rockers, this formula won't be correct.
(Stock pushrod length - cylinder head mill) - (stock gasket thickness - new gasket thickness) + ((stock base circle - new base circle) / 2)
Example:
(7.40 - .024) - (.052 - .040) + (.060/2) = 7.3940 (or 7.40 pushrods)
This will give you the pushrod length FOR STOCK LIFTER PRELOAD WITH STOCK ROCKERS. If you have different different lifters and/or rockers, this formula won't be correct.
Last edited by Byter; Mar 14, 2005 at 11:59 AM. Reason: Had minus instead of plus for last operator.
heres a spread sheet i snatched up a long time ago. i think Levi posted it like 3 years back. dont know how accurate it is or what formula's are used but you can dick around with it
http://ourworld.cs.com/ls1info/p-rod.xls
http://ourworld.cs.com/ls1info/p-rod.xls
Originally Posted by technical
Order two sets of pushrods (7.38&7.4) and return the set you don't use.
