Pushrod and preload
Pushrod and preload Little car history
02 formula
241 heads milled .015
226-230 eps cam
Ls7 lifter
Gm mls gaskets
Stock rocker with trunion upgrade
Stock short block
I been chasing a tap for months. Finally getting somewhere.
Car had 7.425 trickflows pushrods that measured 7.44 end to end
I put some comp 7.4 in it. The comps measure 7.408 end to end
Same tap but sounds a bit softer. So after this I got a pushrod length checker. I measured 7.298 end to end for zero preload. So I'm thinking I should have a 7.35 or so in it. What are y'all's thought on this.
02 formula
241 heads milled .015
226-230 eps cam
Ls7 lifter
Gm mls gaskets
Stock rocker with trunion upgrade
Stock short block
I been chasing a tap for months. Finally getting somewhere.
Car had 7.425 trickflows pushrods that measured 7.44 end to end
I put some comp 7.4 in it. The comps measure 7.408 end to end
Same tap but sounds a bit softer. So after this I got a pushrod length checker. I measured 7.298 end to end for zero preload. So I'm thinking I should have a 7.35 or so in it. What are y'all's thought on this.
Milled heads will need shorter pushrods, and LS7 lifters too generally need shorter pushrods. Not sure why you were running longer than stock ones. When using the pushrod length checker, just count the turns to find the length. Don't measure end-to-end. Comp does not use end-to-end length for their pushrods, they use a gauge length.
So with the length checker, assuming you're using Comp 7702, count the turns to zero lash and multiply by 0.05, add 6.8, add desired preload, and boom that's the pushrod length you need. Order them from Comp so you know you're getting the right length.
FWIW, with my heads milled 0.022, LS7 lifters, stock thickness head gaskets, stock base circle cam, and stock rockers with upgraded trunions, I'm running Comp 7.325" pushrods for ~0.075" preload.
So with the length checker, assuming you're using Comp 7702, count the turns to zero lash and multiply by 0.05, add 6.8, add desired preload, and boom that's the pushrod length you need. Order them from Comp so you know you're getting the right length.
FWIW, with my heads milled 0.022, LS7 lifters, stock thickness head gaskets, stock base circle cam, and stock rockers with upgraded trunions, I'm running Comp 7.325" pushrods for ~0.075" preload.
That sounds about right. It looks like I should go with a 7.35
On a side note it looks like trick flow uses guage length and comp does end to end. I have pics of the measurement.
Comp 7.4 measured 7.408 end to end useing calipers
Trickflows 7.425 measured 7.44 end to end useing calipers also.
Just my measurements.
That being said I took the 7.298 measurement useing calipers and s trickflow lenth checker. The measurement was also end to end just like the rest of the measurements I took.
On a side note it looks like trick flow uses guage length and comp does end to end. I have pics of the measurement.
Comp 7.4 measured 7.408 end to end useing calipers
Trickflows 7.425 measured 7.44 end to end useing calipers also.
Just my measurements.
That being said I took the 7.298 measurement useing calipers and s trickflow lenth checker. The measurement was also end to end just like the rest of the measurements I took.
Last edited by BKsNHRA; Jan 26, 2013 at 02:49 PM.
for what its worth....I just installed a set of Livernois STG 3 243 heads on my car that were milled .012. After measuring multiple times, I came up with 7.375 for the proper preload on the LS7 lifters. Car runs great, and no unusual valve train noise. 
