Pushrod length different pass. vs driver banks?
02-28-2010, 08:14 PM
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Pushrod length different pass. vs driver banks? Has anyone had pushrod lengths come up different from one side of the motor vs the other? I am seeing a fifteen thousandths difference when I measure with the PR checker. I measured from the deck of the block to the valvecover surface on both heads they come up within a thousandth of each other so sorta rules out milling differences in the heads themselves. They are L92 heads. The intakes vs the exhuasts were different lengths as well but I have seen and read of others having that happen so I was not as concerned with that. Just odd to see one side (passenger) needing a fifteen thous. longer pushrod than the other (drivers) Anyone ever run into this?.
03-01-2010, 06:40 AM
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The heads are on the motor now. It's a project I am helping a close friend with. It is on a Texas Speed 418 shortblock and a set of the Texas Speed ported L92 heads. I am not sure if those guys deck the blocks they build. My first thought was one head possibly being milled more than the other hence my measuring the deck to valvecover surface and they come up within a thousandth. Other possibilities are valves on one head being hung a bit deeper into the seats than the other ,pedestals are off,pedestal mounting surface on the head itself. I could always just shim one set of pedestals up the 15 thous. and order matching sets of PR's but I would really like to know WHY.
The intake valves are hollow stems and are not GM (I dont think) and would probably explain my difference in regards to the intake vs exhaust relationship differences. Vette I am not following the rocker pad height to the valvestem measurement. I was thinking of trying to remove a set of springs from each side and measuring the distance from the top of the valveguide to the top of the valve stem and compare. That would rule out one head having the seats a bit deeper than the other? This kinda **** makes me lose my mind god bless all you guys that do this everyday lol.
The intake valves are hollow stems and are not GM (I dont think) and would probably explain my difference in regards to the intake vs exhaust relationship differences. Vette I am not following the rocker pad height to the valvestem measurement. I was thinking of trying to remove a set of springs from each side and measuring the distance from the top of the valveguide to the top of the valve stem and compare. That would rule out one head having the seats a bit deeper than the other? This kinda **** makes me lose my mind god bless all you guys that do this everyday lol.
03-01-2010, 12:15 PM
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The heads are on the motor now. It's a project I am helping a close friend with. It is on a Texas Speed 418 shortblock and a set of the Texas Speed ported L92 heads. I am not sure if those guys deck the blocks they build. My first thought was one head possibly being milled more than the other hence my measuring the deck to valvecover surface and they come up within a thousandth. Other possibilities are valves on one head being hung a bit deeper into the seats than the other ,pedestals are off,pedestal mounting surface on the head itself. I could always just shim one set of pedestals up the 15 thous. and order matching sets of PR's but I would really like to know WHY.
The intake valves are hollow stems and are not GM (I dont think) and would probably explain my difference in regards to the intake vs exhaust relationship differences. Vette I am not following the rocker pad height to the valvestem measurement. I was thinking of trying to remove a set of springs from each side and measuring the distance from the top of the valveguide to the top of the valve stem and compare. That would rule out one head having the seats a bit deeper than the other? This kinda **** makes me lose my mind god bless all you guys that do this everyday lol.
The intake valves are hollow stems and are not GM (I dont think) and would probably explain my difference in regards to the intake vs exhaust relationship differences. Vette I am not following the rocker pad height to the valvestem measurement. I was thinking of trying to remove a set of springs from each side and measuring the distance from the top of the valveguide to the top of the valve stem and compare. That would rule out one head having the seats a bit deeper than the other? This kinda **** makes me lose my mind god bless all you guys that do this everyday lol.
I think you and I are speaking of the same measurements. Sounds like either the valves are deeper or the rocker pedestal location is different. Since the valves have been worked, I think my first suspicion would be there.
03-01-2010, 09:22 PM
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Thanks, it had to do with the rocker peds. I swapped the ped rails out and oddly enough the numbers have come closer in line with each other. Sometimes **** makes no sense but i'm not gonna argue with it. FWIW 3/8 pushrods clear the L92 heads with relative ease.
