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2.9 valves.
- Thread starter conanhomer
- Start date
Barry
Diamond Level Sponsor
The situation shown in the picture suggests that something (???) in the valve train is way off. The shorter 2.9 valves should add about 0.030" to the total valve lash and the reground cam base circle could potentially add another 0.060" to 0.090" for a total increase of about 0.120" to 0.150". Decking the block and milling the head should reduce the valve lash increase by twice the total amount of material removed (e.g.; 0.010 + 0.010" = 0.020" x 2 = 0.040" total lash reduction). Changing the head gasket thickness also affects total valve lash by twice the amount of the thickness change. I would not be surprised to see the total valve lash increase by 0.060" to 0.120", but the picture suggests a MUCH larger increase. Some possible reasons could include:
Lots of questions and not many answers.
Too much camshaft base circle reduction?
Wrong lifters?
Wrong pushrods?
Wrong rocker arms?
Wrong rocker shaft stands?
Extremely thick head gasket?
Worn rocker arm bores?
Worn rocker arm shafts?
Wrong lifters?
Wrong pushrods?
Wrong rocker arms?
Wrong rocker shaft stands?
Extremely thick head gasket?
Worn rocker arm bores?
Worn rocker arm shafts?
Lots of questions and not many answers.
Last edited:
conanhomer
Donation Time
i am still using the stock lifters, pushrods and rocker assemblies. stock head gasket from Fel Pro. i have a Delta grind cam done to Jose's specs.
there has never been a problem with this setup, so i'm thinking the shop may have not recessed the valve seats properly.
there has never been a problem with this setup, so i'm thinking the shop may have not recessed the valve seats properly.
I had the impression that raised valve seats offered a performance advantage, although it would be a small advantage.
The first shop that worked on my heads left the valve heights all over the place. I took the heads to another shop, Portland Engine Rebuilders (since reorganized under a new name), that has a Serdi valve seat machine. Ted King used to tune Cologne V6 engines for racing. They ported my heads and fixed the valve height issue.
Heads are where power is made.
The first shop that worked on my heads left the valve heights all over the place. I took the heads to another shop, Portland Engine Rebuilders (since reorganized under a new name), that has a Serdi valve seat machine. Ted King used to tune Cologne V6 engines for racing. They ported my heads and fixed the valve height issue.
Heads are where power is made.
conanhomer
Donation Time
my machine shop is going ahead with cutting the rocker towers down by .035. They are also cleaning up the spring wear on the shafts, and refacing the rocker arms. if this doesn't work at least we haven't ruined much and can get other rocker assemblies.
conanhomer
Donation Time
update on my valvetrain. the machine shop shaved my rocker towers and reconditioned my rockers. everything works great now.
the geometry is within specs too. i still don't know what put it all out of whack, but it's fixed now so i will leave it alone.
thanks again for all the advice/info.
the geometry is within specs too. i still don't know what put it all out of whack, but it's fixed now so i will leave it alone.
thanks again for all the advice/info.