317 heads that I just got have .030 longer exhaust valves
06-10-2010, 07:57 PM
#1
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317 heads that I just got have .030 longer exhaust valves can any body help with some info about why the valves on the exhaust would be .030 longer than the intake valves I posted all of the specs the heads were ported and larger valves installed but with the fact that the exhaust valves are longer wont that be a problem with the valve adjustment ?? if I put these heads on and just run the rockers down what happens at high rpm when the lifters pump all the up wont they hit the piston
ALSO THESE HEADS WERE BEING BUILT FOR A SUPERCHARGER FROM WHAT I WAS TOLD
specs on heads
flow #
intake 0.6000 lift 273.6 ccfm after that it goes down
exhaust 0.7000 lift 220.2 ccfm after that it goes down
69.8 cc combustion chamber
valves
intake 202
ehaust 1.575
any info that might help would be good
ALSO THESE HEADS WERE BEING BUILT FOR A SUPERCHARGER FROM WHAT I WAS TOLD
specs on heads
flow #
intake 0.6000 lift 273.6 ccfm after that it goes down
exhaust 0.7000 lift 220.2 ccfm after that it goes down
69.8 cc combustion chamber
valves
intake 202
ehaust 1.575
any info that might help would be good
06-10-2010, 11:13 PM
#3
Well, obviously it's going to change the spring installed height. You can shim the springs .030 to get back to the correct seat pressures. You may not have to shim the rockers, but you can check rocker wipe.. If it's normally narrow and centered on the valve tip then you may just need a different pushrod length on the exhaust valves. If it is not centered or is wide to the edges, then you will need to shim the rockers until you get the desired wipe pattern. You will probably still need different push rods for the exhaust.
06-12-2010, 12:46 PM
#5
That's usually not a good idea. A lot of times, the tip is hardened to take the abuse to the rocker scrubbing or slamming against the valve, so grinding off .030" may remove that hardened tip, especially if you don't know how much has been ground off already.
I'm getting the impression that the intake valves got new seats installed, while the exhaust valves were just sunk in a little further when the shop did a valvejob. It's probably manageable with an aftermarket rocker and two different length pushrods.
I'm getting the impression that the intake valves got new seats installed, while the exhaust valves were just sunk in a little further when the shop did a valvejob. It's probably manageable with an aftermarket rocker and two different length pushrods.
06-12-2010, 01:11 PM
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That's usually not a good idea. A lot of times, the tip is hardened to take the abuse to the rocker scrubbing or slamming against the valve, so grinding off .030" may remove that hardened tip, especially if you don't know how much has been ground off already.
I'm getting the impression that the intake valves got new seats installed, while the exhaust valves were just sunk in a little further when the shop did a valvejob. It's probably manageable with an aftermarket rocker and two different length pushrods.
I'm getting the impression that the intake valves got new seats installed, while the exhaust valves were just sunk in a little further when the shop did a valvejob. It's probably manageable with an aftermarket rocker and two different length pushrods.
Man I sure do miss having valves with stellite tips.
