Distributor Shaft--end play?
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Distributor Shaft--end play?
Chasing a low RPM engine miss-fire problem with my 87 vert. Checked the play in the distributor shaft based on a friend's suggestion. There is no lateral play but there is end-play [vertical]--feels like shaft gear is able to climb the cam gear so rotor comes up maybe 1/8 to 3/16 and rotates perhaps another 1/8 to 3/16 based on verticle movement between gears. Is there a spec on this--how much play is too much? Is there a bushing that can be replaced vs the whole distro/shaft assembly?
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Joined: Aug 2007
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From: WV
When I bought my new DUI distributor it had .035 end play .. I talked to Pete K my engine builder, and he had me buy a shim kit and shim it to .015. I could of gone to .010 but I figured for a low rpm street car it wasn't neccesary.. I really doubt that end play is what's causing your miss unless it's real bad,because like Cliff says above, centrifugal force causes it to go to zero when it spins.Shimming end play is used to stop "spark scatter" which can often happen at high rpms..
When you start messing with end play you have to be careful, if you shim the shaft to tight and the dizzy gear binds with the cam gear you can cause gear damage. After shimming the shaft you have to install the dizzy without the gasket, making sure it drops all the way down onto the manifold, then make sure you still have some up and down movement in the shaft. If there is no up and down movement, then you have to get a different shim kit to raise the dizzy up off the manifold to remove the binding of the gears. This is why the factory puts so much end play in there distributors , so there's alway enough play so the gears don't bind...WW
When you start messing with end play you have to be careful, if you shim the shaft to tight and the dizzy gear binds with the cam gear you can cause gear damage. After shimming the shaft you have to install the dizzy without the gasket, making sure it drops all the way down onto the manifold, then make sure you still have some up and down movement in the shaft. If there is no up and down movement, then you have to get a different shim kit to raise the dizzy up off the manifold to remove the binding of the gears. This is why the factory puts so much end play in there distributors , so there's alway enough play so the gears don't bind...WW
Last edited by WW7; Nov 20, 2012 at 08:09 AM.
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