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How much vertical (up and down) play is acceptable in a distributor? Mine seems to have a good amount, maybe 1/16" of an inch or a little more. I was timing my car with my trusty Craftsman tools which has a tach on it, and every once and a while my RPM's would dip significantly. The timing light would also flash unevenly like it was missing a spark every so often. I'm wondering if it's just my 20 year old equipment or if my distributor is screwed up. The distributor is just a stock GM unit on a 350/300HP L48.

If I have to add some shims, where can I get them?
 

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Mark;

I usually shim mine to @.015~.020", most factory units are very "loose".
In testing on a distributor machine many years ago I found this helped stabilize dwell readings.
I can't remember who has the shims but can look up the info if you need.

Hope this helps;

John
 

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I always shim them to remove the play. Around .007"-.015" is fine. I get the shims at the speed shop blister pack isle. :cool:

The distributors come that way when new from GM. NOBODY has ever offered a decent explanation as to why.


They also forget to tell you about the dimple on the drive gear. It needs to face the direction of the rotor tip in order to index correctly. Just a little assembly tip.


-Mark.
 

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Originally posted by stingr69:

They also forget to tell you about the dimple on the drive gear. It needs to face the direction of the rotor tip in order to index correctly. Just a little assembly tip.


-Mark.
Thanks Mark - forgot to mention that - and while we're at it...
Don't forget to check and 'de-burr' the end of the shaft where it enters the oil pump slot - they can have some nasty burrs here that can effect the smoothness of the pump drive and lead to spark-scatter issues.
Oh - and use a steel collar instead of the plastic one if possible.

And one last thing - use a new roll pin and make sure it is driven in correctly (support the gear) and fully - I have seen more than one sticking out some


John
 
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