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dist gear shim |
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bobsterfl 
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Joined: Jun/18/2009 Location: Orlando, Fl Status: Offline Points: 261 |
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 Topic: dist gear shimPosted: Mar/13/2018 at 3:05pm |
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Got this answer from RobbMc performance some time ago. He was formerly an engineer at Mallory (I believe) so has some experience with these things.
"The minimum endplay is .010" to allow for expansion of the aluminum housing. Maximum endplay is debated but I like to keep it under .030". When you drill the hole, make sure the hole is lined up with the oil pump drive tang. Use the washer between the gear and the housing but make sure the OD of the washer is no larger then the root diameter of the gear teeth or the washer will rub on the cam gear. I've seen Mallory AMC distributors supplied with the Chevy washer which is too big. If I remember correctly, the AMC washer is 7/8" OD. Be sure you have the washer in place when you drill the shaft." Robb make some good products for AMC's. Check his website at http://www.robbmcperformance.com/ |
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xspiriment
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Joined: Apr/27/2009 Location: New Mexico Status: Offline Points: 379 |
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Posted: Jan/14/2018 at 8:23am |
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Thanks for all of your inputs. There is a end play spec of.010 minimum. i'm going to set it for about .015 that should be good. I had an excess of .030 with a very worn shim so that's why I shimming it a little tighter. Thanks again.
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Lyle
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Joined: Jul/17/2014 Location: None Status: Offline Points: 772 |
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Posted: Jan/13/2018 at 7:31am |
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The distributor gear will get "eaten up" if you shim the distributor shaft down so when hot there is no clearance with the oil pump shaft. The distributor gear is the weak link.
There is suppose to be at least 0.010" between the top of the oil pump shaft and the distributor shaft were they will interfere, not the engagement, to allow for thermal expansion. If the distributor end play is too large the timing will "float" excessively. Picture the shaft riding up or down a slope and how the rotor will move - it has to rotate as it moves up or down.
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Rebel327
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Joined: Jan/26/2014 Location: Toledo Ohio Status: Offline Points: 358 |
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Posted: Jan/12/2018 at 9:24pm |
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TSM has spec.
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billd
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Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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Posted: Jan/12/2018 at 7:50pm |
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That's about where I go with 'em. Never a problem.
I use regular machine shims. |
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jcisworthy
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Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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Posted: Jan/12/2018 at 7:37pm |
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I shoot for .010 end play
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Specializing in dyno services, engine building, and cylinder head porting
rbjracing.com Phone Number 518-915-3203 |
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billd
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Posted: Jan/12/2018 at 7:20pm |
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But since all that is happening is removing some of the play, there's no reason it should "eat gears".
If the range was up .010 and down .010 and all you do is narrow that, you aren't introducing any new part of the gear to the other gear. Now if you made the play LARGER it could move into unworn areas but removing play unless you made it tight as things heated up there's no reason. No angle is changing - it's moving up and down within a range as it is, you are simply narrowing that range. My bet - unless there was no play left when it got hot,, it wasn't the act of removing excess play - it was something that was going to happen anyway, but was being blamed on taking out some of the play.
The gears were already touching in that range, the range just got a bit smaller. |
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Bill F
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Joined: Feb/21/2017 Location: Maryland Status: Offline Points: 244 |
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Posted: Jan/12/2018 at 6:54pm |
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Remember they are bevel gears designed to run at angles to each other. The forces when running should set the gear where it needs to be. I'd be careful changing the shims.
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Boris Badanov
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Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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Posted: Jan/12/2018 at 6:24pm |
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How much play do you have?
You need a bit to allow in oil. |
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Gremlin Dreams
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billd
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Posted: Jan/12/2018 at 5:18pm |
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I remove some of the end-play and have never had an issue, however, there are other variables at play here - would they have been eaten anyway? It is possible it wasn't your shimming out some of the end play that did it? Less end play, as long as you don't take out so much thermal changes cause a bind, should cause no issues - unless of course you shift worn areas into unworn areas and so on...... perhaps the gears would have gone south anyway.
Are you SURE it was the removal of some of the end play that did it? |
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