Would anybody know the spec for distributor end play ( up and down play in in shaft which is determined by shim between distributor body and drive gear ) for a 1966. If I read the shop manual correctly they call for .002 to .007. That seems extremely tight to me. Mine was real sloppy at .060 so I set it to .021 with the shims I had. Any thoughts ?
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Re: Distributor End Play
Pete my 63-64 shop manual gives the same .002"-.007" end clearance. When I set up the distributor in my 70 it had a lot of play and I used the same information to shim it. No problems and this was done back in the early 80's. -
Re: Distributor End Play
Pete my 63-64 shop manual gives the same .002"-.007" end clearance. When I set up the distributor in my 70 it had a lot of play and I used the same information to shim it. No problems and this was done back in the early 80's.Comment
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Re: Distributor End Play
Excess end play can cause the ignition to break up at high revs. Shimming up the end play to the shop manual spec is part of blueprinting the distributor. Shims were available from GM in .030" and .006" thicknesses to achieve the shop manual spec.
It appears that the FI distributors were shimmed up to the spec, but the non-FI versions were left sloppy, and that's one reason why the ignition would break up at high revs, especially the high revs that SHP engines turn.
DukeComment
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Re: Distributor End Play
Excess end play can cause the ignition to break up at high revs. Shimming up the end play to the shop manual spec is part of blueprinting the distributor. Shims were available from GM in .030" and .006" thicknesses to achieve the shop manual spec.
It appears that the FI distributors were shimmed up to the spec, but the non-FI versions were left sloppy, and that's one reason why the ignition would break up at high revs, especially the high revs that SHP engines turn.
DukeComment
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Re: Distributor End Play
Thanks guys, guess I'll tighten it up a little more . Perhaps that built in slop was a crude attempt at a rev limiter from the factory !Comment
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Re: Distributor End Play
Thanks guys, guess I'll tighten it up a little more . Perhaps that built in slop was a crude attempt at a rev limiter from the factory !Comment
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Re: Distributor End Play
Peter-----
This subject has been discussed on numerous occasions on this board. All that I'll say about it is this:
1) I have several NOS, in-the-GM box distributors which all have the end play set at 0.060";
2) On the engineering drawings for the distributors, GM specifies the end play to be in a range for which 0.060" is right in the middle;
3) If GM had considered a tighter end play important/necessary and/or wanted the end play to be set at some other setting, I do not understand why that specification was not shown on the engineering drawings. In PRODUCTION, I do not understand why it would have been any more difficult/costly to set the end play at, say 0.005", than it would to set it at .060".
4) I do not know, for sure, what reason that GM had for specifying the distributor end play which they did. But, I think that they had a reason.In Appreciation of John HinckleyComment
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Re: Distributor End Play
Peter-----
This subject has been discussed on numerous occasions on this board. All that I'll say about it is this:
1) I have several NOS, in-the-GM box distributors which all have the end play set at 0.060";
2) On the engineering drawings for the distributors, GM specifies the end play to be in a range for which 0.060" is right in the middle;
3) If GM had considered a tighter end play important/necessary and/or wanted the end play to be set at some other setting, I do not understand why that specification was not shown on the engineering drawings. In PRODUCTION, I do not understand why it would have been any more difficult/costly to set the end play at, say 0.005", than it would to set it at .060".
4) I do not know, for sure, what reason that GM had for specifying the distributor end play which they did. But, I think that they had a reason.In Appreciation of John HinckleyComment
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Re: Distributor End Play
Joe,
Your points are well taken. However it is disturbing to find that the distributor is .050 (or more) from the spec listed in the factory shop manual. High RPM spark scatter is one possible side effect but what effect might all of that slapping around have on the tach drive ? So the question remains .060 or .002 to .007 ?Comment
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Re: Distributor End Play
Joe,
Your points are well taken. However it is disturbing to find that the distributor is .050 (or more) from the spec listed in the factory shop manual. High RPM spark scatter is one possible side effect but what effect might all of that slapping around have on the tach drive ? So the question remains .060 or .002 to .007 ?Comment
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Re: Distributor End Play
i also believe that the excess end play is one of the causes if the tach gear drive failure. i always set my end play to .005/.006 and never had a tach drive gear fail. i think the FI distributors were set at this low number because of the drive gears for the FI pump.Comment
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Re: Distributor End Play
i also believe that the excess end play is one of the causes if the tach gear drive failure. i always set my end play to .005/.006 and never had a tach drive gear fail. i think the FI distributors were set at this low number because of the drive gears for the FI pump.Comment
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Here we go again!
As Joe L. mentions, this has been discussed several times. I initiated one of the threads and to the same end result. Until someone comes up with a reason why Joe's in the box NOS units have .060 and the GM manuals call for a whole lot less, most of us are in the dark when rebuilding distributors.
GaryComment
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Here we go again!
As Joe L. mentions, this has been discussed several times. I initiated one of the threads and to the same end result. Until someone comes up with a reason why Joe's in the box NOS units have .060 and the GM manuals call for a whole lot less, most of us are in the dark when rebuilding distributors.
GaryComment
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