stop advance bushing
Melting Slicks
Joined: Jun 2005
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From: North of the Bay California
Le Mans Master
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From: columbus oh
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
The "stop" bushing is just pressed over the stop-pin on the underside of the advance plate. You do have to drive-out the pin in the drive gear, then remove the gear & shim to lift the plate/shaft assembly out. Then use pliers [whatever] to wiggle the stop off the pin. Replace it with the new stop and reassemble it. If the stop is not tight on the pin, you can use a bit of Loctite to hold it or pinch/crimp it on.
[Note that the gear is an uneven number of teeth, so it is important to put an index mark on the gear and the shaft to assemble it the same as it was.
[Note that the gear is an uneven number of teeth, so it is important to put an index mark on the gear and the shaft to assemble it the same as it was.
Thread Starter
Racer
Joined: Mar 2009
Posts: 331
Likes: 1
From: Brooklin Ontario
The "stop" bushing is just pressed over the stop-pin on the underside of the advance plate. You do have to drive-out the pin in the drive gear, then remove the gear & shim to lift the plate/shaft assembly out. Then use pliers [whatever] to wiggle the stop off the pin. Replace it with the new stop and reassemble it. If the stop is not tight on the pin, you can use a bit of Loctite to hold it or pinch/crimp it on.
[Note that the gear is an uneven number of teeth, so it is important to put an index mark on the gear and the shaft to assemble it the same as it was.
[Note that the gear is an uneven number of teeth, so it is important to put an index mark on the gear and the shaft to assemble it the same as it was.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Well, it is a 'press fit'. If it weren't, vibration would shake it off the pin. You will need to 'tap' or press it on. Start easy and work up; you don't want to use any more force than necessary. And support the other side of the plate so that you don't bend anything.
Tech Contributor
Joined: Aug 1999
Posts: 14,365
Likes: 6,345
From: At my Bar drinking and wrenching in Lafayette Colorado
Good job spotting the missing bushing - most people never know it's gone. A missing bushing will cause an advance curve that is waaay too long, producing too much total timing (along with possible detonation, power loss, and engine damage) or not enough initial timing if total is set.
You need to completely disassemble the distributor and pull the mainshaft out. Get Mr. Gasket part number 928G - it has a brass advance stop bushing that is very good. Lay the bushing on its side and give it a light smack with a hammer to make it oval - this will make it fit extremely tight onto your stop pin, which is undersized due to years of light corrosion. If you do not do this, the stop bushing will fall off at high rpm and short out your points. Don't ask me how I know this.
Use a hammer to pound the de-formed stop bushing onto the shaft pin by holding the shaft upside-down on an anvil. You know you have it tight enough if brass shavings come off the bushing when you smack it on.
Put the distributor back together. making sure the "dimple" in the distributor gear is pointing the same direction as the firing tab on the rotor.
Charley (7T1vette) has good and technically accurate comments above.
Lars
...and just my opinion, but throw that PerTronix in the trash and put a good set of points in your unit...
You need to completely disassemble the distributor and pull the mainshaft out. Get Mr. Gasket part number 928G - it has a brass advance stop bushing that is very good. Lay the bushing on its side and give it a light smack with a hammer to make it oval - this will make it fit extremely tight onto your stop pin, which is undersized due to years of light corrosion. If you do not do this, the stop bushing will fall off at high rpm and short out your points. Don't ask me how I know this.
Use a hammer to pound the de-formed stop bushing onto the shaft pin by holding the shaft upside-down on an anvil. You know you have it tight enough if brass shavings come off the bushing when you smack it on.
Put the distributor back together. making sure the "dimple" in the distributor gear is pointing the same direction as the firing tab on the rotor.
Charley (7T1vette) has good and technically accurate comments above.
Lars
...and just my opinion, but throw that PerTronix in the trash and put a good set of points in your unit...
Last edited by lars; Mar 30, 2010 at 09:18 PM.
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Thread Starter
Racer
Joined: Mar 2009
Posts: 331
Likes: 1
From: Brooklin Ontario
Good job spotting the missing bushing - most people never know it's gone. A missing bushing will cause an advance curve that is waaay too long, producing too much total timing (along with possible detonation, power loss, and engine damage) or not enough initial timing if total is set.
You need to completely disassemble the distributor and pull the mainshaft out. Get Mr. Gasket part number 928G - it has a brass advance stop bushing that is very good. Lay the bushing on its side and give it a light smack with a hammer to make it oval - this will make it fit extremely tight onto your stop pin, which is undersized due to years of light corrosion. If you do not do this, the stop bushing will fall off at high rpm and short out your points. Don't ask me how I know this.
Use a hammer to pound the de-formed stop bushing onto the shaft pin by holding the shaft upside-down on an anvil. You know you have it tight enough if brass shavings come off the bushing when you smack it on.
Put the distributor back together. making sure the "dimple" in the distributor gear is pointing the same direction as the firing tab on the rotor.
Charley (7T1vette) has good and technically accurate comments above.
Lars
...and just my opinion, but throw that PerTronix in the trash and put a good set of points in your unit...
You need to completely disassemble the distributor and pull the mainshaft out. Get Mr. Gasket part number 928G - it has a brass advance stop bushing that is very good. Lay the bushing on its side and give it a light smack with a hammer to make it oval - this will make it fit extremely tight onto your stop pin, which is undersized due to years of light corrosion. If you do not do this, the stop bushing will fall off at high rpm and short out your points. Don't ask me how I know this.
Use a hammer to pound the de-formed stop bushing onto the shaft pin by holding the shaft upside-down on an anvil. You know you have it tight enough if brass shavings come off the bushing when you smack it on.
Put the distributor back together. making sure the "dimple" in the distributor gear is pointing the same direction as the firing tab on the rotor.
Charley (7T1vette) has good and technically accurate comments above.
Lars
...and just my opinion, but throw that PerTronix in the trash and put a good set of points in your unit...
So I take it I remove the inner shaft so I can properly press on the bushing. In diagrams I see a retaining clip, is this not required?
Lars, as per your e-mail I will do a complete restore of the unit back to points after I iron out this issue. I tend to compound my screw ups attempting too many changes at a time. I went to petronix as I have no previous experience with points. I'll keep the petronix as an on-board hot spare.
Thanks Guys
Later, Rog.
Tech Contributor
Joined: Aug 1999
Posts: 14,365
Likes: 6,345
From: At my Bar drinking and wrenching in Lafayette Colorado
The retaining clip was used by the factory to keep the stock rubber sleeve on the pin - the rubber tended to "relax" over time and fall off (as yours has). The brass bushing, once given the "calibrated smack," will not fall off, so the clip is not needed.
Lars
Lars
Intermediate
Joined: Sep 2018
Posts: 36
Likes: 0
From: Venice - Italy
Good job spotting the missing bushing - most people never know it's gone. A missing bushing will cause an advance curve that is waaay too long, producing too much total timing (along with possible detonation, power loss, and engine damage) or not enough initial timing if total is set.
You need to completely disassemble the distributor and pull the mainshaft out. Get Mr. Gasket part number 928G - it has a brass advance stop bushing that is very good. Lay the bushing on its side and give it a light smack with a hammer to make it oval - this will make it fit extremely tight onto your stop pin, which is undersized due to years of light corrosion. If you do not do this, the stop bushing will fall off at high rpm and short out your points. Don't ask me how I know this.
Use a hammer to pound the de-formed stop bushing onto the shaft pin by holding the shaft upside-down on an anvil. You know you have it tight enough if brass shavings come off the bushing when you smack it on.
Put the distributor back together. making sure the "dimple" in the distributor gear is pointing the same direction as the firing tab on the rotor.
Charley (7T1vette) has good and technically accurate comments above.
Lars
...and just my opinion, but throw that PerTronix in the trash and put a good set of points in your unit...
You need to completely disassemble the distributor and pull the mainshaft out. Get Mr. Gasket part number 928G - it has a brass advance stop bushing that is very good. Lay the bushing on its side and give it a light smack with a hammer to make it oval - this will make it fit extremely tight onto your stop pin, which is undersized due to years of light corrosion. If you do not do this, the stop bushing will fall off at high rpm and short out your points. Don't ask me how I know this.
Use a hammer to pound the de-formed stop bushing onto the shaft pin by holding the shaft upside-down on an anvil. You know you have it tight enough if brass shavings come off the bushing when you smack it on.
Put the distributor back together. making sure the "dimple" in the distributor gear is pointing the same direction as the firing tab on the rotor.
Charley (7T1vette) has good and technically accurate comments above.
Lars
...and just my opinion, but throw that PerTronix in the trash and put a good set of points in your unit...
Thanks a lot!
Filippo
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Hi and Welcome.
[QUOTE=Masfel74;1606237097]Hello to everybody, I found this old post. I'm working on my '69 L36 Corvette's distributor. It seems ok but it doesn't give more than 15 degrees in mechanical advance (it's really the maximum, I also tried with very soft springs). I read that it should be 26 degrees. If I don't pass the 36 deegres in total advance can I remove the stop advance bushing for have some more degree or it's better to have something around the pin?
Next time start a new post.
Next time start a new post.
Last edited by Peterbuilt; Feb 5, 2023 at 04:28 PM.
Le Mans Master
Joined: Aug 2006
Posts: 7,413
Likes: 1,552
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
