Distributor Disassembly - 72 LT-1

[Dan A.]

I'm trying to change out the vacuum advance mechanism and have run into a problem. The prior owner had the distributor rebuilt and in the process the slot in the vacuum advance was brazed in an effort to limit the amount of advance, which would have been fine but he went overboard and it was advancing less than 6 degrees. I tried to advance the distributor plate using a Mighty Vac but due to the limited advance the place won't move enough to get the front screw out. The only option I see is to disassemble the distributor and remove the plate. I have disassembled distributors before but have never removed the plate. How does if come out?
Thanks.

[Joe L.]

Re: Distributor Disassembly - 72 LT-1

I'm trying to change out the vacuum advance mechanism and have run into a problem. The prior owner had the distributor rebuilt and in the process the slot in the vacuum advance was brazed in an effort to limit the amount of advance, which would have been fine but he went overboard and it was advancing less than 6 degrees. I tried to advance the distributor plate using a Mighty Vac but due to the limited advance the place won't move enough to get the front screw out. The only option I see is to disassemble the distributor and remove the plate. I have disassembled distributors before but have never removed the plate. How does if come out?
Thanks.

Dan-------


It's pretty simple. After removing the distributor shaft and cam, the plate can be removed simply by removing a small spring clip that is affixed to the top of the upper distributor bushing. The spring clip was GM #1932024 but it's discontinued. However, you can probably re-use your original clip.

[Dan A.]

Re: Distributor Disassembly - 72 LT-1

Joe,

Thanks for the reply. I see the clip you are talking about - it was hidden by the grease.

[Duke W.]

Re: Distributor Disassembly - 72 LT-1

Since you have to disassemble you might as well overhaul. It doesn't take long. After the plate is out carefully remove the plastic seal below the breaker plate and clean and regrease the upper bushing grease well. Clean and reoil the felt washer, too. If you are converting to full time advance, use a B28 VAC. Get a shim kit and shim up the end play to two to seven thou, and use the high tension breaker arm points.

[Dan A.]

Re: Distributor Disassembly - 72 LT-1

Thanks, Duke, that is the plan. One question, though. Somewhere along the road the cam has been changed to a hydraulic one of unknown specifications. Everything else is original as far as I can tell. It shows 15" vacuum at 900 RPM. I am running full time advance. That being the case which VAC would you recommend?

[Duke W.]

Re: Distributor Disassembly - 72 LT-1

The installed cam has less overlap than the LT-1 cam, which has typical idle behavior of 12" @ 900. Given 15" @ 900 the 12" B26 VAC meets the Two-Inch Rule. You could probably idle it a little lower, down to 14" or a little lower. The NAPA part number is VC1765, and any other parts store can cross reference this to whatever brand they carry; and it's very likely that all are made by Standard Motor Products - same part, just a different box. Make sure whatever you buy has "B26" stamped on the bracket. It's also a good idea to test it with a vacuum pump before you leave the store. The link should start to pull at about 6" Hg and be at the limit at about 12".

[Dan A.]

Re: Distributor Disassembly - 72 LT-1

Thanks for the recommendation.

[Frank C.]

Re: Distributor Disassembly - 72 LT-1

I'm trying to remove the breaker plate on my 1111063 distributor. As you can see from the photo I haven't figured out how to do it. Can you tell me how to get this thing apart? Thank you. Frank Condron, Edna, Texas. 100_0939.jpg

Dan-------


It's pretty simple. After removing the distributor shaft and cam, the plate can be removed simply by removing a small spring clip that is affixed to the top of the upper distributor bushing. The spring clip was GM #1932024 but it's discontinued. However, you can probably re-use your original clip.

[Larry M.]

Re: Distributor Disassembly - 72 LT-1

I'm trying to remove the breaker plate on my 1111063 distributor. As you can see from the photo I haven't figured out how to do it. Can you tell me how to get this thing apart? Thank you. Frank Condron, Edna, Texas. [ATTACH=CONFIG]101809[/ATTACH]

There is a very very thin snap ring at the top center of this plate.....around the upper brass/bronze bushing. Look for it and remove it. Then everything else comes out easy.

During my first time at this, I also missed this and wondered why I could not remove the base plate.

Larry

[Frank C.]

Re: Distributor Disassembly - 72 LT-1

Thank you. I'll try again. Frank

[Dan A.]

Re: Distributor Disassembly - 72 LT-1

I had the same issue - see post #2 above. It was simple once Joe pointed me in the right direction.

[Duke W.]

Re: Distributor Disassembly - 72 LT-1

It's a very thin "wavy" snap ring. Use a small tool like a dental curette to carefully hook an end and remove it. If you are careful there's no problem reusing it, but be careful not to damage or loose it.

The 1963 Corvette Shop Manual and '66-up Chassis Overhaul Manuals have an IPB and the disassembly/assembly procedure so you can see the little ring.

I also recommend you search for a 2012 thread started by me - "L-79 blueprint overhaul" for tips on overhauling a single point distributor. You should also be able to reuse the upper bushing grease well seal (It's no longer available) and maybe the oil saturated felt washer, but it is available. And be sure that upon assembly you index the dimple in the gear pointing the same direction as the rotor tip. That instruction is NOT in any service literature I have even seen and has caused no end of problems to guys for DECADES.

You should have whatever manual applies to your year Corvette if you want to overhaul any component like a distributor, starter motor. alternator, steering gear... etc. The 1963 Corvette Shop manual has all service operations, like removing/installing the distributor AND the overhaul procedures for all components. Beginning is 1966 component service and overhaul procedures require both the Chassis Service Manual AND Chassis Overhaul Manual.

Duke

[Frank C.]

Re: Distributor Disassembly - 72 LT-1

Thanks to all of you for responding. I've not yet been successful in finding the snap ring but there has to be one somewhere. There's none visible and no relative movement that exposes or allows room for a clip. I will get a 1963 Covette manual and thanks Duke for the tip on reassembly that's not in the manual. I've looked in vain in the 1962 Corvette and the 1964 Chevrolet manuals that I refer to daily.
When I bought my 1957 in 1973 the fellow I bought it from (I think raced it) had removed the FI unit and the Duntov cam and the solid lifters but he gave me all the original parts. He was running two four barrels with hydraulic lifters, god knows what for a cam and this 1964 distributor. When I replaced the FI and tuned it with a manometer set up the car ran perfectly; cold starts, hot starts, no stumbles, just great. So that's why I have a 1957 engine with a 1964 distributor. But it ran great and I'm sticking with that on my ground up restoration. Thanks again Larry Dan and Duke. Frank Condron, Edna, Texas

[Larry M.]

Re: Distributor Disassembly - 72 LT-1

Thanks to all of you for responding. I've not yet been successful in finding the snap ring but there has to be one somewhere. There's none visible and no relative movement that exposes or allows room for a clip. I will get a 1963 Covette manual and thanks Duke for the tip on reassembly that's not in the manual. I've looked in vain in the 1962 Corvette and the 1964 Chevrolet manuals that I refer to daily.
When I bought my 1957 in 1973 the fellow I bought it from (I think raced it) had removed the FI unit and the Duntov cam and the solid lifters but he gave me all the original parts. He was running two four barrels with hydraulic lifters, god knows what for a cam and this 1964 distributor. When I replaced the FI and tuned it with a manometer set up the car ran perfectly; cold starts, hot starts, no stumbles, just great. So that's why I have a 1957 engine with a 1964 distributor. But it ran great and I'm sticking with that on my ground up restoration. Thanks again Larry Dan and Duke. Frank Condron, Edna, Texas

Frank:

See Page 4 of this PDF attachment.

Distributor Reconditioning - Joe Fisher Dis-assembly and assembly-final copy.pdf

[Frank C.]

Re: Distributor Disassembly - 72 LT-1

Thanks again. I did consult my 1963 Corvette Service Manual and saw what I needed to see but the Joe Fisher PDF was/is outstanding.