Distributor vacuum advance
Thread Starter
Advanced
Joined: Aug 2006
Posts: 53
Likes: 0
From: Stuart FL
Distributor vacuum advance
My mechanic has advised me that my vacuum advance for my 76 distributor is shot. When I need parts-I try to replace them with nos. I am finding 2 GM part numbers for that year( 1973482 and 1973517).Vendors have not been able to tell me the differance. My vette is L48 automatic. Anyone know which one I might need w/o taking it out first. I have tried to find p/n but can't see one.
Thanks!
Thanks!
Tech Contributor
Joined: Aug 1999
Posts: 14,384
Likes: 6,408
From: At my Bar drinking and wrenching in Lafayette Colorado
Select and use a vacuum advance that is correctly tailored to your engine using the info in my Vacuum Advance tech paper - this discusses the topic in detail and has all parts numbers needed with their specs. You can e-mail me for a copy at
V8FastCars@msn.com
Lars
V8FastCars@msn.com
Lars
Race Director
Joined: Oct 2000
Posts: 12,703
Likes: 3,153
From: Shamong, NJ
I have 3 1976 Corvette parts books (9-75, 1-76 & 6-76) and in all 3 only one vacuum advance is listed; 1973508 for use with "Calif emission, special high performance" (L-82s).
My 78 parts book lists 4, though. The first is the 1973508 (which is the same one as in the 76 book) for "CA L-82s", the second is 1973482 listed for "automatic trans except CA L-82s" (I think this means federal emission L-48 or L-82s with an auto). The third one is 1973577 listed for "L-82 OR Calif" (I'm guessing this means federal L-82 4 speeds or CA L-48s) and the final one is 1973517 listed for "76 except CA L-82s" which I'd have to say was for federal L-48 4 speeds.
I know this is a little hard to follow. I wrote it and I'm having a hard time following it.
Unfortunetly, the Chevy parts book isn't always all that clear, and this is one of those times.
Unless your car has Calif emissions, I think you need either the 1973482 if you have an automatic, 1973577 with an L-82 4 speed or the 1973517 with an L-48 4 speed. Like I said, I think!!!!!!!!!!
The part number should only be the last 3 digits (ie: 517, 482, etc.) and will be stamped in the flange between the vacuum canister and the stem that goes into the distributer.
My 78 parts book lists 4, though. The first is the 1973508 (which is the same one as in the 76 book) for "CA L-82s", the second is 1973482 listed for "automatic trans except CA L-82s" (I think this means federal emission L-48 or L-82s with an auto). The third one is 1973577 listed for "L-82 OR Calif" (I'm guessing this means federal L-82 4 speeds or CA L-48s) and the final one is 1973517 listed for "76 except CA L-82s" which I'd have to say was for federal L-48 4 speeds.
I know this is a little hard to follow. I wrote it and I'm having a hard time following it.
Unfortunetly, the Chevy parts book isn't always all that clear, and this is one of those times. Unless your car has Calif emissions, I think you need either the 1973482 if you have an automatic, 1973577 with an L-82 4 speed or the 1973517 with an L-48 4 speed. Like I said, I think!!!!!!!!!!
The part number should only be the last 3 digits (ie: 517, 482, etc.) and will be stamped in the flange between the vacuum canister and the stem that goes into the distributer.
