Gents, I recently had a 57 pontiac fall in my lap. Not a bad little car but it's had a 68 Chevelle SBC (alternator and all) transplanted in where the stock 283 should be. from what I've been reading a Oshawa built 57 Pontiac was built on a 57 Chev platform and the suspention and mechanical parts were interchangeable. My question is since my underhood and under dash/hood wiring look like a birds nest would it be reasonable to assume that a repro chevy wiring harness suited for an alternator SBC would work in my Pontiac?
your thoughts...
seventy2plus2 said
Aug 20, 2012
I'd say maybe, but won't go any further than that. Keep in mind the harness is for many things (horn relay, etc) and whether they're positioned in the same place on a 57 Chev vs 57 Pontiac is doubtful. I'd say get repro 57 Pontiac harness, then make the modification for the alternator swap. I believe there are a couple types of alternators, internally regulated and externally regulated, likely dependent on the vintage.
Bad57Pontiac said
Aug 20, 2012
Who is making a repro Pontiac harness?
B-52 said
Aug 20, 2012
You can contact painlesswiring.com and they can custom make you a wire harness for your whole car. Just give them all the info about your car. Unless you know a good auto electrician in your area that can splice two wire harnesses together properly and make it look factory (or you can delivery your car to me in Winnipeg and I can make it happen I love fixing work of others)
seventy2plus2 said
Aug 20, 2012
Bad57Pontiac wrote:
Who is making a repro Pontiac harness?
Try Ames Performance Engineering - they're in New Hampshire.
seventy2plus2 said
Aug 20, 2012
www.amesperf.com from page 123 of the Ames Full Size Pontiac Catalog.
I am going to assume that your 57 is very much like my 56 (except for obvious differences such as heater/blower, dash, fenders, etc.) - the chassis is 100% Chevrolet including everything under the hood - down to regulator and horn relay locations.
Under the dash, since the gauges (and there is a big difference in that the Pontiac had an ammeter and oil pressure gauge, Chevy only had idiot lights) and their locations are Pontiac, the wiring is basically Pontiac. Under the hood, you car's wiring is basically Chevy. So neither harness will work correctly. (Those gauge differences are part of why, since the ammeter and oil pressure wiring extends under the hood as well as under the dash.)
To further compund the problem:
1. If your car has been switched from original generator/regulator to alternator, there are significant wiring differences there (you can do research on this topic, I will not repeat it here)
2. Some of the Canadian Pontiac wiring is NEITHER Chevy or Pontiac - for example, here is what I found for my 1956 light switch:
I have both Pontiac and Chevrolet wiring diagrams and depending on what I need to figure out, I have to look at both and decipher what is correct - and as you can see from the light switch (which is physically the same as American Pontiac) sometimes the wiring is a blend of both.
Sorry there is no easy answer - consider it part of the challenge of owning something unique, eh?
Dave
-- Edited by davelacourse on Tuesday 21st of August 2012 04:12:16 PM
4SPEED427 said
Aug 21, 2012
I would say a Chevy harness would be way closer than a American Pontiac . I have seen both and the American is way different the horn placement and every thing is the same as Chevy.
willismcbillio said
Aug 21, 2012
Painless wiring harnesses are exactly that. I picked up the 18-point 55-57 chevy harness and had no issues with it except for some problems with their headlight connectors. Attaching the ammeter was in their documentation but I opted not to wire mine in as I will be putting in an alternator and the higher amps would burn it out.
I redid the wiring in my 56 outside in January in a Saskatchewan winter and the whole process took about 8 hours. The Painless documentation lets you know the start and endpoint of wires, with start and endpoints stamped right onto the wires themselves as well. They have alternate wiring if you're running your own ballast resistor or HEI distributor, electric fan, integrated brake lights or separate. And they provide enough wiring so that if you want to mount your fusebox in your trunk, you could.
Now the issue I had with the headlight connectors is that they supply new headlight connectors that are about an inch and a half long, while the originals are about 3/4 inch. The new ones dont fit in behind the headlights without a lot of pressure on them, so I kept the old ones. There are going to be differences between the manual and what is actually under the dash, but its not hard to figure out a way to wire in the instrument lights or how to wire in the horn. Oh, and the painless kit has a new horn relay built into the fuse box.
The 18-point is really overkill and wouldn't be useful unless you plan on power doors, windows, trunk light, etc. the 12-point is a-okay.
My question is since my underhood and under dash/hood wiring look like a birds nest would it be reasonable to assume that a repro chevy wiring harness suited for an alternator SBC would work in my Pontiac?
your thoughts...
I'd say maybe, but won't go any further than that. Keep in mind the harness is for many things (horn relay, etc) and whether they're positioned in the same place on a 57 Chev vs 57 Pontiac is doubtful. I'd say get repro 57 Pontiac harness, then make the modification for the alternator swap. I believe there are a couple types of alternators, internally regulated and externally regulated, likely dependent on the vintage.
Try Ames Performance Engineering - they're in New Hampshire.
www.amesperf.com from page 123 of the Ames Full Size Pontiac Catalog.
PM02420
1957 Dash & Engine Compt. Harness........... 506.00/ea.
I am going to assume that your 57 is very much like my 56 (except for obvious differences such as heater/blower, dash, fenders, etc.) - the chassis is 100% Chevrolet including everything under the hood - down to regulator and horn relay locations.
Under the dash, since the gauges (and there is a big difference in that the Pontiac had an ammeter and oil pressure gauge, Chevy only had idiot lights) and their locations are Pontiac, the wiring is basically Pontiac. Under the hood, you car's wiring is basically Chevy. So neither harness will work correctly. (Those gauge differences are part of why, since the ammeter and oil pressure wiring extends under the hood as well as under the dash.)
To further compund the problem:
1. If your car has been switched from original generator/regulator to alternator, there are significant wiring differences there (you can do research on this topic, I will not repeat it here)
2. Some of the Canadian Pontiac wiring is NEITHER Chevy or Pontiac - for example, here is what I found for my 1956 light switch:
I have both Pontiac and Chevrolet wiring diagrams and depending on what I need to figure out, I have to look at both and decipher what is correct - and as you can see from the light switch (which is physically the same as American Pontiac) sometimes the wiring is a blend of both.
Sorry there is no easy answer - consider it part of the challenge of owning something unique, eh?
Dave
-- Edited by davelacourse on Tuesday 21st of August 2012 04:12:16 PM
Attaching the ammeter was in their documentation but I opted not to wire mine in as I will be putting in an alternator and the higher amps would burn it out.
I redid the wiring in my 56 outside in January in a Saskatchewan winter and the whole process took about 8 hours. The Painless documentation lets you know the start and endpoint of wires, with start and endpoints stamped right onto the wires themselves as well. They have alternate wiring if you're running your own ballast resistor or HEI distributor, electric fan, integrated brake lights or separate. And they provide enough wiring so that if you want to mount your fusebox in your trunk, you could.
Now the issue I had with the headlight connectors is that they supply new headlight connectors that are about an inch and a half long, while the originals are about 3/4 inch. The new ones dont fit in behind the headlights without a lot of pressure on them, so I kept the old ones. There are going to be differences between the manual and what is actually under the dash, but its not hard to figure out a way to wire in the instrument lights or how to wire in the horn. Oh, and the painless kit has a new horn relay built into the fuse box.
The 18-point is really overkill and wouldn't be useful unless you plan on power doors, windows, trunk light, etc. the 12-point is a-okay.
http://www.painlesswiring.com/Manuals/20106.pdf