Ignition: Vacuum advance identification & replacement

[cochranjd]

Hey all - think my vacuum advance has gone bad. Car is a 1961 289 Hawk. Tested a few different ways -

1. Hooked the advance up to manifold vacuum and started the car. Disconnected the hose from the carb and it had no impact on the idle/rpms
2. Actually sucking on the end of those had no impact on the engine rpms
3. Took the cap off and sucked on the end of the hose and it didn't move the arm at all

When trying #3, there is no real resistance - I can hear air coming into the hose from the distributor (hose is good). I'm assuming the diaphragm is busted??

Anyhow, I believe I have a prestolite distrubutor and have pertronix installed - I was going to post some pictures of the vacuum unit and see if anyone could help me identify a replacement.

Here are some pics:



Disregrad the electrical tape on the fitting - that was just to make sure there was no leak where the hose connects.

Would love to buy from a vendor, but not sure which part this is (looking at this page, for instance - https://mystudebaker.com/electric/di...cuum-advances/ )

Also found this from a mopar site, which I believe is the right fit, but for that price, I want to make sure its my best/only option - https://www.tonysparts.com/all-parts...nit-p372008377

Thanks all

[StudeRich]

Hi Josh,

None for '62 to '64 Standard V8 Non-Avanti Prestolite Single Point Distributors are available at that Stude. Vendor and Most others.

The Mopar Units would likely have way different Advance curves for higher Performance, Different Cam Profiles and Larger V8's.

• Your best option is to find one of the Co's that Remanufacture Vacuum Advances.
• Or buy a Used 1953 to 1959 Stude. Early Delco-Non-Window Distributor that your car came with, that New Advances (530673) ARE available for.

Unless you stay with the easily found replacement Points, you would also of course need a Pertroniix Unit for an Early Delco (at least Two Types are available) for that VERY common GM Distributor, Igniter I and Igniter II.

[cochranjd]

Thanks Rich - I have read some good things about Terrill Machine, so I may reach out to them.

Otherwise, I'll look into the early delco idea.

Appreciate it!

[Studebakercenteroforegon]

Last I knew ‘62 - ‘64 Prestolite Vacuum Advance units were available from Studebaker International. 1555505, for single point Prestolites. I have these in my inventory since I am a fan of Prestolite distributors.

[JoeHall]

When testing the VA by sucking the nipple with your mouth (grin), if there's no vacuum when you suck on it, in other words if it's like sucking through a straw, then the diagram is likely ruptured and must be replaced. I say "likely" because you must insure the metal nipple is screwed in tight, and not leaking, and that the larger connector, the nipple screws into, is also tight in the VA body and not leaking. A leak in either of those areas will produce same results as if the diagram is bad.

Looking at one of your pics, it appears the inner spring may be absent in the VA. I say that because the drawbar (for lack of better term) appears to be resting at full advance, when it should be resting at full retard. Hard to know for sure in that one pic, and none of the other pics show that area.

Agree Terrill Machine has been great over the decades. But I have not bought anything from him in about a decade, and I hear it has changed hands. Not sure if that's good or not.

[Bud]

A Chrysler/Prestolite vacuum advance can be used on a Studebaker distributor though in many instances, the amount of advance will have to be limited a bit. Adjusting the advance curve can be done with the distributor on the engine, but the best way is to do the adjustments is by using a distributor machine if you can find someone that has a working one. I have in a pinch used mechanics wire to make a collar on the Chrysler advance to limit its travel. Bud

[stude1964]

Antique Auto in TX. rebuilds the advances-check their ad in Hemmings. I picked up one at Hershey, PA. meet and was told that was where it was rebuilt as well as other parts.
Rob in PA.

[r1lark]

I saw a notice somewhere that Dave Thibeault is now rebuilding vacuum advances.

[ndynis]

I saw a notice somewhere that Dave Thibeault is now rebuilding vacuum advances.

I have purchased two vacuum advance units from Dave. He requires that you send the old one to him to be rebuilt if I remember correctly.

[dpson]

In my collection of "stuff" there is a new old replacement stock (NORS) "Poweready" Vacuum Advance unit that is unidentified. The part number on the box is 37-19. I don't know what it fits, but it looks like the unit you have (it may be for MOPAR vehicles). I gave it a "suck" test and it seems to pull well, so the diaphragm appears good. If it's something you want to try the price is $20 plus actual shipping. Photos attached.

[Bud]

dpson, your vacuum advance should work on a Studebaker/Prestolite distributor with minor modifications to the amount of advance. The rate of advance is not a problem as it is controlled by a spring and a few washers. I just checked my stock of original Prestolite parts and they look the same as yours. Bud

[dpson]

It's interesting the "Poweready" unit has the AL (Autolite) brand symbol cast in the diecast base.

[bezhawk]

Pretty much any Prestolite advance V8 unit with the screw in end fittings will work the advance rate is controlled by washers and a spring under the screw in fitting. Change that out with the new one and you should be good to go.

[Bud]

Poweready was the brand name for the now defunct Big A Auto Parts. They most likely bought parts from other suppliers such as Prestolite because it was cheaper than producing their own parts. bezhawk is correct about the rate of advance being controlled by a spring and washers, but the amount of advance can be different between an advance unit meant for a Studebaker engine and one meant for a Chrysler engine. The Chrysler units I've seen usually have a longer stroke on the connecting rod which will cause too much vacuum advance and possible detonation if used with a Studebaker distributor. Bud

[bezhawk]

The advance plate in the distributor is what limits the stroke of the vacuum canister. It can only move so far. It (the breaker plate/advance plate) has limiting stops built into it. The stroke of the canister has nothing to do with it.