Hello everybody,
Since I'm still "young" and where i have worked at my jobs there was only late model vehicles so unfortunately i get no practice on classic mechanical systems found on classics.

So my dilemma is.....i scrapped all the emissions vacuum routing underhood so i now am only running distrubtor vacuum advance to carb and brake booster and transmission vacuum line. The thermal valves are deleted.
Undecided on the EGR valve.

I found that my distributor have two vacuum cans. From what it looks like to me is that one is for advance and other is for retarding time correct?

I left the (i believe it was retarded side ) unhooked. It runs fine i hope not too lean or rich for obvious reasons.

I bought an NEW distrubtor for 50 from skip white performance. It has only one vacuum can.

So my question is......can i pull out the old distrubtor and expect to be able to drop the new one in at same mark as old distrubtor was at. (Location of vacuum can and rotor pointed to a fixed location)
Would it be reasonable to expect it to fire up and run without changing anything for the dual vacuum cans on the old distrubtor?

Sorry for being long winded but thanks for reading
Brandon

 

What vehicle are you working on?

 

1980 olds ninety eight regency with 307 olds

 

Why would that have a dual vac. canister?

When you drop in the new, how do you intend to ensure that the timing remains EXACTLY the same, or adjust it to the optimal setting?

Do you understand not only how the spark is made at the right time and delivered, but the engineering reasons why the vacuum and centrifugal advance systems are used? How to alter their range of motion to suit your engine's needs?

Evidently precise spark timing is crucial and affects many things like economy, overheating, performance, detonation, etc.

 

I do not have any idea why the car has dual vac canisters on the distributor. I'm not an whiz i admit but i understand that vacuum advance is for at idle and low power requirements and some people prefer ported vs full manifold vacuum. The mechanical advance is for revving up if i understand. while engine is under load. The timing goes back to zero to spark the mixture at "normal" time where advance would spark the mixture early.
I have a basic timing light and i have used that on TBI systems to set the engine at zero timing with the distrubtor wire unhooked. So i plan to buy an advance timing light if that's needed and i think the initial timing should be 4-8 degrees with vacuum canister plugged up then set the advance timing light to 28-36 degrees and see where engine likes it. Correct me if I'm wrong. I'm here to learn about this.

 

OK, having a timing light and being aware of how to set the timing is half the battle.

Any chance you can show a photo of this dual canister vacuum advance thing?


"can i pull out the old distrubtor and expect to be able to drop the new one in at same mark as old distrubtor was at. (Location of vacuum can and rotor pointed to a fixed location)"
===
Pretty much that easy, yes.
I would set the engine to TDC, then move it back and forth by hand until the magnetic teeth in the dist'r which trigger the spark are exactly lined up, then put in the other dist'r with the rotor and housing in the same place that the old one used, and then carefully align its trigger teeth. At that point, it should be exactly the same, within a coulple crank degrees.

 

Unless you have some oddball emissions controls, the stock distributor for a 1980 Olds 307 did NOT have a "dual vacuum canister". Can you post a photo?

 

That's what i was thinking that this car is an oddball because i found other odd things like for example an th400 behind the 307. I think they was supposed to come with th350.
But anyways back to the distrubtor.
I tried to take best photographs i can for everybody here to see.

If you need any other photo or anything just ask.

Brandon

 

The vacuum advance can bolted directly to the distributor is the only "vacuum cannister" associated with the distributor. The thing bolted to the intake is NOT part of the distributor. It's a vacuum switch of some sort, as the other thing coming out of it is a wire. This distributor uses the oddball five-pin HEI module that was used only in 1980 (and maybe 81). The non-computerized 307 was definitely a transition year engine, but there is still only ONE vacuum can on the distributor.

 

What's that part bolted on the intake acting as switch for?

Would i expect any issues swapping in this? http://www.skipwhiteperformance.com/...px?Item=6503-B

 

The five pin HEI module has a built-in spark retard feature. When the fifth pin (the one connected to that vacuum switch on the intake) is grounded, the spark is retarded five degrees. This was done for emissions control purposes. The aftermarket HEI is a four pin unit. It will not plug in exactly. You'll need to bypass whatever system provides that timing retard signal. Start with the 1980 Chassis Service Manual and read the appropriate section to understand what this part does before removing it.

 

Thanks very much for clarifying that up for me, Joe!
I hope my manual comes in today so i can look at it. I already ordered the chassis and body manuals from amazon.

 

The extra vacuum thingy is probably a switch to supply a signal to the dist'r's 5th pin depending on engine vacuum.


Would i expect any issues swapping in this? http://www.skipwhiteperformance.com/...px?Item=6503-B

My faorite part:

"WE VE BEEN ASKED MANY TIM"

 

Well, I'm sure they have!

- Eric