What is the vaccum advance, and what does a new one cost?

[Zack1978]

Hey everyone,
I had my 87 fj60 at the mechanic this past week for some work, including setting the timing. The truck was pinging and there was a slight backfire at idle. So when he checked the truck out, he found that the vaccum advance was/is bad. What is the vacc advance? How does it work? Do I have to replace the entire dist to fix the problem? What is the cost for a new vacc advance? How does this part effect the timing?


Thank you,
Zack

 

[beaufort-fj60]

it's the round thing on the side of the dist. not sure on the other questions

 

[60wag]

On FJ60s, its a pair of vacuum diaphrams mouted on the distributor. When vac is applied, the diaphram rotates the guts of the dizzy a bit to advance the timing. One diaphram is a high altitude advance. The other advanced the timing for normal driving. I believe the pair are available from Toyota as a replacement part - not sure what the cost is. If you regularly stay below 4000ft or above 400ft, you can live with one bad diaphram. The outer diaphram is the high altitude advance, (I think) it adds about 7 deg of advance above 4000ft. If that one is leaking, just set the timing to compensate for it and plug the hose. If the inner diaphram is leaking (I think this one does about 10 deg of advance) Move the inner hose to the out diaphram and set the timing as if the high alt is broken. Try CruiserDan to find out the $ to replace the whole assembly. I like to have everything functional but the cost may drive the descision.

 

[Heartworm]

Distributor

I would encourage you to do what is needed to avoid pinging and predetonation. I recently picked up a nice FJ60 for $250 because there was a hole in the #4 piston which I was told was due to predetonation (timing problem perhaps). 60WAG is right that you can run off one vacuum diaphragm; that is the way the de-smogged versions run. I recall the double canister runs about $110 but don't quote me. A used distributor from Cruiserparts.net cost about $75. The one I got worked but the canister was really rusty (northeast salt on roads) and I am fearful that it will start leaking (hasn't yet).
Jim C. does distributors for $100 plus parts. Talk to him. 740-862-2604. Good luck!

 

[Pluton]

Vac advance assembly can be got for about $110; Whole new dist for about $375; Failed vac advance isn't the only thing that can cause pinging, though. Make sure your vac adv is bad by attaching a clean piece of vac hose to the two "biscuits" on the dist(one at a time) and sucking on the hose...you should be able to see the parts inside the dist move/rotate...the diaphragms should "hold air"... if there's no resistance, the vac adv diaphragms(s) are bad.

 

[Zack1978]

Vac advance assembly can be got for about $110; Whole new dist for about $375; Failed vac advance isn't the only thing that can cause pinging, though. Make sure your vac adv is bad by attaching a clean piece of vac hose to the two "biscuits" on the dist(one at a time) and sucking on the hose...you should be able to see the parts inside the dist move/rotate...the diaphragms should "hold air"... if there's no resistance, the vac adv diaphragms(s) are bad.

So if I was to step up and buy a new dist, I would get all the vac advance parts with it?

Zack

 

[FJ40Jim]

Yes, a new distributor is complete w/ vac advance canister.

 

[NocalFJ60]

Another option is the HEI distributor.

https://forum.ih8mud.com/showthread.php?t=64139

 

[NocalFJ60]

Yes, a new distributor is complete w/ vac advance canister.

Jim,

So the HEI distributors cruve is different from the stock toyota ones? I like the idea of the HEI since it is not effected by water as much as the stock dizzy. But then again you can put silcone on the stock cap to seal it better.Also the HEI would not wear out like the rotor or cap in a stock one.

 

[60wag]

Are the stock ones affected by water? I've never had a problem, but I haven't taken my Cruiser swimming lately.

 

[NocalFJ60]

Are the stock ones affected by water? I've never had a problem, but I haven't taken my Cruiser swimming lately.

There is a o-ring but if it is old and water splashs up in there can be a pain. If you haven't changed it, next time you change the dizzy cap grab a o-ring too.

 

[Zack1978]

Well I called Jim C today, and based on the fact that my truck is bone stock with all the smog stuff, I will just keep my stock dizzy and get the new vacc advance.

Zack

 

[FJ40Jim]

Jim,
So the HEI distributors cruve is different from the stock toyota ones?

Yes, there is a strange curve in a stock 79-87 distributor that meshes w/ the flow pattern of the EGR system.

I like the idea of the HEI since it is not effected by water as much as the stock dizzy.

You're baiting me, aren't you. Sadly, it is very easy.

Have you seen a truck idling in a river w/ an HEI distributor underwater?
No, of course not. HEI is nowhere near waterproof. It is not designed to be waterproof. The cap just sits on the distributor body, held down by some little spring thingys, no provision for sealing. The vac canister slipps into a window in the side of the distributor w/ no seal. The cost accountants who do the engineering at Delco did not have "deep water fording capability" on the list of desired charcteristics.
OTOH, the Cruiser system is waterproof and more heat resistant, but far more expensive.

But then again you can put silcone on the stock cap to seal it better.

Unnecessary and redundant on a FJ60 distributor.

Also the HEI would not wear out like the rotor or cap in a stock one.

GM HEi parts suffer a higher failure rate because: a. they are not hermetically sealed; b. all the electrics are crammed into a small space, leading to heat failures; c. they are cheap; d. all of the above.

 

[NocalFJ60]

Yes, there is a strange curve in a stock 79-87 distributor that meshes w/ the flow pattern of the EGR system.

I like to stay stock so even more reason too now.New caps and rotor's are cheap.

Thanks Jim