Leaking Distributor Vacuum Advance Canister? (1 Viewer)

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Joined
Jan 17, 2018
Threads
3
Messages
11
Location
CA
Hi.
I just completed rebuilding the distributor on the fully-smogged 2f in my 82 FJ40. In doing so, I determined the governor weights were binding up on old sludge/grease that lubricates the weights where they move along the signal rotor.
Other addressed issues:
1. The Dist. also had the classic missing stop-pin bushing; I replaced the missing bushing as well.
2. The ball-bearings in the breaker plate were all gummed up, causing the plate to bind when attempting to be moved by the vacuum advance arm. I cleaned it out with PB Blaster, and it's mostly good; some intermittent small binding can be felt at times, when manually moving the breaker plate. I'm assuming this issue is properly addressed (?)
3. Using my hand vacuum pump and applying vacuum to the advance canister, the vacuum arm does indeed fully retract by the time ~10mmHg is applied. However, I'm expecting that the vacuum should hold, but it doesn't, and the arm will extent back to its resting position unless I continuously feed it vacuum via pumping the hand pump.

Question: is this what is defined as a leaky vacuum canister that is often mentioned in the forums? In my forum research, I have not found a definition for what are the actual symptoms of a leaky canister. FSM does not give any description of bad canister symptoms, rather it only mentions checking if applied vacuum will actuate the arm.

I'll mention that the above rebuild has cured the too-advanced issues in my truck, and has greatly improved low end power and torque, through ~2200 RPM. However, above that RPM range, power and torque are mostlly flat, sprinkled with a few very subtle power stabs as it moves above ~2200RPM; the engine just feels somewhat starved in these higher RPM bands. This truck is the only reference point I have for 2F performance, so I don't know if this is working as intended, or if perhaps is a symptom of a leaky vacuum advance canister.

Other notes: idle advance is set to 10* BTDC (because JimC. always seems in the forums to suggest it), manifold idle is steady at 20mmHg, and it has a fully rebuilt fuel, ignition, and smog system.

Any description of leaky canister is greatly appreciated, as well as any other comments/suggestions.

Thanks!
 
My leaking dissy vacuum advance canister resulted in a large vacuum loss.

My vacuum gauge normally showed 15, but as altitude increased, vacuum continued to drop.

When altitude reached 6k’, my 40 would barely move up even the slightest incline.

I had been looking for a vacuum leak for some time. But, completely overlooked the vacuum advance.

Since the carb port pulls vacuum for the canister, it’s an obvious vacuum leak and sucks away much of the engine power.

I started researching canister rebuild and found people had pried it apart and PlastiDipped the diaphragm and put the canister back together. I didn’t like that fix, I frequent remote areas, alone.

I started looking for a new canister and found nothing.

I didn’t want another old dissy, with an old canister, so I kept looking.

Eventually I came upon several very good testimonials for a DUI (Davis Unified Ignition) dissy/coil/ballast/igniter replacement. Note:early on DUI didn’t have the proper Toyota gear. They fixed that oversight and now sell a Toyota version.

I liked what I read, so I searched MUD classifieds and found someone selling a new Toyota DUI with LiveWire plug wires.

I bought it, installed it and have been very happy with the performance improvement. Note: it’s larger than an oem dissy. I simply rotated it to fit my ‘78. You may need a different side cover.

Granted, part of the improvement is attributable to eliminating the huge vacuum leak.

But, DUI runs hotter, pulling full battery power. Plugs are gapped st .055”, timing set at ~12*BTDC.

I struggled to get to 60mph before... I can cruise at 75mph now. But, I try to stay closer to 65mph.

I see THIS right now and think it’s about what I paid on MUD.

City Racer sells THIS new


TrollHole is another possibility, for new.

Or, you can possibly find a used dissy, with a canister that doesn’t leak... yet.

Or, go the patch route THIS is a good thread. @JohnnyC provides a link to @ducktapeguy ’s thoroughly documented repair.

Good luck!!
 
Thanks for the suggestions and links, Danny.
I'll be checking them out.
I'll say though, that I really want to stay the OEM route, as that is what I've done throughout this truck build.
I know the OEM canister is NLA, and the used route is suboptimal. But I'm thinking (hoping) that sometime in the future, someone will bring to market, OEM-type canister replacements.

If I can get confirmation that what I described is indeed indicative of a leaky canister, that will go a long way in helping me decide what the next step will be.
 
This looks like it would fit. But it does not specify your year. I'm assuming that yours is not a Cali spec 40. However, SOR describes a single part for 8/80 to EFI.
 
Dizzy:
Wow, that's close, but indeed my 40 is a CA spec, and registered in CA......
Your ebay link does at least give me a new avenue to search; i'll poke around and see if there's a listing with a closer fit. Thanks!

The folks at Vacuum Advance Diaphragms & Rare Parts / Advance Diaphragm Options just got back to me, and said they could at a minimum, rebuild my canister, and might even have an exchange unit available, depending on the stamped vacuum casing number. I need to get back to them with that stamp number.
 
I know the OEM canister is NLA, and the used route is suboptimal. But I'm thinking (hoping) that sometime in the future, someone will bring to market, OEM-type canister replacements.
Did you ever find a suitable replacement vacuum advancer? I have a good used NipponDenso dual diaphragm advancer from a late '70s 6-cylinder Toyota that works and holds vacuum. I can modify it similar to how I modified the single diaphragm advancer that went into a recent FJ60 distributor refurbishment. Outwardly, it looks very much like the 2F advancer. I can take some vacuum/displacement readings to compare the advancer to the 2F advancer. PM me if you're interested.

Single-Diaphragm-Distributor-1.jpg


Single-Diaphragm-Distributor-2.jpg
 

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