Vacuum Diaphragm leak

[Ossipon]

I was doing initial tuning of the engine today and was having oddness in response when watching the dwell. The indicators to me was the vacuum advance. When I tested the diaphragm with a vacuum pump gauge, I could tell there was an obvious leak. It would not hold a pull. So now my question.
This is a Vacuum advance only 205G. I feel I have three choices.
Source a replacement, Replace with a SVDA unit, or replace with a 010/009 or similar.
The original 1500S distributor is not on my X low number 1600 engine.
If I replace the diaphragm, is there a specific part #. This question scares me as there seems to be so many different diaphragms out there, and none are cheap. And my concern is whether an old NOS diaphragm might have issues vs a new one.
If I replace the 205G, Would it be better to pursue the original 1500S distributor, or get a "better" replacement.
Or should I just go with a 009/010 Bosch and live with a potential flat spot at times.
Thanks in advance
_________________
Ossipon
VWs in my life:
Air
Type 1 - 59, 62, 63, 71 Super 68 KGhia/ Type 2 - 59 Single Cab / Type 3 - 64 Notch
Water
GTI 83, Jetta 81, 85, 87, 91 TDI, 98 TDI, 09 / New Beetle 99 / SportWagen 05, 13 / Tiguan 18 / T3 92

[RedSquare]

Unless you particularly want to do the work yourself, you might consider reaching out to Jim Adney or one of the other folks on here who regularly rebuild/repair distributors for these cars. Jim or one of the other experts on here would likely be able to help offer an informed opinion.

I lack the skill/knowledge for it, so I recently had my stock distributor gone through and repaired by Jim, and I’m glad I did. Price was fair, time for the work was reasonable and I had confidence that he knew what he was doing. I’m not related to him in anyway and don’t want to come across like I’m trying to start a fan club, but I also think there is value in acknowledging folks who can be relied on to do good work. He’s not the only game in town - certainly other very knowledgeable and reputable people on here that also do good work.

[tasb]

I'm going to assume your distributor is a 311 G since this is a Type III forum. The canister for this distributor is a common one as it was used on the Beetle and Bus of the same years 1966-67(distributor# 113 905 205 K). The original canisters can be differentiated from others of similar appearance because the one you need has a star rib pattern on the front side of the canister.

I source good tested used canisters all the time on the distributors that I restore. I have had a small handful of customers contact me about a failed canister in twenty years. I source used ones because new are very hard to find after fifty-five years. When found they are pricey as opposed to a used part. I cannot supply the canisters alone as they too can be a challenge to find at a restorer's price. Be aware that when shopping for cores it's not unusual for them to have the wrong canister on them.

Again, assuming you have a stock carburetor since vacuum advance only distributors must have a matching carburetor to perform as intended. Your stock carburetor does not have the correct vacuum signal for a later aluminum housed SVDA distributor.

There are actually only a small number of different vacuum only canisters, the problem is telling them apart as Bosch left structural only hints to tell them apart. It was intended that only a trained expert could tell them apart.

If I yet again assume that you have a 1964, 1500 S model then pursuing the original ZV/JCU 4 R 3 distributor would be a good idea as they are excellent distributors. The 311 G will perform well until that time comes.
_________________
Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse

[Ossipon]

[tasb]

Not sure if you were using sarcasm here but without a working canister you have NO advance curve.

You may have missed the point that if you have original carburation a SVDA distributor will not perform well for you. Neither will the 010 and it is pricey. They will get you back to running. If you need to get it running source a German 009.

Replacing the canister requires removing two screws, detaching a spring,

https://www.thesamba.com/vw/classifieds/detail.php?id=1969038 Tell them you need one with the ribs on the canister.
_________________
Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse

[Bobnotch]

[tasb]

I would suggest not going with off the shelf parts as the quality of brand new parts like condensers is dubious. You want to go with restored factory engineered original and NOS point and condensers.

Vacuum canister specs:
311 G = @25 degrees from 65 mm/Hg vacuum
043 034 SVDA = @10 degrees from 200mm/Hg vacuum

My guess is that Bobnotch is getting full vacuum advance very early in his advance curve not what the VW engineers intended. His idle timing setting is possibly different than stock.

Nay sayer's might call out that I'm trying to make a sale here. Please purchase from another restorer on here (above I linked a different seller than myself). I'm just trying to assist from experience just like Bobnotch whom I'm not trying to pick a fight with. I'm also suggesting the OP fix this issue himself since he appears not to need a fully restored distributor.
_________________
Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse

[Ossipon]

I did not intend to initiate the battle of the best distributor option.
(Tasb: I appreciate your comments and suggestions on sourcing the cannister. I will do that.)
The reason I considered the 010 was that I had a "bastard 1200" years ago with dual Solex to make a, fake Okassa. I trusted that 010 with duals. It was a fun experiment, but not really that fast. And I should know. I knew about 009 issues from having one on my Super Beetle. It would just be OK as long as I did not try t0o hard.
The reason I am considering the SVDA was a just in case scenario. It is sort of a logic, you can never have enough distributors. I would rather have function than not. My comment about poor advance curve on a bad vacuum was meant more of an understatement. A pierced Vacuum line on a vacuum only distributor is a good lesson on that.
I know I can source a vintage 009 easily enough, I like the SVDA and know how to tweak with the springs. It is more of an issue as initially said, I want reliability over fully correct setup. I started with the body work instead of the brakes and engine first as I have confidence in my engine/ignition skills. Although I do not have a Dist. test unit. I know what makes a good unit and to me, it is how tight it is in regards to springs, plate and shaft.
_________________
Ossipon
VWs in my life:
Air
Type 1 - 59, 62, 63, 71 Super 68 KGhia/ Type 2 - 59 Single Cab / Type 3 - 64 Notch
Water
GTI 83, Jetta 81, 85, 87, 91 TDI, 98 TDI, 09 / New Beetle 99 / SportWagen 05, 13 / Tiguan 18 / T3 92

[tasb]

Fair enough, I've still got some bruises, been called names n such which causes me to disclaim some of my suggestions. Good luck with your build, I'll standby if needed.
_________________
Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse