Question Regarding Specific Distributor Timing

[lbs_ft]

Hello all,

I replaced the 009 mechanical advance distributor on my 1966 1500 SP Beetle with a single vacuum advance distributor I bought in the classifieds. The specific number listed on the back is 113-905-205M. I'm running a new Solex H30/31 carburetor, so the distributor and carb should be a satisfactory match.

In order to properly time the engine after install, I went to the experts over at OldVolksHome in order to find out the details on timing this distributor.

On the Distributor Interchange page (http://www.oldvolkshome.com/ovhignbo.htm), my distributor is listed as coming in either a 68 Beetle or Bus running a 1500 or 1600 engine, which should work just fine for my engine.

Now onto the details, and where it gets confusing. Here's the page I'm referencing: http://www.oldvolkshome.com/ignition.htm#A1968M

This section says that the distributor I have is not the original, but it is a viable replacement, and to time at 7.5BTDC

[2nd67]

im faced with the exact same dilemma, my personal opinion is the vac canistor pn# should determine the timing specs?. look at the two specification lists that you posted. opt for the one that is for the actual pn# distributor that you have and not the "suitable substitute" criteria?

[KTPhil]

[lbs_ft]

Excellent, thanks for the responses guys...

Maybe this is a dumb question, but where would I find the PN for the canistor? As far as I can tell, the only thing stamped into the exterior is the Bosch logo and 'GERMANY'.

[KTPhil]

Maybe on the actuating arm in side the distributor? I forget!

Also check out:
http://www.thesamba.com/vw/forum/album_page.php?pic_id=576790

http://www.thesamba.com/vw/forum/album_page.php?pic_id=576676

I'm not seeing any numbers on those, either.

[lbs_ft]

Well, I went out in the dark and disassembled the distributor to get at the vacuum canister.

Turns out that there are no markings on the can at all, besides the ones I mentioned before. However, the back of the can does have the large 'star' pattern embossed into it. That being said, the actuating arm is squared instead of angled, which - according to the links you posted - should mean it's a replacement, but that doesn't make sense, seeing as it has the star pattern.

Having looked around after you guys pointed me in the right direction, I managed to find this thread where the OP had the exact same problem I'm having, and then I found a couple more threads like it. So it seems like I'm going to be timing at max advance to see whether I set at 0 or 7.5...

I'll probably take care of that tomorrow after work, and I'll be back to report my findings

Thanks again for all your help!

[2nd67]

if you had a degree crank pulley you can set your base/static timing and than connect the vac can and at the prescribed hg/rpm record the total advance and cross refrence that with the oldvolks distributor charts to id the vac can. allthough this method requires vac can/engine to both be healthy. i know you can also measure and mark stock pulleys so that is option #2.

[tasb]

What you have there is a mismatched vacuum canister and distributor. The vacuum canister with the star pattern on the back was installed stock on the 113 905 205 K distributor. What I am saying here is that you can make this setup work its just not stock nor what the OVH website says. that vacuum canister only gives you about 25 degrees of advance so you would set the timing static at 7 .5 degrees. The original stock canister gives you more advance at about 32 degrees so it is static timed at 0 degrees. The two canisters above are interchangeable mechanically. Some PO switched out vacuum canisters without realizing what they were doing. The 113 905 205 K and the 113 905 205 M use different advance return springs so no telling what you have without a picture of the spring.

The early (pre 1971) vacuum canisters do not generally have part numbers on them. Probably because there were not that many different units used through the time period and the physical design was different enough that you could tell what was what by its shape- if you were knowledgable. Later post-1971 canisters were the same size and shape and due to emission regulations in various places around the world the part number on the arm became necessary.

Here is some more helpful information on vacuum cansiters.

http://www.thesamba.com/vw/forum/viewtopic.php?t=307450&highlight=vacuum
_________________
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

[lbs_ft]

I had a feeling that they were mismatched... I'm also leaning towards thinking that the canister has been opened before, and the insides possibly replaced. The outside edge of the can, along the clamped lip, looks like it's been re-crimped. That is, it doesn't look nearly as neat, symmetrical, and smooth as the other cans I'm seeing, but that could just be me being paranoid. It holds vacuum just fine when I suck on the port, and it doesn't have any problem moving the advance plate in the distributor.

Either way, I have a degreed pulley, as well as a remote tachometer and timing light, so I'm going to set it to 7.5 per tasb's recommendation, and then rev the engine until I get max advance from the distributor. If I understand correctly, that needs to be as close to 35 degrees BTDC as possible, without going past it, right? Wherever I end up at max advance, I'll use that to set my base timing, whether it be 0 degrees, 7.5 or possibly something in between.

When I get home, I'll take a couple of pictures of the canister alone, then reinstall it and take pictures of the complete distributor and post them all up here. Then I'll get to work setting the timing and adjusting the carburetor.

tasb, in the link you posted, I saw your post regarding the ribbed pattern on the backside as well as the 'GERMANY' print being right side up, which leads me to believe it should be timed to 7.5, but I'll double check at advance just to be sure.

Thanks again for all your help and for all the info, I wouldn't be able to figure this out without you guys.

[KTPhil]

The vacuum advance is sensitive to load, not rpm, and it is hard to maintain a load sitting in the driveway. At best you can get a "flash" reading as you rev the engine quickly. Watch for the peak. If you miss it (or if your setup has some lag), then you will dial in too much advance, and then get pinging when you put a real load on it, up a long hill, for example. This can lead to engine damage.

[lbs_ft]

Well that's no good.

I'm trying to chase down an overheating problem that my car's been plagued with: after an extended period (15 or 20 minutes) of prolonged speeds at or in excess of 45 miles an hour, that little yellow warning light will start to flicker.

How am I supposed to perfect the timing if I can't read it at max advance? I guess I'm at a bit of a loss

[KTPhil]

It's not as hard as you think.

If you have a "mitivac" you can dial in a specific vacuum piped to the can. Just use the mitivac and look at the specs above for degrees of advance at a given vacuum level. Read it off your degree pulley or timing light setback.

Harbor fright has them pretty cheap. They can be used for brake bleeding with a little fixturing, too.

Or just note the advance with engine running at mid-to-high rpm, then suck as hard as you can on the hose to max out the vacuum advance, and read the amount of the increase. At least you will know the maximum advance the engine will ever see under high load.

Then note the static or idle advance. You now have your "not to exceed" values as you tweak things for performance and heat.

[tasb]

35 degrees of advance is a bit more than I would be comfortable with. I would shoot for 32 degrees at maximum.
_________________
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

[lbs_ft]

Thanks for the advice KTPhil, that's a huge relief. Luckily, I have a mitivac and I can use it to manually advance the timing. I would never have thought of using that, much less simply sucking on the canister even.

Unfortunately, I wasn't able to free up any time to work on the Beetle today, so it'll have to wait until tomorrow, but I'll be sure to follow your advice tasb, and set it to 32 degrees advanced max.

I was able to snap a couple photos of the canister itself, and then the full distributor with the canister installed. Hopefully everything looks correct and is compatible. Please let me know what you think.

[tasb]

Other than the fact that you vacuum canister is mismatched with your distributor, which you already know and can overcome it looks like your set.
_________________
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