Retarded #3 timing on pre-doghouse distributors

[Dwighia]

I really appreciate all the responses so far.

By way of background, I delved into this issue because my ’71 stock Ghia 1600cc dual-port was running rough. Some hesitation from a stop: which is probably normal for a 009 Dizzy. However, at a constant speed, say 35 mph, the engine has this annoying sputtering, bucking, hesitation feeling -- kinda like it was missing or something.
Stock engine except for the 009dizzy (1600cc dual port, Solex 34 PICT-3 Carb)

So, I did a complete tune-up, i.e. :
Valves .006 all around, stone cold
New Dist. Cap and rotor – Bosch
New Condenser – Bosch
Points (dwell = 4,
Timing = 12d @ idle and 32d @ 3k rpms from #1 cylinder. Using an advance timing light.
Plugs looked great
Plug wires look fine, but not replaced recently
No debris in the fuel filter.
Solex 34 PICT-3 Carb has nice strong squirt from accelerator pump
Finally adjusted the idle= 820 RPMs at the carburetor. (although the idle readings jump all over the place)

I measured dwell and RPMs using an “Alltest 3707 Digital Engine Analyzer” which has a “Worn Distributor” light indicator. This light blinks!) It blinks even more on my other ’68 Ghia. (And that Ghia’s vacuum-only dizzy also has the #3 cylinder retarded by 2-3d.) So not sure how reliable this blinking light is and not sure if it is supposed to be blinking or steady. The unit says the light indicates “more than 2d dwell variation between cylinders – caused by worn cam lobes or bushings”. However, the dwell reading does not jump around like the idle does. So maybe this blinking light is just indicating the difference between the #1 and #3 cylinders?

The 009 Distributor was installed in 2009, or 37,000 miles ago. It is an off-brand Spectra Premium VW06 and it has NO Notch on the rim to indicate where #1 cylinder should be. (I believe “Spectra Premium” translates to “piece of junk” in German.)

So, thanks to the generous folks on Thesamba, I discovered that my 009 retards my timing on one of my cylinders, and since my dizzy was installed backwards, that retardation was on the #1 cylinder, it meant that I have been timing my Ghia incorrectly since 2009 – ouch. And worse, I’ve been timing the engine too high, like 35d – double ouch.

I realize my situation is rather unique. However, I am certain that I would never have discovered my error in timing (by checking the difference between the timing readings on the #1 vs the #3 cylinder), if it had not been for this thread. So, thank you everyone.

Perhaps this is something others should check if their engine is running hot or pinging or something.

Now to answer the questions so far:

Rockerarm: I’m flipping my dizzy and lowering my timing as suggested. My engine has never seemed particularly hot, but will verify with my meat thermometer. If I do replace the dizzy, my research (oldvolkshome.com) says that stock is “Stock Distributor: 1971-1973 1600 twin port engine (AD, AE series engine numbers) with the DOUBLE vacuum (dual diaphragm) distributor (two vacuum lines to the carburetor)”. Would anyone care to suggest a supplier? Thanks.

Busdaddy: I only have a regular pully with a dimple for TDC and a v-notch for approx. 5d ATDC – which I ignore. I read my timing using an advanced timing light aligned with TDC dimple. Thanks.

PJMS: My deceased mechanic installed this dizzy the way it is. I’ve never taken it out. I would like to go back to stock for a ’71 Ghia. Any suggestions for a reputable supplier? Thanks.

Ashman40: Yes, I’ve searched (without success) for pictures or information on distributors that DO NOT HAVE A NOTCH. But thanks for the pictures with notches. Option-1 Duh, what was I thinking --of course the dist. Cap only goes on one way. Option-2, This is probably what I will do for now. I’ll pretend I’m in England. Option-3 I will verify the top of the drive gear looks like your picture, but the rest of the procedure seems a little over my head. Thanks.
Dwight
_________________
'71 Ghia Sedan
'68 Ghia Convertible
'84 Vanagon
If you dismantle a VW engine and reassemble it enough times, will you end up with enough extra parts for another engine?

[ashman40]

[Dwighia]

Update:
I took AshMan40’s excellent advice and went with option #2. i.e.
1. I verified that my engine was indeed positioned at #1 cylinder by rocking the pully and watching the valves not move when at TDC and rotor pointing to 4 o’clock.
2. Took the dizzy out and verified that the smaller half of the offset slot inside the dizzy tube was indeed toward the rear of the engine. Also found this guy’s video very helpful https://www.youtube.com/watch?v=eaFoOzIKR4E

3. Reinstalled the dizzy and marked the side body of the Dizzy with the new position of #3 and #1 wires. Then rotated it 180 degrees. Now the new #1 cylinder wires are again at the 4 o-clock position.
4. Rewired the dizzy cap.

Here are my new numbers:
• Dwell 47-48
• Idle = 818
• Timing @ #1 cylinder 10 BTDC at idle and 28 BTDC at 3k rpms
• Timing @ #3 cylinder 5 BTDC at idle and 23 BTDC at 3k rpms

The engine actually seems to run a little better.
There is the usual 009 dizzy flat spot from idle, but otherwise works rather well. I continue to suffer from a mild form of sputtering while driving at constant speeds, but I think I can live with it.
Still, I might want to go back to a stock double vacuum distributor at some point, should I find one at a reasonable price.
Otherwise, all is well.
I really appreciate all the help from everyone on Thesamba.
Dwight

_________________
'71 Ghia Sedan
'68 Ghia Convertible
'84 Vanagon
If you dismantle a VW engine and reassemble it enough times, will you end up with enough extra parts for another engine?

[tasb]

Your clip for holding the condenser wire is upside down and not holding the wire in place. It can come loose easily and short out leaving you stranded. Flip it around 180 so that the fork holds the black plastic block in place.
_________________
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

[busdaddy]

[tasb]

[runamoc]

I ran across a rebuilt engine that had the distributor gear in 180º 'off'. I took out the distributor, took the spring off of the 'drive' on the end of the distributor, pushed the pin out, rotated the drive 180º, pushed the pin back in, installed the spring. TADA If you do that, your distributor will 'look' correct and work correctly.
_________________
Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires

[PJMS]

[tasb]

Interesting and valid assertion. Can you support it with documentation?
_________________
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

[PJMS]

I had gone through all of this 10 to 15 years ago, so I will have to go dig up my records. I am sure, though, that some of it will have been archived on the various forums as well. One of the problems for the 'show proof' requirement is that it is sort of like asking someone to prove that something, which never happened, actually never happened! if you see what I mean.

[PJMS]

It is going to take a while for me to find and produce the research I did into the subject of the ignition retard on #3 cylinder, which began in the early 1990’s and then concluded about 2006. In the meantime, I can sort of explain what it is all about.

First thing to remember is that the VW engineers were like scientists and their reasoning would seem odd to most of us, but once you make that translation then things start to make a different kind of sense. Gene Berg was the one who got me started on this as he insisted that it was nothing to do with the position of the oil cooler. He wasn’t the only one who poured disdain on the idea that the cooler was the problem, as just about every other VW trained mechanic I spoke to, who knew anything about it, had a similar story.

As the myth goes: VW built millions of Bugs with one of the cylinders constantly running hotter due to the fact that they placed the oil cooler inside the flow of cooling air to that cylinder. To cure the problem, they introduced a distributor which retarded the ignition to that cylinder by 4 degrees, until they redesigned the cooling system taking the oil cooler out of the cylinder airflow. Sounds perfectly reasonable, except for the fact that there was no VW explanation to that effect.

So what is wrong with the myth? The main ‘red flag’ is that #3 was not the only cylinder downwind from the oil cooler! When I checked the VW (deep magic) specifications I found that not all distributors had the retard feature. It seemed it was almost exclusively a feature if all-vacuum advance distributors (for both Type 1, 2 and 3 vehicles. This was backed up by the VW trained mechanics who all insisted it was an issue that related to the advance curve of certain distributors. This, however, did not answer the question of why this advance curve affected only #3; what made it so special?

The important thing to remember about air cooling is that it is really the air density or air mass which is important, not so much the ambient air temperature. The more air you ram through the fan housing the more heat is transferred out of the engine. It was a relatively small amount of air that passed through the oil cooler (limited by a baffle) forcing most of the air over the cooler, which in turn forced the exhaust from the cooler to flow out at the base of the cylinders (not the hot part). There were no vanes required on that side of the shroud as the oil cooler provided all the direction needed; which is why, when people thought relocating the oil cooler would improve things, it actually made it worse.

It turns out that the temperature of #3 is affected by a combination of its location and the efficiency of the inlet manifold exhaust pre-heat. #3 is the furthest cylinder from the muffler, which means that the hot exhaust gases remain in the exhaust manifold longer than any other (#1 being the next hottest) and that negatively impacts the temperature inside the combustion chamber. Due to the right to left direction of flow of the inlet pre-heat, the left side of the manifold would not maintain fuel atomization as well as the right, which also affected the temperature in the chamber. However, all this only became an issue with the advance curves created by all-vacuum advance distributors; which seemed to exacerbate the problem. And the ‘problem’ was not so much the increased heat but that it caused the ‘burn’ to complete more rapidly so the engine effectively 'fired' at uneven intervals. The retard feature did not actually cool the cylinder, but simply brought the completion of the burn cycle in line with the other three. Other improvements, which may have helped, were the shortening of the manifold length, the improved heat exchangers, which essentially removed heat from #1 and #3 exhaust manifolds, and the dual pre-heat or left to right single pre-heat inlet systems.

The use of all-vacuum distributors essentially came to an end with the advent of the more strict emission controls which also necessitated the Dog House cooling system. The general method for improving emissions was through a more complete burn in the combustion chamber; which is easier with a lean mixture. To control the resulting heat across all cylinders, they needed more air, and more control of precisely where it went. This meant moving the oil cooler out of the way (more capacity) and replacing it with directional vanes. The relocation of the oil cooler was nothing to do with the temperature problems in #3 and if they had used the all-vacuum advance distributors with the Dog House system, they would have most likely still needed the 4 degree retard on #3. The ‘proof’ of this is in the fact that this was precisely the case with the Type 3 engines fitted with the all-vacuum distributors as the oil cooler had its own separate cooling air, just like the later Type 1 Dog House system.

And if that is not enough, VW continued to supply Type 1 models with 1200cc engines and the old in-house cooler set-up until 1985. None of these engines, fitted with vacuum/centrifugal advance distributors, used the retard feature.

Hope this has explained my understanding clearly.

[heimlich]

[airschooled]

[Frederik]

The following is from a service bullitin from Bosch 1st of Jan 1965 pointing out changes in distributors for vw.

Loosly translated:

Formerly VW 1500N (type 3) was fitted with distributor ZV/PAU 4R4 and ...R6. This distributor types was from chassie No 0221975 (aug. 63) replaced by the distributor 0 231 147 002 (ZV/JU 4 R3) with only vacuum regulation and smaller vacuum can. From the start of the year 1964 vw 1200 (type 1) and vw transport (type 2) also are fitted with this new type of distributor and in August it was introduced as 0 231 147 002 -JU4 (R). The vacuum can on this distributor is 65mm. With this distributor an asymmetric points cam shaft was introduced with counting from cyl 1 has 0-90-182-270 degrees between the cams highest point (My note: 2deg at distributor=4deg at engine).

With this new distributor a change of the carburetor was also made. From carburetor number 238 225 the vacuum port has been moved 8mm closer to the throttle plate. In the vacuum connection a drossel jet is fitted. This in combination with the new distributor evens out the pulsating vacuum signal.

The following combination can be made:
The new carb with the new distributor
The new carb with the old distributors
But not the old carb with a new distributor

Change for 1500S:
Before it was fitted with distributor 0 231 150 001 (ZV/JCU 4R3) with centrifugal and vacuum regulation. This distributor was from aug 1964 replaced by distributor 0 231 147 007 -JU4(R) with asymmetric points cam shaft as described above, but with a bigger vacuum can of 85mm.

[Frederik]

Me to think the "myth" part is that the retarded No 3 has anything to do with a obstructing oil cooler/ lowering the temps. As the bullitin above points out type 3, 1500N was the first to get this change and altough the text doesn't say it straight out it feels like it (as previous pointed out) has more to do with the vacuum signal and a evolution during and for the 60's vacuum distributors. The mechanical/vacuum (SVDA) cast iron distributors before this didn't have it, but even type 3, 1500S got it when they went from the one year only ZV/JCU4R3 (SVDA) to the vacuum only distributors. As previous chart points out the later aluminum mechanical/vacuum distributors didn't have it (or at least not the ones in the list). Other car manufacturs at the same time (mid 60s) also got assymetric points cam shaft, opel 1964 for one example got a 0-92-180-272 degrees points cam.