Distributor Seems to Retard on its own....SOLVED!

[Chinaclipper]

I am having an interesting thing happening to my timing.
I have had the car running and driving now for maybe 500 miles. When it is running "warmed up, it seems to be running fine. I set the timing (statically) at 7.5 degrees BTDC, as per suggested.
Altho, I am noticing sluggish, terrible flat spots and off idle hesitations.
I am thinking timing, and sure enough, when I check it statically, I am always about 4 to almost 10 degrees retarded when I check it. Yesterday I re-set it at 7.5 degrees BTDC, and then drove maybe 30 miles, at highways speeds, and sure enough, when I went to recheck it statically, it had retarded to about 3 degrees BTDC. I did do a forum search, and saw something mentioned about some wearing of the lobes or something.

I have what (I think) is a stock SVDA, with a 34 PIC carb.
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[Glenn]

Set the timing 28-30° btdc @ 3500rpm with the vacuum hose off.and the carb plugged.

Make sure you have it on the correct vacuum port on the carb.
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[vamram]

In my experience, static timing is good just to get it started. Follow Glenn's advice using a timing light, then test again - drive, etc.
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[ashman40]

Remove the distributor cap and grab the rotor with your hand. Rotate it CW. It should feel like you are compressing a spring. Release the rotor and it should spring back to it's original position. This is the mechanical advance working.
If the spring back seems sluggish or gritty the mechanical advance mechanism may be in need of lubrication. To do this, remove the rotor and look down the top of the shaft. There should be a felt pad. Drip some engine oil onto the pad. If the pad looks very dry, add extra. Oil drips from this pad down into the distributor to lube the internal mechanism. You could even rotate the rotor back and forth to work the oil in.
Going forward, add a few drops of oil each time you change the oil... You know, that little bit of oil that still remains in the container at the end of the oil change? Now you have a use for it!


When you have a min, post the model number stamped into the body of your distributor. Better yet, post a pic!
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[a8ked]

I had a similar experience to yours. Are you sure the distributor clamp is tight? Try turning the distributor AFTER you've tightened the clamp, it should not move. I needed to replace my clamp because it would not tighten up enough and would slip over time under load.

[baldessariclan]

Number one, you need to get and use a timing light when setting your timing. The static timing method isn't very accurate, and is generally used to just get the timing into the initial "rough ballpark" -- i.e. where the engine will idle long enough so that a timing light can then be used to set the timing correctly.

Number two, if you don't have an engine analyzing meter with measurement functions for engine RPM and dwell, you'll want to get and use one of those as well when you're doing your tuning. Points need to be set first to the correct dwell range, and then the timing can be adjusted after that (i.e. since dwell affects timing, but timing doesn't affect dwell).

The lobes on the distributor shaft can wear over time, but not anywhere near fast enough to account for the behavior you're describing. If you're using really cheap/crappy points, the little rubbing block on those might be wearing down quickly - ? Otherwise, I'd suspect your distributor clamp may be set a bit loose (or is perhaps loosening up when engine running - ?), as noted by a8ked above.
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[ashman40]

[Chinaclipper]

[halfassleatherworks]

Did you lube the cam lobes for the points with grease?

[Chinaclipper]

[bsairhead]

When you suck on the tube, Do you block off the end with your tongue and wait 10 seconds?

[heimlich]

Grab the distributor and try to turn it with your hand. If you can turn it the bolt isn't tight enough.

Disconnect the hose from the carburetor and plug the hole. Set the timing at 7.5 degrees to the right side of the engine at or below 900 RPM. Then reconnect the hose to the carburetor. Go drive it around. Nothing should move when you check the timing again.

If you having a flat spot and you did the timing above correctly most likely your vacuum canister is blown.

Change the condenser out just to rule that out. It can cause issues sometimes.

Check your rotor and inside the cap.
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[Chinaclipper]

[Chinaclipper]

[wcfvw69]

If you have a Mexican Bosch 034, you're fine. They are excellent distributors since Bosch made them in Mexico with their tooling. I've restored 100's of them and they have the same internal parts as the German made versions. The specs are the same as well.

You need a Mighty vac hand vacuum pump to check the vacuum canister. The tongue test doesn't work.

Under the rotor is a felt that should have a few drops of oil added every 3k miles. It lubricates the upper points cam on the mainshaft. If you twisted the rotor and didn't feel it pivot against the advance springs then it's possible it's stuck. I see this a lot of distributors I restore. The previous owners never lubricated that wick.
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[VW_Jimbo]

What is your idle speed at?

What carb port are you vacuumed into?
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[Chinaclipper]

[Chinaclipper]

I got my timing light Thursday. It didn't work! I sent it back, new one came today so.....

1) First I checked vacuum. At idle, side port 0 mmHg. AT 1500+rpm, snapped up nicely to 20 mmHg. Looks good there, right?
2) Put a witness mark on the dizzy. Nothings moving...
3) I took it upon myself to remove and clean (as best as I could) the dizzy, and lube the moving plate and lobes.
4) Checked motion of plate with Mighty Vac pump (thx HF) It seemed to be moving fully (I think) with 15 mmHg vacuum, and the vacuum looked like it was holding, maybe s-l-o-w-l-y falling....(boring video-BTW, whey is the darn thing so low quality??)

Link

5) Set the timing at 7.5° BTDC statically. Took off vacuum hose from side of carb.
6) Confirmed setting with light-7.5° BTDC. Good...
7) Replaced vacuum. Ide setting still at 7.5° BTDC. Then ran it up to 3000 RPM. Got maybe 15° of advance. Did it about 5 times.... waiting a few a seconds between. Averaged about 15 ° BTDC . couple of times maybe 25 ° BTDC, but it wasn't consistent. Drove around for maybe 20 miles; 55 mph highest, but mostly in-town speeds. Rechecked the timing statically.
Yup, it had moved, this time advancing to maybe 10° BTDC.
Do I need a new distributor?? Suggestions? I'd like to keep the SVDA format-don't wanna go to a .009 or a DVDA
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[heimlich]

Vacuum looks good. It's not leaking down fast enough to call that a leak. You should be getting about 8 to 12 degrees of advance from the vacuum canister. That little movement will make a lot of advance.

From the mechanical portion of the distributor you should be getting 20 to 25 degrees advance from the distributor.

If you set the timing to 7.5 degrees at idle (less than 900 RPM) how does everything work?

No need to buy a new distributor. That one can be rebuilt very easily if it needs it. All the parts for it are available.
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Restored Distributors Available (<--Click here)

[baldessariclan]