Distributor

Pritchard · 06-02-2000, 07:48 AM

Hi guys-

I have a '74 914 with a stock 2.0L. I have a distributor question. How do you know when a distributor is going bad?

Another question. I have a distributor with a id. number that ends in 009, but also has vacuum advance and retard hooked up to it. I have read in this BB that this dizzy is not the most desirable. I have also read that there is a reasonably priced replacement that ends in ...253 or something. If you have info on the subject of dizzys I would appreciate your input. What is the difference between the 009 and the original as far as advance curve?

Dave at Pelican Parts · Dave at Pelican Parts's Garage

I think the one you have is the desirable 1.8 distributor. The "009" that you don't necessarily want is the *Bosch* part number, not the VW part number. The VW part number should start with 022 or 021. I think the Bosch number starts simply with a single 0.

A distributor generally doesn't go bad. It can develop play in the shaft, which makes the shaft wobble. The advance plate can wear, the points *do* wear, and various pieces can need some attention. But the whole distributor itself doesn't usually go bad.

--DD

Pritchard · 06-02-2000, 11:08 AM

Perhaps I should have elaborated on the symptoms that I am experiencing. I have done a lot of work on the car and it is running very well when the engine has had a few minutes to warm up. The time that it takes in between startup and warmed-up the engine still runs OK, but it hunts a little and is sluggish responding to the throttle. I advanced the distributor about 10 degrees and things have improved. I can live with this adjustment if it will cause no premature engine wear (I've heard that it is hard on the valves).

I have checked the AAV for leaks and operation and all is OK. All vac. lines are new and tight. Fuel press. is 28psi. Still haven't been able to use the Wide Open Throttle settings described in tech. articles. Can't get correct/consistent/in-the-range readings on ohmmeter from throttle position switch.

Maybe I'm hoping for too much, but I'd like to have the engine running like it did 26 years ago.

If the distributor wobbles a little, could that cause a slight miss every now and then?

Pritchard

John Rogers · 06-02-2000, 11:20 AM

I tried to find a spec a while ago for distributor wear but had no luck. What I did to determine if it is worn is to hook up a dwell meter and rev the engine up/down several times and the dwell should not change. If it does that means the timming is changing and that is not good. About the only option is replacement o0f the distributor (new or rebuilt). Until I replaced the points with Compufire units I only use the Bosch points since they seem to work the best, but are affected by radial wear the most. A points replacement system such as Compufire is mostly affected by axial wear and will cause the magnet disk to break. Make sure the total advance is set to the spec, slight deviation will hurt performance and lots can cause possible engine damage. Good luck.

Dave Bell · 06-02-2000, 11:56 AM

Concerning the Distributor -

I recall that Haynes mentions that on a worn distributor the dwell angle will change by more than a degree or two over the RPM range of operation. I had that symptom on my 914 when I bought it, but it was not the source of the problems that you are describing.

I did buy a rebuilt distributor from the FLAPS and it was rock solid on dwell... in the mean time I switched to an electronic ignition so that dwell is a don't care issue now.

Other dumb things I have done is not tightened the distributor down enough or not inserted it down far enough so that it actually pushed up slightly and stopped turning!!!! but the results of that are very severe... things stop running altogether.

Now to your warm up symptoms.. the sluggish response and idle hunting.... I have similar problems of sluggish response and low idle for the warm up period... and while idle does not hunt around, it seems to settle to a different value depending on what day of the week it is.. and it I don't like it!...

Let's settle one issue quickly... if the problem bothers you, then you are not expecting too much to want it fixed no matter what age the car is!

even after all of my ignition upgrades, there was only a minor change in the problems during warm ups. I have replaced hoses, checked sensors, sealed things up and checked fuel pressure etc.... still got the residual warm up problem.

I am installing a O2 sensor which may help to catch fuel mixture problems... but I am presently suspecting some type of FI problem during warm up... I plan to keep at this problem until I eventually figure it out because it bugs me too.

In the mean time I installed a dash mounted 1000 ohm potentiometer in line with the Cylinder Head Temperature sensor. Dialing in a more resistance/fuel mixture richness during the warm up period seems to help a lot... which make me thinks it is some sort of FI problem during warm up.

Let me know what you find out.

- Dave

JP Noonan · 06-03-2000, 02:18 PM

Advancing the timing that much (assuming that it was close to spec to begin with) can blow up the motor from detonation. Advancing the spark does give VW's a lot more power but even without detonation it overheats the motor. Also in your case it is a band-aid fix.

Use a vacuum pump (Mity-Vac sold at FLAPS) and test to see if the vac advance/retard diaphram is working. As you apply vacuum the points plate should move, if not make sure the plate isn't seized, if it is free the vac can is bad. I had one go bad, wouldn't hold any vacuum, and causes all kinds of probems.

Another problem I've had is the advance weights sticking from rust. Usally this means either no advance if they are really stuck, or the advance comes on all of a sudden, and then won't go back down, neither will the idle.

There are also two little springs in the distributor that control the advance weights, they can rust and break off, this throws off the advance curve, or the advance is on all the time. Found a '72 with one spring broken, but the rest of the dizzy was in bad shape too.

Besides the vac can all the parts I talk about above are under the points plate. So unless you take the plate off it is hard to inspect. You can take the FI points out of the bottom of the distributor and look for rust or parts to the springs.

Don't ask how I know, but check out that the vac lines from the throttle body to the dizzy are correct. There is a diagram somewhere on this site.

Look at the timing and dwell article then set them to spec. Check the spark plugs to see if it a problem with all the cylinders or if just one looks a lot different from the rest.

Robert Helt · 06-03-2000, 08:08 PM

I've only had my 914 for 6 months, but have been playing around with these crazy 4-cyl. opposed engines for years and my 2-cents is this.
These engines don't need warming up! In fact, the minute you fire the engine up, you should be concerned with heat rejection. Generally, we these types of air cooled engines, once you have fired the engine, you should roll out moderately then begin your acceleration curve.
The hunting is predominate with these types of engines, the problem with hunting at start is strictly air temperature, air mass(density), fuel. Dave Bell's explaination of additing additional resistance, variable type, in series with the CHT is what compensates. Since 1986, during my travels, different locations like LA, Monterey and the desert., my hunting had varied. (I know you think I'm nuts!)
I still don't know how to warm these engines up before I drive off over the last 20 years. But, when the car is in the garage day and night before the next morning drive, it never hunts.....