Distributor needs way too much advance

[Z-Luke]

Okay, before I posted this topic I wanted to make sure I got rid of my points set up to make sure it isn't a rubbing-block issue or something, along with the rest of my ignition equipment. So I installed Pertronix, new cap, new rotor, new spark plugs and ignition wires. The only thing I haven't replaced yet is the coil.

However, I still need to advance the distributor all the way it will allow to even run ok. If I retard it even a bit it starts to die. The vacuum advance is working, but it needs a decent idle rev to generate enough vacuum on the front carb. The engine only idles best if I take out the dizzy bolt and advance it past where the plate would normally allow, and even if I backed off for safety it would still be way past maximum.

Whats up with that? I was really hoping it was the points, but they're gone now. There are no timing marks that I can find on the car other than the notches on the flywheel, but they are useless with the degree markings, so I have to go by ear and by vaccuum. At max advance allowed with the bolt in, I get 15hgs vacuum. If I over-advance past the plate I can get it up to 18hgs. The centrifugal advance works based on the changes I've seen with the timing gun.

I haven't heard pinging yet at all, but I have serious afterfire out of the exhaust at 5000 rpm, which I'm told could be retarded timing. And when I say afterfire, I mean afternuke - scares the crap out of me.

Thanks!

Edited May 14, 2010 by Z-Luke

[Gary in NJ]

Sounds like a engine timing issue. If you are sure that the distributor was installed with #1 @ TDC, then you may need to look at the engine timing.

[ChrisZ]

Driveshaft that goes from oil pump to dizzy might be one tooth off.

Chris

[Arne]

Driveshaft that goes from oil pump to dizzy might be one tooth off.

Chris

This is my guess as well.

[Z-Luke]

Yeah the dizzy off by a tooth thing seems right. I'm not sure how to correct this, the shaft just sort of disappears into the engine.

I have a question; what's vaccuum advance even for? Obviously its not used for hard acceleration, since the vac would be gone when you open the throttle. So it must be just for cruising economy? Sound right?

[beandip]

The vacuum advance port on the carb is ported vacuum not the same if you connect to the engine vacuum. The vacuum advance is to give the engine some advance coming off idle or when the RPM are low. As soon as the engine speed increases the centrifugal advance takes over.

I agree with the others , being one tooth off.

Have you been working on the oil pump by chance ? I ask because the Dist. drive comes from the oil pump .

Obviously your timing is way off. I am running a ZX dist. and 16* advance with the vacuum advance disconnected. I pull 22 inches of vacuum at idle. I don't know what engine or head you have and the amount of advance you can run can be different with the different shapes of the combustion chamber. Arne tells me his engine pings with a setting around 10* I believe. I am using a P-79 head that has been milled some but the chamber shape is much different between these two heads.

Gary

[Z-Luke]

It's a stock L-24. Yeah my timing is way off, and I've never worked on the oil pump. The previous owner had the idle way turned up so it wouldn't die and said it had trouble starting. I advanced the dist and it runs good, but still doesn't seem like it's all the way dialed in.

[ChrisZ]

What i think you should do, is to set the engine at TDC, take off the dizzy and take a photo down the piedelsta so we can see the position of the drive shaft, the oil pump have to be removed then the shaft will come out, just don't do anything before we can see a photo, much easier to guide you then.

Chris

[Z-Luke]

I'll do ya one better by making a video. I'll extract a frame from the video as a photo.

[Bruce Palmer]

Previous owner was partially compensating for the distributor being off a tooth by the gap on the points.

[ozconnection]

However, I still need to advance the distributor all the way it will allow to even run ok. If I retard it even a bit it starts to die. The vacuum advance is working, but it needs a decent idle rev to generate enough vacuum on the front carb. The engine only idles best if I take out the dizzy bolt and advance it past where the plate would normally allow, and even if I backed off for safety it would still be way past maximum.

Sorry to be going back to the original posting, but I think that a few things here need to be sorted before you can get your timing as it should be.

Do you know how to find top dead centre (TDC) on cylinder one?

If you do, thats great and if no, we really need to start with the basics. Not that is a problem by itself, it just means you need to do some homework/research on how to do this. A factory service manual or other manual that discusses L engines is your best friend at this point.

Once TDC has been found, you need to look at your harmonic balancer (you called it a flywheel). Its the fan belt pulley thing on the front of your engine. Bolted to the aluminium front cover is a small jagged edged plate with numbers on it. Since you're on TDC, there should be a notch on the harmonic balancer that matches the zero (number 0) on the timing plate with the jagged edge. They should be lined up at TDC. Now get some white paint and mark the edge of the balancer exactly opposite the timing marker at zero. There should be a notch in the Harmonic balancer and it should line up already, sometimes the paint comes off or gets covered by dirt or grease.....clean it and see! If the notch doesn't line up, it could mean other things. Please post us your results at this point.

All this work so far will allow you to use a timing light to correctly set up your idle advance. As a starting point and with your vacuum advance hose disconnected and plugged, you could try 12 degrees advance. It should idle with this much advance, if not your mixtures could be off or your idle too slow.

I agree with everyone who has told you that your distributor/oil spindle drive is out by one tooth. Before you undertake changing its position, you must get the engine to TDC on cylinder 1 FIRST. Order of operation is critical with this kind of work. Do you have the confidence to do this yourself?

As A boy, I used to watch my dad do stuff like this and slowly built up the confidence to try things like this myself. If you're not sure you could find an experienced friend or mechanic to help you out until you become a bit more familiar with the trusty L.

Good luck, keep posting, tell us how you're getting on.

[Z-Luke]

Do you know how to find top dead centre (TDC) on cylinder one?

Is the cylinder closest to the front #1? I find it easier to find out if it's on it's compression stroke by looking at the camshaft to see if the valves are closed, but I really don't want to take the valve cover off again.

Once TDC has been found, you need to look at your harmonic balancer (you called it a flywheel).

I don't know why I typed in flywheel. Lack of proofreading. This is why I did poorly in University.

Its the fan belt pulley thing on the front of your engine. Bolted to the aluminium front cover is a small jagged edged plate with numbers on it.

No such aluminum cover exists on my car. I have seen them in photos of other forum members' rides, however this is completely absent from my vehicle. Thus, I am setting timing completely blind.

...Please post us your results at this point.

The best I can do is say that after over-advancing the distributor some more, the car labored more when accelerating at low RPM and started to ping when accelerating. I immediately lifted and set the dizzy back to the "safe" setting I've had for a while.

Before you undertake changing its position, you must get the engine to TDC on cylinder 1 FIRST. Order of operation is critical with this kind of work. Do you have the confidence to do this yourself?

I do but I'm not going to considering max advance at current setting gives me "close enough" and "safe" for now. Setting TDC on the proper stroke is the only worried I would have, as I'm too lazy to pull valve cover again after doing the valve adjustment a couple of times for hot/cold.

Good luck, keep posting, tell us how you're getting on.

After replacing the entire ignition system at this point, the car no longer afterfires at 5000 rpm, but does not rev out past 5500 rpm. I believe this to be a fuel metering issue at this point. Fuel delivery seems to be "lots" when testing the pump itself, float bowls are even and at the proper height, and the advance seems to be close enough. A couple of touches more and it starts to ping with 91 oct. It might be backed off a little too far right now, but I think I should still rev out.

I did recently replace the float needle valve on the rear carb, but this has not affected the car in any way so far. The reason I replaced it is because the rear carb inexplicably started a small environmental disaster.

Sadly I was too busy to produce any videos today but I'll try to get back at it tomorrow.

Edited May 16, 2010 by Z-Luke