Yes, the vacuum advance diaphragm on my engine was shot, and hence the source of the vacuum leak. It idled well, since vacuum advance hose carries no vacuum at idle.

Currently the hose going to the distributor is plugged -- meaning no vacuum advance, so the engine is running retarded under light loads. When I floor it, it runs perfect. After it warms up, even part throttle works great.

Does anyone know if there is an adjustable advance unit available for the stock A12 distributor?

The static timing is right on: I advanced the timing until it pinged a bit, then backed it off a degree.

I have a similar problem also but mine seems to be at all engine temps, Power is reduced when the primary circuit in the carby is in use but when you open up the secondaries, power returns to normal. And also when you try to adjust the idle, the mixture screw can be screwed all the way in and the engine will not stall. I thought this was an inlet manifold vacuum leak but I can't find one!! . I still run the standard A12 and Hitachi with extractors.

Any ideas????????

any update?


I still have the same problem after replacing/checking the ff:

new points, condensor, spark plugs, check timing, tuned the carbs, rotor cap, checked hoses and replaced blow-by hose, checked and cleaned the PCV valve as well, new oil, check wiring all looks good also dizzy cap - cleaned and checked for cracks

maybe the coil???

Any more ideas what to check?

Turned out to be a ... vacuum leak from one of the diaphragms.

I can't believe how much better the engine keeps running every time I fix another problem. I thought it ran well at first, then after tuning it up, and ran so much better. After adjusting the timing it even shifts better. Now my cold-engine performance is about 95% good. Still just a tiny shaking at very light throttle when it is cold.

I got this somewhere: HARD STARTING

1. Choke (Enrichener system) plugged, not properly functioning or improperly operated.
2. Inlet system air leak.

3. Restricted fuel supply. No fuel in float bowl.

4. Fuel overflow.

5. Plugged slow jet or passages

6. On high compression (over 10:1) engines, excessive voltage drop to the ignition coil can cause hard starting. A clear indication that this is the problem is that the engine wants to start after releasing the starter button.

1. Clean, adjust or replace; or read Owner

I'm getting the same problem, only when its cold... and its just getting cold here in QLD not even that cold (early mornings)
car will run good when temp gauge needle is around the middle area.

Quote:
ddgonzal
I was using this as a guide. High moisture levels in the air [humidity] often lead to carb ice.
If you think it is electrics, then this is the area to check first

Naw, Seattle is not really a cold place (just damp). It's been way above freezing (45-55 degrees), and the problem happens even after I've been driving for 5 minutes. It doesn't get better until it is fully warmed.

I'm thinking it is something basic like plugs or wires.

ddgonzal
I wonder if you are also suffering from carburettor ice. High humidity, low temp,... could be. When the engine warms up, & i assume that your air filter hot air system is working, the warm air melts the ice in the internal air passages & it runs better.

IF that is the problem, then i found that running the car for a few minutes before moving off is enough to provide warm air from the exhaust manifold. IF there is ice in the air passages, the carb runs rich & gives you poor mileage & bad running.
Yes, i know about the ignition, & this is a good thing, but just keep the carb situation in mind, as it is possible that you have two diferent problems at the same time.

OK, so I swapped in the B310 electronic distributor & coil. It's running much better.

I thought it was running good when warm, but now it is far better. Shifts are much smoother for some reason (and here I though it was 'cause I was getting old). It idles better too. I guess that means the old points, condensor or coil were on their way out.

After changing distributors, I had two problems:
- Starter barely turned it over
- Slight ping sometimes (I had to listen closely)
Retarding the spark 2 degrees cleared up both of these problems. My timing light has gone bad, so I timed it by sight and by ear. (I had timed the points distributor with a dwell meter and timing light).

But the main problem still remains ... the distributor swap only removed about 80% of the problem. I think there is a slight miss when it is cold. My next plan is to remove the plugs and examine them.