GT HEI Distributer. Weber vac leak found

[Bolton454]

Just some interesting info.
In April I purchased a 1973 GT. I have spent a few weeks restoring it. It has a GM 30-1498 HEI Distributer on it. It was pretty noisy, so I took it apart last weekend and made a discovery. Someone welded a Bosch shaft to a GM distributer. However, the star magnets inside didn't quite line up so I had to shim the distributer body up from the block about 1/16th inch. The noise was caused by the rotor too high in the cap.
Also notice the Weber carb had a manual choke. However I could never get the thing to run right...vacuum leak. I have a Weber Progressive on my '64 Bug with auto choke. There is a small vacuum passage that controls the choke bypass diaphram. The Opel carb was not plugged off. I also connected the vacuum line from the distributer to the small manifold outlet rather than the delay circuit on the carb. It just runs better.
I have rebuilt the motor messed with just about everything. Poor car was rode hard and put way wet.
Kenny

[jeff denton]

Can you show us the distributor, Kenny? I've been wanting to do something similar to what you describe.

[Bolton454]

Here is a pic of my distributer.

[RallyBob]

Originally Posted by Bolton454 Here is a pic of my distributer.

Holy ! That thing is huge.

[David McCollam]

Originally Posted by RallyBob Holy ! That thing is huge.

Bob,

So are you says size does matter? It's inventive, I'll give them that.

Dave

[jlthunder]

It looks like it was for an 8cyl car and adapted for the 4 cyl. The Coil is located in the top of the cap(inside). The electronic ignition module is located under the rotor. Our '79 Camaro has the same style unit.

[guyopel]

This looks like a Chevete dist.

[Bolton454]

The parts store gave me a part number 30-1498. The distributer has 1112862 stamped on the side. It is just like my '86 Camaro except it has 4 plug wires and 4 star points on the pickup coil magnet. I'm sure it is out of some Chevy 4 banger. If you decide to make a retrofit, be sure to carefully measure the shaft length. Mine is a 1/16 inch too long and it caused the rotor to be noisy and the magnets did not fully line up in the same plane. Had to shim housing to block. Otherwise it works just fine.
Kenny

[Bill Hoffmann]

Originally Posted by Bolton454 I also connected the vacuum line from the distributer to the small manifold outlet rather than the delay circuit on the carb. It just runs better.

Your distributor must have a vacuum retard diaphragm only (like the '75 Opel distributors). If it was an advance unit you would have maximum vacuum advance at idle, no vacuum advance during acceleration.

[Bolton454]

I'll have to confirm the design. I need to dig down and get a good timing mark. I believe that it is advanced at idle, but not 100% sure. I'll try runnig it on the carb. circuit.
That carb. and I are another issue. I installed the heat shield to the manifold but I removed the center section (cut it out). I have Carb, gasket, manifold. The intake manifold has a bolt hole I used to hold the heat shield. I did this because I was fighting vacuum leaks. (The "fuel screw" ran best when all the way in. I am running a 50 idle jet.) The carb is working better. As I mentioned above, the choke circuit was wide open. I modified an open end wrench with a L-shaped bend to get to the carb bolts, one of which was broken out of the cast. I've had the car running for about 3 weeks.
FYI Took Opels Unlimited 6 weeks to send the parts.
Kenny

[jeff denton]

Perfect. I'm gonna copy that. It'll pass as stock GM. Vacuum advance won't be needed.

[Bolton454]

I connected the vac line to the carb and made some improvement. Also switched the emulsion tubes when I rebuilt the carb last weekend and got rid of my lag. (small one on the primary) This is a great forum.
Kenny