[Geeto 67]

Originally Posted by tom s

you set the initial at 23?Dont think mine would start with that much!

No I set the mechanical advance at 23 degrees (rev to 3000 rpm and disconnected the vacume hose). I did this first since the initial problem that caused me to mess with the timing in the first place was a secondary backfire because the distributor walked.

Originally Posted by kenth

I think you have a lean condition due to either vacuumleak (bad flange gasket/cracked hose/s?) or clogged ilde circuit/misadjusted idle screws or a hotter than standard camshaft ( over 225 degrees @ .050").
Check vacuum in manifold with vacuum gauge.

Initial timing is usually set at idle speed, you may check the advance at 2500rpm´s though.

The cam is definalty a hotter cam, but I have no specs on it and I don't want to tear the engine down.

Don't know if the flange gasket is any good or not (the carb hasn't been off the manifold in seven years) but all the hoses look tip top. I am adjusting the throttle stop for the idle so it is possible the carb may need a teardown. Where would I hook up a vacuum gauge to check manifold pressure?

About the idle speed. do you set initial timing with the car idling in gear (D) or in park? I set the idle speed with the car in gear and then checked the initial timing. Should I re do it?

Originally I put the car in park and set the idle at 600, set the timing at 6 degrees initial, and then revved it up to take a reading on the mech advanced and total, I got 37 degrees mechanical advance and 50+ degrees total. That is why I decided to set the mechanical first and adjust the idle to compensate.

[Junkyard Dog]

23 degrees is nowhere near enough at 3000 rpm. Where are you getting your procedures?

Set the initial timing in Park, with the vacuum line disconnected, and with the vacuum leak plugged, of course. You are going to have to adjust your idle speed back down, and readjust it if moving the timing moves the idle speed, then recheck the tiiming.

It sounds like you "originally" (your last paragraph) did it correctly. Do it that way again . . .

Dieseling can be something as simple as not enough octane for the car. My GTO would diesel with 87 or 89, but not with 93 octane gas. If your engine is still original, you may be pushing it on pump gas anyway . . .

If memory serves, that engine was rated at 10.75 to 1 compression (someone will correct me if I got it wrong) and really works out to 10.25 to 1, which is still pretty high for iron heads.

[Perses]

I'm curious what the connection is between Sun Electric Corporation and Pontiac ?

[Geeto 67]

Originally Posted by Perses

I'm curious what the connection is between Sun Electric Corporation and Pontiac ?

Sun electric made the sun machines which allowed shops to test and "tune" (recurve) distributors. If you owned a car in the 1950's through the 1980's and had a shop work on it, at some point the distributor passed through a sun machine. They are a rare thing to see in a shop these days and recurving a distributor is a dying art.

Sun would get the maufacturer's specs and print them on cards. A mechanic would take the distributor off the car put it in the sun machine, and the sun machine would spin the distributor so you could check it at various rpm levels. Depending on the machine it could also give you readouts of certain information, set the advance, and tune the weights. The cards allowed you to "blueprint" the distributor according to the manufacturer's specs. I used to have a binder with a ton of old sun cards in it but it was destoryed in a basement flood (raw sewage otherwise I would have kept it).

Originally Posted by Junkyard Dog

23 degrees is nowhere near enough at 3000 rpm. Where are you getting your procedures?

Set the initial timing in Park, with the vacuum line disconnected, and with the vacuum leak plugged, of course. You are going to have to adjust your idle speed back down, and readjust it if moving the timing moves the idle speed, then recheck the tiiming.

It sounds like you "originally" (your last paragraph) did it correctly. Do it that way again . . .

Dieseling can be something as simple as not enough octane for the car. My GTO would diesel with 87 or 89, but not with 93 octane gas. If your engine is still original, you may be pushing it on pump gas anyway . . .

If memory serves, that engine was rated at 10.75 to 1 compression (someone will correct me if I got it wrong) and really works out to 10.25 to 1, which is still pretty high for iron heads.

The motor was rebuilt 5000 miles ago. It has 9.5 to 1 compression and used to run really sweet off 93 octane. When the motor was new the car was really fast (high 12's on slicks). I'm going to redo the timing, and yes the idle moves when you move the timing.

I am slowly coming to the realization that there is a distributor rebuild and a carb rebuild in my future.