Question on setting my timing

[Michael L.]

Re: Question on setting my timing

My feelings are with that kind of vacuum leak there is not enough of a combustible mixture getting to the cylinders to burn hence the erratic spark.

The plugs are sooted so just clean them good and try the engine.

I was thinking the exact thing but wasn't sure if it worked that way. I would think that the spark going down into the wire is independent on the ability of the plug to fire it. For example, if the car is totally out of gas and there is no gas to ignite, wouldn't the timing light still work perfectly when the car is cranking?

[Timothy B.]

Re: Question on setting my timing

Michael,

I follow your train of thought but I can't answer because I'm not sure if the timing light works if the spark does not jump the spark plug gap.

The difference may be that if the plugs are sooted the spark goes right to ground through the soot and does not jump the gap so current does not build up enough to flash the light. The coil will only generate enough current to overcome the plug gap so with a direct path to ground (soot) it's very weak. Maybe someone else that can explain it better than me will respond.

In any case start with the things you know are not correct and see how the engine runs. You know there is a vacuum leak and the spark plugs are sooted from exhaust carbon.

[Michael L.]

Re: Question on setting my timing

The B1 is a boat anchor... takes up to 18" to pull to the limit. Your engine likely pulls in the range of 10-14" at the lowest you can get it to idle, say 750-900, with acceptable idle quality, so you'll probably need a 8" B28 or 12" B26.

I believe you may have an improperly assembled and/or installed distributor. You need a 1969 Chassis Service Manual and a '69 Chassis Overhaul Manual may be helpful, too. Distributor installation is NOT in the AIM since the dist. was installed at Flint.

Let us know when you get at least a CSM. Don't touch the car until you do.

If I had a hundred bucks for every screwed up distributor assembly/installation I've corrected or helped owners fix over the phone, I'd be richer than Jeff Bezos.

Get the missing part for the carburetor installation and get it back to the GM design. I have a feeling that bubba has been all over your car.

Duke

Follow-up on this earlier post. I cannot begin to tell you what a enormous hassle this has been to get this thing running well. After installing the carb baffle that was previously missing, the car still ran like crap. Followed Duke's recs and took out the points and condenser and the wire to the condenser just fell out (see attached pic). Replaced the points and condenser and now, finally, after literally a couple of years of battling with this thing, the car is running well.

After getting the timing and dwell and air fuel screws optimized, the idle vac is about 11, so I'm guessing I need the 8" B28?

Mike

\condenser.jpg

[Robert K.]

Re: Question on setting my timing

Larry,
Would you happen to know what issue the "sealing second base" was from? I'm having a little difficulty viewing this copy and thought perhaps I could find it that way......Or, is there any chance you could resend as an .pdf "attachment" instead of a copy like this. If you're able to do that, I think it would be easily viewable........

Thanks,

Bob

[Lawrence M.]

Re: Question on setting my timing

Hi Robert,
I copied the article about 10 years ago. I no longer have that issue and do not remember which Month or Year of Corvette Enthusiast it was in. I tried attaching it again as an PDF, but that did not work. I sent you a private message.

[Duke W.]

Re: Question on setting my timing

Do a Web search for Airtex 4V1053.

Duke

[Dan D.]

Re: Question on setting my timing

Tim, you have current and voltage mixed up is all.

It is voltage that jumps the electrodes and creates the arc - not the current. The current is how hot the spark is, i.e. how many electrons are flowing in the arc.

If the plugs are sooted, that essentially shorts out the plug, and the current flows through the soot.

The coil charges when the points are closed (dwell), and the coil charges up until the points open, When the points open, the current through the coil in interrupted and the energy in the coil is transferred to the secondary coil intit has developed enough voltage to jump the gap between the rotor to cap contact, plus the spark plug gap. When the spark jumps, the coil voltage immediately goes to zero, and stays there until the points close, and the process then repeats itself again.

The timing light works when the induced voltage in the pick-up is high enough to arc the plug. If the plug is shorted out with soot, the voltage will never get high enough to trigger the timing light, or to fire the plug.

Until the arc happens there is zero voltage on the plug wire. When the arc does occur, there is current flow in the wire, but only during the time it takes for the spark to happen.

Hope this helps a little bit.

Dannnn