6 degrees BTDC is a little low. try a little more timing. should stop your backfire/cough and improve the vacuum.
6 degrees is what it calls for in the Haynes manual and the Chiltons, so that's what I was going with. If you think bumping it up to 8 or 10 might improve things I will definitely give it a shot. But first thing tomorrow I am pulling the plugs to read them and see if they look ok now, check & verify the gap, and then do a compression test while I have them all out.6 degrees BTDC is a little low. try a little more timing. should stop your backfire/cough and improve the vacuum.
Well I don't think the compression test will show me anything (at least I hope not, because if it does then it means something serious!) but it will be good to do one and know what I have (engine has not been rebuilt so I am not assuming much, but will be nice if they are all relatively close to each other), and since I'll have all 8 plugs out to read & check gaps its as good as time as any.Hello Cracker289,
A compression test is always helpful - BUt I don't think
you will find an issue there.
I know you have done a LOT of quality posts here and I have
read many and learned a lot. BUT
As cindys_sn95 has said - move the timing to 10BTDC.
The specs all call for 6 but she will run much better at 10.
Next - - even the PRO's miss the little stuff sometimes.
I would make sure the wires are all run correct. You would be
surprised at how well that motor will run even with 2 wires in the wrong
spot on the cap (firing order).
TRUST me Cracker - -I know you know a LOT but sometimes a fresh set
of eyes can pick up something little.
After the compression test - -I would turn the mixture screws all the way in
to a gentle seat - -then I would back both off one and a half turns. This is a
good starting point. Then watch the vacuum and set for the highest number
as you know.
For kicks - -I would try to eliminate a SLIGHT vacuum leak. Take a can of
starter fluid and spray around the base of the carb when she is running.
If after checking things and checking for vacuum leaks - -it may be time to
rebuild or replace the carb. I WOULD NOT do any major changes until
you are certain the issue is in the carb.
Figured I offer a few little tips to get you going - - It may be just something little.
Trust me on this - -I don't think you have a major issue just a frustrating one.
From earlier: "Also made sure my HEI is getting 12 volts while the engine is running (I connected the original positive wire for the coil to a relay, and then let the relay keep a steady flow of power to the ignition). "the original positive wire for the coil is a resistor wire! NOT full 12 volts. with it running, check the voltage.
Oh I thought you were under the impression that I was feeding the HEI with the original 8 volt points power feed. I'm only using it to switch the relay on and off.i saw what you posted john, that is why i stated the original positive wire is NOT 12volts! you know what....nevermind.