lets talk Dizzy's...

[Anthony]

I think the vacuum advance on my 300 might be screwing up... wants to fall on it's face when accelerating... going through the carb again but can't find no problems there. it is a points condensor dizzy and if I am going to replace, I want to go back with electonic... OK Guru's, what do I want to go with to replace the points dizzy? part #'s and places to purchase would be wonderful...

[Toyz]

Anthony, the vacuum advance has little to do with your described problem. A flat spot on acceleration is often fuel related, although an in-correct curve or a malfunction of the centrifugal advance can be the cause. You can check initial and advance settings with a timing light after assuring that dwell and idle are properly set.
As to going electronic, my choice is and long has been one of the Pertronix systems, or Bobenhotep's equally (IMO) effective HEI module on Duraspark. That setup is easy to do, and probably the easiest to obtain immediate replacement parts if ever needed.

Paul

[bobenhotep]

The link for the HEI/ DS II system I use is in my signature block.

Dan

[Blackwaterforge]

Use a small hand held vacuum pump to check how much advance you are getting.
Check the centrifugal as well.
I have a dual advance distributor from a 73.
I kept the points. Simple and reliable.

[charliemccraney]

Vacuum advance is pretty easy to check. First disconnect and plug the port at the carb or intake, wherever it is. Use a vacuum pump to make sure the advance holds a vacuum. Then start the engine and use the vacuum pump to make sure it does advance the timing. Once it is determined that it works, leave it disconnected and go for a drive. Problem solved? Then it's probably the vacuum advance / distributor. Problem still exists? Then it's probably not the vacuum advance / distributor. When you disconnect the vacuum advance, it may affect the way your engine runs off idle and at lower rpm so you need to be sure that you don't confuse that as a problem.

[slick4x4]

''wants to fall on it's face when accelerating''

accelerator pump.... my first thought

[Anthony]

this happened on my way home from Slickstock and I gave credit to bad gas.. evidently not the problem.. on the way home we was running just under 60mph when we decided to get off at a rest stop just the other side of Peoria Illinois. when I got into the off ramp lane and let off the gas, it started missing like it wasn't getting any gas and even backfired through the exhaust once. after that. it would idle rough but wouldn't take gas smooth at all, had to "feather" the gas pedal to build up speed and even then it was spitting and sputtering like it was missing... we have already had the carb apart once and replaced the power valve and checked the pump, and the carb seemed to be working as it should. it still runs the same, spitting and sputtering...Wally is taking a second look at it tomorrow but don't think it is the carb... he said he was leaning to the dizzy not working properly... just fishing for options and suggestions... thanks for the responses guys...

[slick4x4]

That sounds like really weak spark...

Coil ? Voltage to coil ?

[Toyz]

I'm not sure if your carb has an inlet screen or if you may have already checked that; your symptoms certainly have the earmarks of a fuel problem. If you haven't done a pressure/ volume test, I would suggest adding that to the list of tests. Definitely check for mechanical advance, it should come in fairly early on the 300. If you don't have a spark tester, an adequate substitute can be made by cutting the ground electrode off a spark plug. With the plug securely grounded, a good ignition should be able to jump the gap. Carefully examine the distributor cap for carbon tracking. Also examine the primary wire in the distributor, it may appear fine but ground out as the advance moves. A replacement condenser also may be a good diagnostic tool.
At least it got you home! Good luck,
Paul

[Toyz]

That sounds like really weak spark...

Coil ? Voltage to coil ?

I really miss the old days when every shop had a scope to aid quick ignition diagnosis. I haven't used mine in years, but this is the sort of problem where they can be extremely useful!
Paul