[shaker455]

Originally Posted by formulabird428

Hoping I can get a direction from the PY forum:

Symptom:
Starts right up, idles nice when cold (have to feather it until about 140F). I drive it around and it runs great. One thing I do notice is that the A/F ratio is a little higher than normal -- maybe 0.5-1.0 points higher. Where it used to idle at 14.5 to 15.5, it's now from 15.5 to 16.5. Coming off of a cruise and stopping to idle, it goes above 18.0. I get it a little throttle, and then let it rest to idle again, and it returns to 14.5 to 15.5. Again, car has always done this, but it just "seems" to be a little leaner. In light throttle, it's about 12.5, which is pretty much where its always been for the last 5 or 6 years.

After about 25 minutes, it breaks up bad. Pops through the exhaust once or twice. I pulled it in the driveway, very hard to start. Backfires a few times. I actually had to pull it back in the garage today, since it wouldn't start at all afterward. Pulled Cylinder 1 plug and it was dirty, threads were wet, but tip was black-brown.


It has an HP 830 Holley with a new baseplate. Jets are something like 79 / 84 or something like that. I do have the back blades cracked open to allow for more air at idle. The T-slot is .030" showing.


Some components are old, but I don't drive the car more than 200 miles per year.


MSD 6AL ignition w/blaster 2 (coil is about 5 years old, 6AL is about 8 years old)
NGK plugs (about 4 years old, 1500 miles)
Holley regulator (this thing is all over the place, could be a problem here). I can't seem to set it and have it stick to a number. It will idle at 10, then drop to 4, up to 7, etc. Any recommendations for a better regulator?
Recently set the lash @ 0.020 / 0.022 per Reed Cam Card, but it is smooth as glass up through 5k rpm (when cooler - 160 or 170, not 190F hot).
Not that this matters, but oil pressure is good.

Any thoughts? Fuel delivery? Carb? Regulator? Ignition?

Thanks in advance.

You have a very long history of your combo not running right.
Bring it here & well help you!

[ta man]

What fuel pump?

[formulabird428]

Update:

In addition to the original post, I did try and take the timing. I thought it was because the light was hitting the water pump at first, but come to think of it, I had a hard time reading the timing. It did seem to bounce around 12 to 16. Maybe another sign of ignition.

The weather was much cooler when I started it up the next day. Up to that point, I hadn't changed anything yet. Only checked the lash (no problems) and took apart the regulator (appeared to be fine). It fired right up, ran perfect as it has for the last several years. Assuming the problem was the coil, I tried to heat it up by driving around town. Water never got above 180 but oil was a nice and hot 235. Despite my attempts to get it to repeat the severe miss, I could not. It did break apart a little, but nothing like the previous day. I changed the coil anyway and there didn't seem to be any change. I had to put the car away and get ready for another event, so I could not continue testing.

I think my next steps will be to get a better regulator. This one goes from 7 to 11 to 2 all in one cruise. Fuel pump is Holley Blue. About 7 years old. 1/2 line to #8 to 2 x #6 out of regulator to carb. Also, coil is very close to distributor, but consequently above the driver header (they're not coated). Therefore, everything is hot to the touch. 6AL box is inside the car. Lastly, the car is still running lean(er) than normal.

I'm going to attack the fuel regulator. May look at the pump too. And give the carb a cleaning.