Electrical Issue?

[Duffman]

Carbs are definitely in need of a rebuild, with the throttle shafts allowing more of a leak than I would like. I have applied one of Blue's ideas and capped the end of the throttle shafts to minimize the leak. I know the floats are set correctly and have adjusted the mixture to make sure it is not too lean. Appreciate the thoughts, Pete!

[Duffman]

UPDATE: Borrowed a set of carbs from a buddy, installed new plugs, fuel filter, distributor cap and rotor, fuel pressure gauge and adjusted timing to 10 degrees BTDC. Balanced carbs and set idle to a very nice 900 rpms (as low as I have had it in years!). Fuel pressure a constant 3.5 psi on mechanical fuel pump. Idles like a champ, not cutting out anymore. However, under load I seem to find the engine "diesels", or chugs, when warmed up. I have pulled on the choke to see if it is running lean and it does not improve.

So, have corrected a long-term idle issue with replacement carbs, but still have an on-the-road issue with the car dieseling/chugging/lugging while on the road and accelerating. Definitely worse when car is fully warmed up. I have not done anything major to the car which would have caused this, other than play with the carbs. I don't think it is fuel or carb related because everything is measured correctly and had the same dieseling problem with old carbs. Any thoughts?

Edited September 15, 2011 by duffman

[LeonV]

The term "dieseling" means that the car continues to run, after the ignition has been shut off. I don't think that's what you're describing. If the engine is "lugging" then downshift, you're in the wrong gear for the given load.

We need a better description of what is happening when you drive the car. What does it do at steady-state cruise (surging, bucking, etc.)? What does it do when you stomp on the pedal (buck, stall, etc.)?

Also, do you have a heat shield installed between the exhaust and carbs?

[Duffman]

Leon, when at steady driving (no acceleration), it runs fine. When accelerating, it starts out fine then starts to miss and it makes a chugging sound. Also, hear valves pinging. I did find a problem with my front carb float valve was sticking, bowl not filling, replaced it and idle still good, but acceleration problem still exists.

Yes, have heat shield between exhaust and carbs.

[LeonV]

If you floor it, will it hesitate then go, or will it completely bog and not pick back up?

Did you check the float level?

Drive around with a fuel pressure gauge taped to the windshield. Pressure can be okay at idle, but not with load.

[Duffman]

When I floored it, the engine bogs down/misses and lightly pings, does not pick back up. Checked both float levels, adjusted/synced as well as all other aspects of carbs. Fuel pressure has been consistent with idle and when engine revved or held at high rpms. Played with choke while driving and didn't help the situation by pulling on it to different levels.

Could I have any issues with my distributor causing everything to be out of balance?

Edited September 16, 2011 by duffman

[ConchZ]

Sounds like a fuel problem to me. Float valve partially clogged up? I had this happen to me the other way, where the float valve stuck completely open and gas went out the overflow. Smacked the bowl with a screwdriver handle and it cured it. Got the car home and took off the float. Something really small fell out of the valve and the problem was solved. Anyway, there's a screen in there that could be clogged up. If you haven't already checked it, make sure its clear.

[Duffman]

Removed the banjo screens in each float bowl already, as they were torn. I had issues with the front carb float bowl valve sticking, but replaced it. Adjusted the floats and checked fuel levels in each when I completed my test drives, both level.

[Randalla]

Steven, I'll be really surprised at this point if the problem turns out to be fuel, in light of all we've done and what we have eliminated. I'm feeling much more confident we have an electrical/ignition issue that shows itself only when the engine is under load. Still wondering if a faulty voltage regulator might cause this condition. I don't know, however, if the VR changes under load. Maybe someone else can comment. If the VR is not the culprit I think Doc needs to do his thing on your distributor.

[EScanlon]

At a WAG, check the vacuum advance mechanism, specifically the ball-bearing plate underneath the points plate (I know this is an electronic dizzy, it STILL has the mechanical advance system inside).

Second, from other posts on the site, most everyone has better luck with the E-12-80 Dizzy and the STOCK coil and the ballast resistor in the wiring. Your research may say otherwise.

The bogging under when accelerating and not "catching back up" is a good indication that the timing / fuel mixture aren't synched.

Try that and see.

E

[Duffman]

Randy, I have a newer alternator with internal regulator versus the old style external regulator. Not sure if that might be it, but is possible.

Interesting point, Enrique, I have checked the vacuum advance and it seems to work, but have received advice that it could still be the advance that is screwing things up. Have someone looking at the distributor this weekend to determine if that is the problem, will let you know!

[LeonV]

As a quick check, when this happens, spray the coil with freeze spray (or something similar) to quickly cool the component. If there is no effect, do the same for the ignition module. The point is if there is a heat-related failure with one of these components, this will diagnose it.

Have you tried this yet?