30 Zenith Carb

[William Kelchner]

My 30 appears to have a carb problem. Idles great but put it under load and it starts coughing back through the carb. Forum member and I think it is acting like a float problem. Has good fuel flow. No starting probs, no overheating issues. Tried numerous GAV settings all to no avail. I have read that a sticky/hung float can exhibit symptoms like this. Now to the point I could not make it 1/8th of a mile back to the driveway this morning . Thanks

[700rpm]

If this just started, I would suspect it's not the carb. My first thought is condenser.

[Mitch//pa]

Are the points gapped ok

[kenparker]

In the model A world 85% of the carburetor problems are electrically generated.

[William Kelchner]

Originally Posted by kenparker

In the model A world 85% of the carburetor problems are electrically generated.

Yep it is a constant problem and prevents me from even attempting to venture out with the car. Love the quote. One thing that stumps me is the car will idle great, rev the he$$ out of it and it is flawless, but don't try to drive it. Oh well - thanks for the responses. Have a good weekend.

[txkhog]

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also check your coils, plugs inside cap. when there is a load on the engine it takes more spark energy to fire the plug and the spark may be finding an easier path to ground than across the plug gap.

[mrraford]

Couple of thoughts here:
you may want to check to make sure the jets are not clogged in the carb.
condenser could be the answer.
is it timed correctly? Is the timing advance working properly?
make sure your distributor and coil are working properly. ie point gap, timing setting, good coil, good condenser.
We would like to hear the ultimate answer here. Please report back.

[diomed]

I've heard of this happening with bad muffler. A baffle collapses inside and restricts the exhaust flow. It'll start and rev in neutral just fine. Once you put it under a load it has no power. It's very rare but sometimes it happens.

Originally Posted by William Kelchner

...One thing that stumps me is the car will idle great, rev the he$$ out of it and it is flawless, but don't try to drive it. Oh well - thanks for the responses. Have a good weekend.

[saintjoelarry]

Originally Posted by kenparker

In the model A world 85% of the carburetor problems are electrically generated.

Originally Posted by 700rpm

If this just started, I would suspect it's not the carb. My first thought is condenser.

First, glad you found the problem. It sure can be frustrating when you're looking for the solution, but it sure is rewarding when you find it.

I couldn't agree more with these two gentleman.

My model A was running very rich. I kept adjusting the float until I could barely get any gas flow, yet the exhaust still smelled rich. I replaced the jet cap with the smallest I could find. Still ran rich.

I checked the timing a few times, each time confirmed it was correct.

Finally, when I was checking the timing once, when I rotated the cam nut to open the points, I did not get a spark. I tried again and got a spark. I did this about 20 times, and got a spark probably 80% of the time, but not every time. I checked and found some carbon build up on the points. Filed them down a bit, checked the gap, and presto. Runs perfectly.

So as you say, my "carburetor problem" was electrical.

[30ccpickup]

Backfiring Under Load (throttle wide open at relatively low rpm’s) often indicates a problem in electrical/ignition/timing.

Culprits include:

Insufficient point gap (should be set at .018 to .020)
Timing
Bad condenser
Bad distributor body
Frayed wire between upper plate and lower plate on the distributor
Intermittent connection of the ignition switch

As Mitch said I, would start with point gap.

[William Kelchner]

Ok you guys thanks. I shall go through everything over the weekend, saving the carb for last, hopefully the culprit will be identified. I replaced the dist with an original type from Bratton's, the Zenith was also purchased from them, all this about 2 years ago. I also replaced the timing gear around that time.

I shall report back. Thanks again.

[Quigley1930]

Bill, I'll meet you in Marshall at the Ford dealer and we will get 'er done

Sewall

[William Kelchner]

Thanks Quigly, I can always count on you

[William Kelchner]

Well installed new points (orig style), the others did not look well and seen better days. Re-timed, checked spark (Tesla would be proud) Tried to make it around the block, almost made it but coughed several times. Carb tomorrow, another trip around the block. If no better there will be a lot more room in the garage. Have a good weekend.....

Bill K

[Tom Wesenberg]

Never give up..................it's such a good feeling when you find the problem.

[700rpm]

Condenser.

[William Kelchner]

Originally Posted by 700rpm

Condenser.

I have a "burn-out Proof" condenser, so the catalogue said. I replaced my dist several years ago with a rebuilt one from Brattons, it had the cap installed. Tnx

[700rpm]

I refer you back to posts #2 & #15.

[William Kelchner]

Originally Posted by 700rpm

I refer you back to posts #2 & #15.

Yes I was about to PM you on this very issue as you seemed convinced it was condenser related My hat is off to you sir....Cheers

Bill K

[700rpm]

Originally Posted by William Kelchner

Yes I was about to PM you on this very issue as you seemed convinced it was condenser related My hat is off to you sir....Cheers

Bill K

Just glad you got it fixed, Bill. We want our cars running for the summer!