KC John

I read a post the other day that mentioned trailer-hitching and I believe I have that problem. It was mentioned by someone with a 1460 carb on a 383 and was told it was too small a carb for that engine.

Can someone tell me if there is a way to fix a trailer-hitching problem without replacing the carb? I want to eventually go with EFI, but I don't think it will be this year.

Frankie the Fink

The condition occurs because of either too much timing advance or too lean of a mixture....

So I'd check the timing first as that doesn't require buying parts. With the vacuum advance plugged max timing (initial plus centrifugal) should be about 36*; some cars will accept 38*. With vacuum advance added on at cruise the max should be about 48*; although some cars can run with as high as 52*.

A quick and dirty check is to run with the vacuum advance plugged at a steady cruise and see if you still have the condition.

MikeM

Fouled plugs and/or other ignition misfires can cause the same symptoms.

Frankie the Fink

That is true...

Duck916

I'll add that while the carb might be too small (I don't know if it is or isn't), that in itself won't cause trailer hitching.

As Frankie said, a lean condition can cause it. But too small a carb doesn't necessarily mean the mixture will be too lean. The carb might not flow enough air to meet the engine's potential, but it should be able to meter enough fuel to match the amount of air passing through the carb, even if that airflow is lower than optimal for the engine.

So, if a lean condition is causing the problem, you should be able to fix that without swapping the carb--just adjusting the jets, metering rods, etc.

Patrick03

The too small carb thing came up in one of my threads. It was suggested that 600 cfm would be too small for a 383 and I was thinking maybe that was leading to my lean condition. After thinking it through some more I realized that might only be the case at higher RPM, and even then, I think what would really happen is you'd just run out of air, but the AFR would probably still be what it should be. In any case, for my situation it turned out to be a big vacuum leak.

To the OP, like Frankie suggested, plug the vacuum advance hose going to the vacuum can. This will tell you if the trailer hitching is related to timing. If you still have it, then it could be a lean condition (carb not tuned properly or vacuum leak), or the reasons that Mike provided.

KC John

Yes Patrick, your post is what has me asking this question. I'll plug the vacuum advance hose and see if it continues.