Holly Carb 4150/4160
 

I recently purchased an original (rebuilt motor, not carb) 67 FB 390 that was in Canada, I put 93 octane in it for the first time and the carb freaked out. First it would barely idle, ran it around the block and it somewhat cleared up. Now it is running really rich with some slight smoke from the exhaust. I have readjusted the float levels, the air/fuel mixture, and curb idle but it is still too rich. Prior to putting American fuel in it, the previous owner was using 94 octane and it ran beautiful. Something in the carb has popped, any ideas would be appreciated.

Runs really rough?
Loss of power too?
Smoke from both sides, or just one?
You didn't bend some pushrods did you?
You may want to check, I have seen this before... especially without lead additive.
It is easy to check the pushrods, just carefully pull em and roll them across a table. Your wifes $2200.00 dining room table will work fine. (if she's not home)

(or try a different carb for testing if you have one handy)
I do hope it is your carb though!

If it's the carb, it's probably the power valve. I doubt the gas had anything to do with it. If a holly has been dry for a long time, the secondary metering plate gasket could be a leaker. A common problem with our favorite cars is they sit so long that everything drys up. I'm also reminded that 50% of all carb problems lies in the ignition.