With no offense meant to anyone:

That carb, if properly rebuilt and properly adjusted, should be good for a QUARTER of a MILLION miles!

Rebuilt twice and problems???

Maybe the carb is not the issue!

Questions you need to have answers to:

(1) compression test
(2) has an electric fuel pump been installed
(3) has a pertronix conversion been installed
(4) has a complete ignition test (with scope) been done

Check this link: http://www.thecarburetorshop.com/Troubleshooting.htm#Fuelleak

And this one:
http://www.thecarburetorshop.com/Troubleshooting.htm#Hardstarthot

Starting without choke cold or hot (unless you live in Honolulu, San Diego, or Miami, etc.) is a sure sign that either the carb is WAY out of adjustment internally, or the rebuild didn't address the issues, or there is too much fuel pressure.

No carburetor (or efi for that matter) is going to work properly if not properly set up.

Get some answers, and give me a call. No charge for tech advice.

573-392-7378 (9-4 Mon-Tues central time).

Oh, and suggested list price for the new Zenith replacement is right at a thousand bucks. How are you going to feel when you buy one and have exactly the same problems? Of course, you might have a friend in the business. I don't have a current wholesale price list, but in 2006 (my latest wholesale list) the wholesale price was over $500.00. Betcha it hasn't gone down in the last 10 years! wink

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop