New Carb running bad

[snafu1]

Hello, I need some help with my 1960 Truck. It has a 235 with 3,000 miles on a rebuild. Just a few weeks ago the 1bbl Carb started acting up, like it was not getting gas an engine would die on me. Rebuilt the carb and still was giving me problems, so I got a rebuilt one from Summit. This new one runs like crap, unless the choke is half way closed, then it runs great! I checked all adjustments. Is this a vacuum leak? Carb is messed up? I also found the second exhaust port gasket is leaking on the motor. Is there a really good way to seal this? Better gaskets? Why would it leak so soon with a new motor? Any help would be great.... I am just not sure what else to do?
Thanks,
snafu1

[jayoldschool]

Have you tuned the new carb? Set the idle and mixture? Choke half closed, runs well tells me that it is running lean (with the choke wide open).

[snafu1]

Yes, I have. I thought it was running rich, that's why it ran better with the choke closed? I backed the mixture screw out for maximum richness, runs worse! Turn it in an then runs better, but only when the choke is half closed. Making me crazy! At least it runs, with the old carb I couldn't even get it to idle anymore, that's why I went with a rebuilt one. The idle I had maxed out to make it run, close the choke and idle goes up so I turn it back down. The old carb ran great, why it started acting up, I have no idea. The whole thing has been really sweet until this carb problem!

[66Submarine]

Originally Posted by snafu1

Yes, I have. I thought it was running rich, that's why it ran better with the choke closed? I backed the mixture screw out for maximum richness, runs worse! Turn it in an then runs better, but only when the choke is half closed. Making me crazy! At least it runs, with the old carb I couldn't even get it to idle anymore, that's why I went with a rebuilt one. The idle I had maxed out to make it run, close the choke and idle goes up so I turn it back down. The old carb ran great, why it started acting up, I have no idea. The whole thing has been really sweet until this carb problem!

The choke richens the mixture by restricting airflow.

Sounds like you may have a vacuum leak; check it out and see. Could just be bad installation, or a warped/misaligned manifold causing the intake/exhaust gasket to leak.

[66Submarine]

It goes without saying that you've also checked the ignition out, right?

[jayoldschool]

Turning screws is not tuning. You need to get a vacuum gauge on it, a tach, a dwell meter, and properly tune it. Fresh plugs, gapped correctly, fresh points, set dwell, set timing... it all needs to be done along with the carb adjustments. Of course, if you've already done all this... let us know.

[Dans66Chevy]

I think you answered your own question. You have a huge vacum leak at the manifold. I would bet money you spray some brake clean or something around the intake and it will pick right up and run. The other thing I would check is the sock on the fuel pick-up. If that gets plugged it will not get fuel...

[snafu1]

Ok thank you for the input! Yes fuel pressure and pump are good. Ignition is an HEI set up, plugs, cap, rotor, wires and vacuum advance are good! They have only 3,000 miles on them. All the tune up things mentioned where done, everything running super sweet until the old carb started acting up. I will check for a vacuum leak, I did try an tighten some of the bolts and yes they where loose! Is there any gaskets that are better then the plain jane FelPro ones that come with the engine rebuild kit? Again thank you all for your help and input!
snafu1

[66Submarine]

Originally Posted by snafu1

I will check for a vacuum leak, I did try an tighten some of the bolts and yes they where loose! Is there any gaskets that are better then the plain jane FelPro ones that come with the engine rebuild kit?

Guessing you found your problem! Just replace the gasket with another one, install it correctly, and you should be good (if the manifold isn't warped or something).

[snafu1]

Ok Thank you all for the help, funny I tried the old carb just for grins. I cleaned it all out and it runs fine! I know the exhaust gasket is leaking, so i will change that. It seem \s the new carb was the real problem!