New carb and intake manifold

[USU_Stang]

I've got a 68 with a 289. Put an Edelbrock Performer 289 and Motorcraft 4300 carburetor on it and now we are having issues starting it. I can get the car to start and run at about 2000 RPM (estimate) or above, but when it drops below that for a second or more it dies. Friend I got the carb from had it on his Mustang about 6 months before now and it ran fine. We marked the distributor when we were taking it out, so timing SHOULD be fine. We have moved the distributor around a little bit and the car has gotten worse, but no better. First off, can someone tell me the initial setting I should use for the idle fuel mixture screws? With my old Autolite 2100 you would back the screws out 1.5 turns from all the way in. Other than that, anybody got ideas to try?

thanks
--Jason

 

[iskwezm]

did you check for vacume leaks?

 

[USU_Stang]

not entirely sure how to do that...i've heard vague references to using carb cleaner, but...

 

[rbohm]

i would ditch the 4300 and try and find a 4100 to replace it with. the 4300 is rather a piece of junk carb. that said, vacuum leaks are usually cause the problem you describe.

 

[USU_Stang]

Again, how does one check for vacuum leaks, especially if the car won't run?

--Jason

 

[iskwezm]

spray carb cleaner along the carb base and the intake rails where it meets the heads.If your idle smoothens out or raises you have a leak

also retorque the manifold just in case

 

[USU_Stang]

sorry, i'm still confused about how I am supposed to do this if the car won't idle...
I will retorque my manifold bolts though.

thanks
--Jason

 

[krash kendall]

First off, check the back of the carb for a 3/8 port at the base. If it is open plug it. It is a vacuum source for power brakes. Then check for minor vacuum leaks after you get it running.

 

[iskwezm]

raise the idle so it will at least sun and then spray for a leak,it ifs that bad where it wont run,its a pretty big problem.