4bbl carb jet size question
 

Hi guys,

Im having some issues with my new engine setup especially the carburetor at least this is where I want to start. I dont even know if my question can be answered caus Im still new a this but Ive been driving with a car that smells like un burnt fuel for the past 2 years, trying different carb, jets, spark plugs, new MSD distributor,fuel pump, you name it I have changed it (following my friends advice) Still, we havent been able to make the car run so that I dont have to throw my clothes in the laundry every time I return from a drive. Exhaust is BAD, my eyes tear up when I step out of the car after backing it up in the garage so concentrated the smell is.

First question is, do you think a double pump 600 cfm is just too much fuel for a modified 289 thats used for casual street driving with the occasional hard acceleration? Second, is there a recommended jet nozzle size for this size of carburetor with this engine size? Not sure what other info would help, but Im getting desperate as I spend more time fiddling with this engine, than driving it and its getting upsetting at times.
Thanks in advance!

Do you have the option to switch from a dbl pump to a vacuum secondary carb? The 600 cfm size is reasonable, but the dbl pump portion is what is causing most of your issues.

Yes absolutely, I currently have both options and the newer carb has a vaccum secondary. Its on the car right now and producing some nasty exhaust smell but we installed it to get rid of the old double pump and we didnt really change or tune anything besides the throttle response screw on it.

This for sure. Unless it's a stick car with a bunch of rear gear that you're trying to get max performance out of, you don't need a "puddle dumper" carb. A 600 cfm vacuum secondary carb will be much more suitable for mild combo in a casual driver.

What is the Holley list # on the vac sec carb you've installed? Read that off the choke horn, then you can look up the jet sizes on the Holley site to get an idea of it has if you know the carb hasn't been apart.


cheers
Ed