Vintage Mustang Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
17 Posts
Discussion Starter #1
Does anyone know if when I upgraded to a 4 barrell carb if I need to get a high volume fuel pump. My engine does not want to stay running. It is being starved for gas. I need help. Thanks
 

·
Registered
Joined
·
491 Posts
your fuel pump should be fine. it sounds like your mixture is just to lean. you need to ajust the mixture screws. that should fix it.unless your fuel pump is bad.
 

·
Registered
Joined
·
6,331 Posts
It should idle and run down the street the same as a 2 BBL carb . The only time it might starve is under a heavy foot and at speed . You need to be making some serious horse power for a regular pump to not be able to supply the carb .
If it's starving at idle you may need to adjust the float levels ... and thats about a guarantee on a Holley 4 BBL .
 

·
Registered
Joined
·
3,595 Posts
Is this a new carb out of the box? If not, what did it come off of? What engine do you have (hint: fill out your bio). As a matter of fact, what brand carb did you put on the mystery motor.

Very few carbs come out of the box correctly set up for the engine you buy it for, at least none of mine ever did. Have you adjusted the idle air mixture screws to obtain as good an idle as possible?

A rich mixture will run just a bad as a lean mixture. Holleys are very adjustable carbs. I suggest you get a Holley book if you are going to own and adjust on one. After you get the engine idling OK, take it out and give the engine a good run at highway speeds. Take it home and shut it down immediately and pull the spark plugs to get a "read" on whether the mixture is lean, rich, or right on. The way you adjust the richness of your mixture is to take it apart and change out jets. The idle mixture screws are just that, for idle only.

A little more info will help us give you guidance.
 

·
Registered
Joined
·
50 Posts
Old school problems.... Did you take the fuel pump out? It has been know to have the spring fall out of the pump. Did you put the pump lever in properly? It should be on the underside of the lobe. If this is ok do you have an inline filter? If so, is it directional? Did you remove the distributor? Did you put it back in properly? Timing might be off. Do you have a new gasket on the carb? Maybe you are getting an air leak. Do a O2 test for this. I wouldn't dismiss the carb, but I would double check everything before messing with the floats. I believe newer Holleys require your to dril out the air settings, because they are factory set. Go to the holley web page and read up on it. If you isolate it to the carb, buy an Edelbrock. Problem solved. LOL! ::
 

·
Registered
Joined
·
2,614 Posts
if you want something that doesnt require alot of tuning, and man hours to make it run perfect, id suggest an edelbrock, often times right out of the box they run well. if you want more tuneability and a way to eek out some extra power numbers go for the holley or maybe even a demon , which is a holley in a halloween costume according to some.
 
1 - 6 of 6 Posts
Top