quote:Originally posted by pantera74Bills6976:
When running my car on the highway at 55-75 car acts like it starving for fuel but hit the gas a little and no problem, I am running holly 650 on 351 c 1974 standard fuel pump . Do I need to adjust carb
In pantera74Bills6976 original quote he does not say it was running fine then went bad or lean or whatever, he states it feels lean crusing between 55mph and 75mph but when he opens the throttle it seems fine.
1. by 55 to 75 mph he should be on the beginning of the primary main jets at least.
Unless he has a diff ratio of 2.55 : 1, but i'm sure Pantera's are higher than that.
2. If it is lean on the primary mains, opening the throttle a bit will seem to fix things, because as you do this the manifold vacuum will drop and the primary power valve will open and allow greater fuel flow to the primary main system.
3. on a holley the primary jet also feeds the primary idle circuit. Even though there are independent idle jet restrictions (not replaceable jets) and idle air correction jets, the main jet does still effect the idle circuit.
4. From the picture of the engine supplied (if it is current) it does not look like it would be a 150,000 mile junker with a carb full of crud. That may be wrong and it is always worthwhile to clean the carb and check things out but i agree you should not go at it with a big hammer straight away.
5. Stay away from interfering with air bleeds unless you know "EXACTLY" what you are doing. They not only effect the richness of the circuit (idle or main) they also effect the "timing" of the circuit. You can wind up with one great big flat spot.
A blocked air bleed with make it richer, Very much richer..
6. if it is true that the car just seems to be a little lean and has always been this way as far as you know, just try slightly richer primary jets
Ps: always worthwhile to check the float level too !