holley 670
You probably know this since you've been racing, I'm just getting into this and if I have it right, here is something guys might forget about.
Got this from Holley. SAYS:
Check your clearance at .015" at WOT.
And then it says Make sure that the accelerator pump arm is being acti-vated the moment that the throttle begins to move.
If you powerbrake, you may already be in your pump, so you need to back it off so you'll have more pump shot.
Also if your carb. is a street avenger, it could be 10% smaller than the advertised rating. Some Holley techs will tell you and some won't. So what do you believe. There are two ratings, wet and dry.
Forcedfed--Would like to hear more about you racing your vette buddy !
And thanks for the tip, OLDman RICK !
Hope this helps.
ACCELERATOR PUMP SYSTEM
The accelerator pump system consists of three main components:
the pump diaphragm, the pump cam and the pump nozzle.
This is the carburetor system that is most responsible for having
good, crisp, off-idle throttle response. Its purpose is to inject a
certain amount of fuel down the throttle bores when the throttle
is opened. By accomplishing this purpose it acts to smooth the
transition between the idle and main circuits so that no stumble,
hesitation or sluggishness will be evident during this transition
phase.
The first adjustment to check is the clearance between the pump
operating lever and the pump diaphragm covers arm, at wide
open throttle. This clearance should be around .015". The pur-
pose for this clearance is to assure that the pump diaphragm is
never stretched to its maximum limit at wide open throttle. This
will cause premature pump failure. Once this clearance has
been set take a good look at the pump linkage and work the
throttle. Make sure that the accelerator pump arm is being acti-
vated the moment that the throttle begins to move. This will
assure that pump response will be instantaneous to the move-
ment of the throttle. These adjustments can be made by turning
the accelerator pump adjusting screw that is located on the
accelerator pump arm together with the pump override spring
and lock nut.
The amount of fuel that can be delivered by one accelerator
pump stroke is determined by the pumps capacity and the pro-
file of the pump cam. The period of time that it will take for this
pre-determined amount of fuel to be delivered is affected by the
pump nozzle size.
