Hi guys,

I need to get this carb setup to this motor. Its a 750 dp w/secondaries PV blocked.

I hooked up a vaccum guage inline w/the distrib. advance hose. Cruising is around 16-18 inches. Moderate acceleration, the guage doesn't go below 10". Only under full throttle conditions does the needle go below 10". Its amazing how the vaccum changes so frequently (gear changes, throttle, etc.).

Engine is a 454HO btw

Thanks!

BTW there is a 4.5 in there now. That was probably for the 284/.544 Crane-cammed 396 that was in there previously.

As a start, I'd put a 9.5 in there - it will keep you out of it unless you're at or near full throttle.

To really nail your settings down, take it to a dyno shop and have them tune it on the dyno. WELL worth the money to have it at the best match for your combo, IMO.

Agree with the 095 or even a 085.

FROM THE 2000 HOLLEY CATALOG

A COMPETITION OR RACE ENGINE WHICH HAS A LONG DURATION, HIGH OVERLAP CAM WILL HAVE LOW MANIFOLD VACUUM AT IDLE SPEEDS. IF THE VEHICLE HAS A MANUAL TRANSMISSION, TAKE THE VACUUM READING WITH THE ENGINE THOROUGHLY WARMED UPAT IDLE. IF THE VEHICLE HAS AN AUTOMATIC TRANSMISSION, TAKE THE VACUUM READING WITH THE ENGINE THOROUGHLY WARMED UP AND IDLING IN GEAR. IN EITHER CASE, THE POWER VALVE SHOULD HAVE AN OPENING POINT ABOUT 2” HG BELOW THE LOWEST INTAKE MANIFOLD VACUUM READING TAKEN.

A STOCK ENGINE, OR ONE THAT IS ONLY MILDLY BUILT FOR STREET USE, WILL HAVE HIGH MANIFOLD VACUUM (17” TO 21” HG) AT IDLE SPEEDS. TO DETERMINE THE CORRECT POWER VAVLE, THE VEHICLE SHOULD BE DRIVEN AT VARIOUS STEADY SPEEDS AND VACUUM READINGS TAKEN. THE POWER VALVE SELECTED SHOULD HAVE AN OPENING POINT ABOUT 2” BELOW THE LOWEST STEADY SPEED ENGINE VACUUM OBSERVED. HOLLEY HAS A 6.5” HG POWER VALVE P/N 125-65, WHICH USAUALLY WORKS OUT WELL FOR MOST DRIVING SITUATIONS.

HOLLEY MAKES STANDARD POWER VALVES IN THESE RATINGS…
1.0”, 2.5”, 3.5”, 4.5”, 5.5”, 6.5”, 7.5” 8.5” 9.5”, 10.5”.

THE HIGH FLOW UNITS ARE AVAILABLE IN THESE RATINGS..
2.5”, 3.5”, 4.5”, 5.5”, 6.5”, 8.5” 10.5”

THERE ARE ALSO TWO STAGE POWER VALVES AVAILABLE BUT THEY ARE NOT RECCOMMENDED FOR PERFORMANCE APPLICATIONS.

Vince,

I have a 6.5 in my 770 Vac Sec Holley.