Holley 9379 on a street Car

[Horder]

Helping a good friend get a car running.

73 Nova
355 SBC, 11.5:1, 294 Duration, .540 lift hydraulic flat tappet
Single plane. Ported 186 Heads. Headers, 4 speed, 4.11 gear

All street car. Hasnt run in years and he bought a Holley 9379 for it. 750 Dp, annular booster, 4 corner carb. Called a competition carb. Has no choke plate etc. i have read that these are race oriented. I assume fatter idle circuit etc???

Any advice is appreciated

[Baprace]

That carb should work great in my opinion , BUT you must check fuel pressure , no more that 6 psi if higher then you need a regulator.

[Tuner]

Not sure about the idle circuit calibration, but the out of the box main jet sizes are 4 to 6 sizes too large. Best get a wide band O2 and tune it.

[Horder]

I haven't even opened it up see what the jetting is at. Holley shows similar primary jetting to a 4779 but a bit bigger secondary. 81 I believe.

Thanks for the replies…much appreciated

[Tuner]

The smaller jet requirement is because in this 1-3/8" venturi carb the annular booster occupies a greater percentage of venturi area, in comparison to larger venturi carbs, so the flow through the main venturi around the outside of the booster is somewhat restricted and flow through the booster is increased.

Of the total mass air flow, if that same mass of air was flowing through a carb with a larger main venturi, in this carb a greater percentage flows through the booster, resulting in higher velocity in the booster, which makes a stronger metering signal, and so does not need as large a jet to deliver the same mass of fuel flow.

Bonus of the higher velocity through the annular booster is vaporization is improved and less fuel mass can give the same A/F as a larger fuel mass because a larger percentage is vaporized and participates in combustion instead of making soot.

Ones of these carbs on a 495 cu.in. Olds in a Firebird I tuned in cool weather was happy with a 62 MJ. A 63 made it lazy. I didn't try a 61. It was a dual plane intake. I recommend using a WBO2.

[Horder]

Thanks Tuner! Always a pleasure to get your help and some of your knowledge.

[1980RS]

If he's going to drive it on the street just jet it down a couple of jets, should work great.

[bigcam406]

I had one years ago on a 355 small block with a stout solid cam (254 @ .050'' intake) paired with a Victor jr and a 1 inch tapered spacer. Stock jetting was 69 primaries, 84 secondary. Worked really well on the street, idled well. Only change i made was changing the power valve from a 65 to a 45. Other than that, just regular adjustments from time to time. Car went 11.60's with it on pump gas.

[Horder]

Well i opened the carb up today. Here is whats in it. Factory parts in ( )

Pri Main are 71 (68)
Sec Main are 76 (81)
Pri nozzle is a 31 (28)
Sec nozzle is a 25 (31)
Primary transfer slot was a bit long
Primary blades each have a 5/64 hole drilled. Almost looks original?? Any chance of that? Just looked up the part # and yes the 215 Blade has a hole pre drilled.
4.5 Power-valve in Primary (6.5)
Blank block off PV in secondary
Pri idle screws at 1.5
Secondary at 1.25

This 355 has small dome pistons
2.02/1.6 ported hump heads
244 @ .050 hydraulic flat tappet
Single plane
1 3/4 headers
Muncie 4 speed
4.11 gear
73 Nova street car