Carb selection question

[Ohio Rob]

Hello all. I have a 446 CI big block Mopar in a 4 speed Coronet. I have a 3.73 gear with a 28” tall tire on the car. Car weighs around 3600
The engine is:
-9.5:1 compression
-Holley Street Dominator intake blended to the heads and cleaned up a bit.
-Pertronix ignition 20° base, 34° all in. (All in by 2500 or so)
-Ported 906 iron heads that flow 295 on the intake. 2.14” valve
-Cam is 234°, 240° @ .050 .530" lift on a 109° LSA.
-Vacuum in 10” to 12” at idle
-1-7/8” headers


I use the car as a hot rod street car with an occasional trip to the strip. I don’t drive it in the cold weather and I don’t drive it for commuting.

I’m considering an HP 80511-1, 830 CFM with annular boosters.
The intake heat crossover is blocked.
I thought the annular boosters would help the low end and the 830 would still give me good top end. Does that sound like a good choice? Thanks.

[econo racer]

I think it would run fine

[BradH]

I suspect from a previous time working on someone else's 830 annular that the out-of-the-box tune for it could be pretty far off for what you've described.

You don't have killer compression or cam, so the RPM range w/ your combo is probably about "done" by 6200. A smaller venturi downleg config with a better venturi-to-throttle bore ratio will probably be easer to get set up, drive cleaner on the street, and make about the same power given the rest of your combination.

You'd get really good throttle response w/ something having a 1.38" to 1.40" venturi; a 1.42" to 1.45" venturi config would still drive well and maybe 5 - 10 HP more (smallest to biggest variation).

Naturally, just my $.02... but it's based on my experiences with 440-ish street/strip BB Mopars over the years.

[1980RS]

I have both the 830 and the 100hp with A/D booster. The carbs both ran well but were jetted to lean out of the box. I now an using some older Demon A/D carbs and all 4 of them work great and buck easier to tune IMO. A/D boosters really help out my 60ft times.

[F-BIRD'88]

Its the intake not the carb.

[BradH]

Its the intake not the carb.

The Holley Street Dominator for a BB Mopar is a low-rise single plane w/ relatively small runners. I see nothing wrong w/ that choice of intake, although a Performer RPM might be better in the torque department and make comparable HP.

[F-BIRD'88]

Brad these intakes have no bottom end and no top end.
The whole series are duds.

[Ohio Rob]

The intake has to fit under a stock hood.

This isn’t a max effort deal, by any means.

What series of Holley (I want a dichromate finish, traditional type carb) would provide the Venturi size and ratio you are suggesting Brad? I believe the 830 HP with down leg boosters has a Venturi size on 1.56

[F-BIRD'88]

Its a old Coronet not a vette. It will take a high rise intake with correct aircleaner. The Edelbrock Perf RPM 440 intake is the best single 4 bbl intake for your car
. Especially with a generous carb. Time to move out of the '70's. All the low rise single planes are bad for your car setup.. The cam installed phasing should be checked.

For the RPM range you use you want it advanced VS "straight up".

[Ohio Rob]

Here’s where the cam is installed:

[Ohio Rob]

Also, the car will not take a taller intake with the stock hood and stock air cleaner. I’m not willing to change that stuff, so a low rise intake is it.

I’m trying to make the best carb selection, within the parameters I have set.

[F-BIRD'88]

The rpm intake is only .66" taller in the middle. You just need to modify the base of a stock aircleaner for a deeper drop.. It will make a ton more low end torque and more power too.
Your car needs a dual plane intake manifold.

[BradH]

The intake has to fit under a stock hood.

This isn’t a max effort deal, by any means.

What series of Holley (I want a dichromate finish, traditional type carb) would provide the Venturi size and ratio you are suggesting Brad? I believe the 830 HP with down leg boosters has a Venturi size on 1.56

The original 80496 has a 1.38" venturi and 1.75" throttle bore. I have no idea what the tune from Holley is these days, but the one I ran 20 years ago was a bit fat down low and could have used some "refinement" for street use.

This is an old Braswell version of the 80496, FWIW. Holley sells their factory refurb 80496s for about $550 if they are still available. It's seriously old school with cast metering blocks and base plate.

[hysteric]

With the spread bore manifold why not try a 850 Thermoquad?

[Geoff2]

Yes, 850 Mopar Thermoquad. And when someone asks why you aren't using a Holley, you can say what my mate says: [ he runs a 850 TQ on a 455 Pontiac ], ' Because I want to run faster...'