Need a carb Recommendation

[king67rsss]

I'm pretty much clueless as far as how to choose a carb and what model to get. The engine builder mentioned that he used a 700 Holley Double Pumper but I'm not sure that is the right carb for a non- raced, weekend driver.
Here is my combo:
Pontiac 400 .030 over
Cast Crank .010 mains/.010 rods
Speed pro forged pistons
Cam- Ram Air IV with 1.5 rockers
Intake Dur. 308 -open 42-close 86 -lift .469
Exhaust Dur. 320- open 95- close 45 - lift .469- overlap 87
Heads- #15 castings 9.0 to 1 on 400 Pontiac
Intake- Edelbrock Pontiac Torker II

400 trans with 3.73 gears in a 8.5 rear

[6'9"Witha69]

The 700 size sounds good but I think for drivability a Vac Secondary would be better.

[king67rsss]

doesn't the Holley Double Pumper come with Mechanical secondaries?

[6'9"Witha69]

doesn't the Holley Double Pumper come with Mechanical secondaries?

Yes, double pumper is the nickname given to a Mech Secondary carb due to the 2 accelerator pumps (primary and secondary).

[king67rsss]

Looking through Jegs and Summit, I don't see any 700 carbs that have vac secondaries. Could you point me in the right direction?
thanks

[Shaker455]

King,
I build custom carbs and I have a 71 T/A 455HO

What are you running for a stall converter?

Considering your running an open plenum T2 intake I'd recomend a 4- hole spacer and a double pumper, 4 corner idle mech sec 750 as a vac sec carb will not feed your engine as well as a 4-corner unit with with an open plenum.

Also I can build you a nice HP style 750 dialed into you engines requirements.

[dhardison]

The holley web site has an interactive carb selector (top right corner of the main page). Never tried it but it can't hurt to enter your info and see what comes out the other end. If you do, please post the selector's recommendation. I'm curious to see what it recommends for your configuration.

http://www.holley.com/

[king67rsss]

Thanks Dan, The Holley site recommended the following:

0-80508S 750 CFM Four Barrel Street Carburetor 750 CFM Four Barrel Street Carburetor
Electric Choke; Vacuum Secondary, Model 4160
OR
0-80770 770 CFM Four Barrel Carburetor 770 CFM Four Barrel Carburetor
Electric Choke; Vacuum Secondary Street Ready out of the box; Two adjustments and go

[Shaker455]

King,
You got mail

[68Formula]

Thanks Dan, The Holley site recommended the following:

0-80508S 750 CFM Four Barrel Street Carburetor 750 CFM Four Barrel Street Carburetor
Electric Choke; Vacuum Secondary, Model 4160
OR
0-80770 770 CFM Four Barrel Carburetor 770 CFM Four Barrel Carburetor
Electric Choke; Vacuum Secondary Street Ready out of the box; Two adjustments and go

Had I seen your thread earlier, I would've recommended these as well. I like vacuum secondaries for mostly street driven too.

[Tom Welch]

HAve you considered a custom Q-jet? Cliff Ruggles can build you an excellent unit. He's on the net. First class work.

[Roger Poirier]

King,
I build custom carbs and I have a 71 T/A 455HO

What are you running for a stall converter?

Considering your running an open plenum T2 intake I'd recomend a 4- hole spacer and a double pumper, 4 corner idle mech sec 750 as a vac sec carb will not feed your engine as well as a 4-corner unit with with an open plenum.

Also I can build you a nice HP style 750 dialed into you engines requirements.

My own experience, less is better for a Pontiac engine. 750 cfm is more than enough. Chances are your going to have to have the carb re-jetted along with other small changes. I have a 428, 60 over with Ram Air IV heads. My carb is a Barry Grant 750 cfm DP. They had to downsize my jets along with other changes. Getting that carb tuned is critical to getting a Pontiac to run properly. Go with somebody that knows what they are doing.

R.P.

[Roger Poirier]

King,
I build custom carbs and I have a 71 T/A 455HO

What are you running for a stall converter?

Considering your running an open plenum T2 intake I'd recomend a 4- hole spacer and a double pumper, 4 corner idle mech sec 750 as a vac sec carb will not feed your engine as well as a 4-corner unit with with an open plenum.

Also I can build you a nice HP style 750 dialed into you engines requirements.

My own experience, less is better for a Pontiac engine. 750 cfm is more than enough. Chances are your going to have to have the carb re-jetted along with other small changes. I have a 428, 60 over with Ram Air IV heads. My carb is a Barry Grant 750 cfm DP. They had to downsize my jets along with other changes. Getting that carb tuned is critical to getting a Pontiac to run properly. Go with somebody that knows what they are doing.

R.P.

[Shaker455]

My own experience, less is better for a Pontiac engine. 750 cfm is more than enough. Chances are your going to have to have the carb re-jetted along with other small changes. I have a 428, 60 over with Ram Air IV heads. My carb is a Barry Grant 750 cfm DP. They had to downsize my jets along with other changes. Getting that carb tuned is critical to getting a Pontiac to run properly. Go with somebody that knows what they are doing.

R.P.

Roger,
I've been into Pontiacs all my life and been building carbs for Pontiacs for years as well as tuning, a well built 750 will feed his engine perfectly and I have done so with other 400's with great results.

A 750 is the standard size for most Qjets fitted on these engines stock so I'm not sure what experience you have if I read your responce correctly..... you sent your 750 back to BG to have them simply change jet size??

[Roger Poirier]

Roger,
I've been into Pontiacs all my life and been building carbs for Pontiacs for years as well as tuning, a well built 750 will feed his engine perfectly.

Also a 750 is the standard size for most Qjets so I'm not sure what experance you have?...I do like your combo though!

I'm agreeing with you. You put an 850 on a street 400 Pontiac and it will run very, very rich. I know from my own experience. Purchasing out of the box will get you started, however changes always have to be made.

R.P.

[Shaker455]

I'm sorry Roger as I said I must have not read your post correctly.

Tell me more about your combo?

My friend out here Lenny Caverly who competes in Enginemasters has a 458 Pontiac that he runs on the street/strip: 428 block, 455 crank, BME alum rods,flat tops,RAIV heads ported, 11.4:1 custom solid roller he designed to run on pump gas....runs awsome and does 11's

[Zee]

King, Let Shaker build a carb for you. You won't be dissapointed.

[Roger Poirier]

I'm sorry Roger as I said I must have not read your post correctly.

Tell me more about your combo?

My friend out here Lenny Caverly who competes in Enginemasters has a 458 Pontiac that he runs on the street/strip: 428 block, 455 crank, BME alum rods,flat tops,RAIV heads ported, 11.4:1 custom solid roller he designed to run on pump gas....runs awsome and does 11's

King67RSSS, this may help you in your next build process. Or maybe not?

I had a Ram Air III 400. There just was not enough power for me. I went to the big guns, however still wanted to stay with a Pontiac engine. This is before stroker engines became popular.

428 4 Bolt Mains - Bored .60 over
Ported and Polished Ram Air IV Heads (milled aprox .020)
Forged Rotating Assembly
Edelbrock Torker Manifold, Ported and Polished 1" Spacer
Barry Grant 750 DP
MSD Ignition
Hyd Ram Air IV Cam 1.65 Rockers (Close to those specs.)
2" Hooker Custom Headers with X-pipe and 2 1/2" in exhaust.
4.10 Rear Gear
TKO 5 Speed

R.P.

[Tom Welch]

For Pontiac guys, Jim Hand is considered an expert on tuning and building for performance. Cliff Ruggles is the same in this respect. Jim Lehart is also very well respected in the Pontiac community. All of these guys would probably recommend a well built and tuned Q-jet for a Pontiac engine that will see street driving. All of these men can be corresponded with on the Pontiac Street Performance website. Jim Hand and Cliff Ruggles have authored books on this very subject. Both are very valuable for us Pontiac peeps.

[pitts64]

Cliffs custom Quadrajets are well proven.
I have one on my 462 and it runs great.
http://www.cliffshighperformance.com/

IMO you have too much cam for a 9 to 1 400. I would try a Crower 60916 or at least add Rhoads lifters to the ra-4.