carb size recommendations for dual quad 363 stroker

[F-BIRD'88]

Flatheadpopup: Re: the AVS carbs. The 800 cfm AFB and AVS carbs have a larger 1-3/4" throttles
so I do not believe that these will bolt onto the carb flange of your intake without
mod or a spacer.
The 650 AVS (thunder series) looks like a good carb for this 2x4 dual quad .
More powerfull than the 500's.

The 750 AFB and the 600 AFB will be more powerful too.

I agree with Tuner on looking for the manual choke versions of any all these carbs
for your dual quad. The auto choke version were set up/calibrated leaner in a attempt to be more mileage/emissions friendly.

You will need to dial in the primary jet and rods and secondary jetting on any choice.
Again the 750's will make the most power.
There are 1000's and 1000's of these in regular service including all the one's I had
that run fine and make great power.

It will run fine with the 500's but just not as powerfull as the larger 2x750 carbs will create.

You would like a 750 AFB #1407 on your vic JR too.
If you are willing you can go for the Eddy 302W Tunnel Ram w 2x750's
Thats my recomendation for your 2x750's (1407) on your cool RPM Dual Quad Dual plane.
Second choice the 650 AVS thunder carbs.

[Newold1]

Anybody try or run a set of 4224 Holley center squirters on one of these inline 2X4 intakes?

[Tuner]

F-Bird, seriously, have you ever used a WBO2 to see what the 750 Edelbrock does with the A/F as you move the throttle through the mid-range? It is lucky for these carburetors that gasoline has a wide range of flammability.

Do you have a 750 Edelbrock carb available to you to measure the location of the lower edge of the booster venturi relative to the minor diameter of the main venturi in the body casting? Measure that dimension and reply with what you find.

OP, a 409 Chevy does OK with a pair of 600s.

[Tuner]

Anybody try or run a set of 4224 Holley center squirters on one of these inline 2X4 intakes?

That would be a good setup, but I think the OPs manifold mounts the carbs too close together, otherwise he could use a pair of 1850 600 Holleys and have a sweet running deal for low bucks. Some Offenhauser 2x4 intakes space the carbs apart far enough for a pair of Holleys, some don't, not sure if the one for the OPs engine is like that. The SB Ford engines are short and there are distributor clearance issues (requires offset adapter drive, etc.) so probably not. There is a thread (are threads) in here by member "427dart" about his dual Holley 600 setup on his 427 Windsor using the PME dual quad intake for 351W.

[Newold1]

I was thinking cross mounted with some good linkage?

[F-BIRD'88]

F-Bird, seriously, have you ever used a WBO2 to see what the 750 Edelbrock does with the A/F as you move the throttle through the mid-range? It is lucky for these carburetors that gasoline has a wide range of flammability.

Do you have a 750 Edelbrock carb available to you to measure the location of the lower edge of the booster venturi relative to the minor diameter of the main venturi in the body casting? Measure that dimension and reply with what you find.

OP, a 409 Chevy does OK with a pair of 600s.

No I don;t have a wide band, but I do have a narrow band and use that to tune with.
I never had issues with the driveability of the 750 Edelbrock carb 1407 to really want to investigate this.
I believe you and are with you on the orientation of the pri booster cluster on the 750 carb but it is not such a big issue. The 750 carb works fine.

ALL carbs will show a bit of AFR change as you run at different throttle angles at part throttle. This is pretty normal stuff for carbs. The fuel distribution changes a bit
at different throttle angles at part throttle.
My 750's always ran good. In direct comparisons on my old 350 motor with vortecs and other SBC heads and also a few different intakes and cams, the 750 eddy always ran good,
My Holley 735VS (ford) also ran good. My custom made 750HP runs good too.
I tried a friends 600 EDDy carb too It ran good but not as good as the 750's.

The EDDY 750 1407 RAN the best MPH (1 MPH better) 1/4 mile repeadily on all those 350 motors.
The different ET's were so close as you'd have to call it a toss up on that car.
It made the MOST top end power on those motor.

I have never yet needed to go to a Wide band to tune with, I can tune carbs without a AFR gauge, But the NB I use is very usefull.
If I do run into a situation where I need a WB to get a good tune I have one available to me...

Like you said you seem to only see the FUBARED carbs that need fixing.

I do not have a 750 1407 eddy carb on hand right now to look, but I'm with you on it.
(I had a pair of 1407's but somebody wanted them and the cool tunnel ram a lot more than I did one day. $$$$$ made me give them up....)

The 750 1407 works good and works very well on Dual quad and street strip Tunnel ram
stuff. Very Near the same power as 2 good dialed in purpose holley carbs on a tunnel ram
and alot more "Driveable".
They have been shown to MAKE MORE power (over the 500's) on the RPM Dual Quad air gap manifolds and drive very nice too.
The odd design of the primary booster does not seem to be a big issue.
Back in the day Carter had different design and height boosters for their carbs that you could play with for effect.

I also believe that the 600's will also make more power than the 500's will.
They ALWAYS do.
The 650 AVS thunder carb looks like a good choice too.
If you want MORE POWER and want to match the power of the Vic JR on this Ford
with the RPM Dual QUAD use THE BIGGER carbs on it. The 2x 750's will make the MOST POWER especially if you step up the cam choice to get the best out of it.
The 2x 750's run great in Dual Quad and Tunnel ram applications.

Where guys run into trouble wit the eddy carbs is TOO MUCH fuel pressure
and Hot soak issues on some cars (a wood carb spacer helps a lot)
These carbs like mild 5-5.5 PSI fuel pressure but lots of Flow VOLUME on hungry HP motors.

A leaky primary booster cluster gasket will show that fault you describe.

When get another #1407 carb I'll look into what you have been posting on them.

[elmeano]

I would run 500's or 600's, i had a 750 never could get the throttle response down low like the 600's and I tried changing rods, jets, springs, etc. Granted, your application is automatic transmission and high stall converter, you might not notice the low rpm hole.. The 750 primarys are like OO compared to the 600's like oo. Have you seen the choke horn removal and smoothing modifications done to the afb style carbs? Worth googling, ive done it to a 600 and it seems to help.

[F-BIRD'88]

Tunner: One thing I did notice on a single plane intake the Holley carbs idle QUALITY is a bit better than with the Edelbrock carbs.
The reason is, Holley carbs idle on all 4 Barrels. (even the 2 corner idle carbs have 4 barrel pri and secondary idle circuits.

The Edelbrock 4 bbl carbs do not. They only idle on the primary barrels.
The secondary side does does not have a idle circuit. They only idle on the Primary front 2 barrels.
So naturally the idle quality is going to be a bit better with 4 active idle circuits.
(especialy once dialed in)

But the eddy carbs run fine. The 750 1407 is a good carb.

The 500's run fine but they are no ball of fire compared to the larger AFB carbs
on any capable motor. (400+HP) This includes both single and 2x4 applications.
The 2x500's are great for "out of the box" can't go wrong stuff on near stock motors (330+370HP)

OP: if you want to match or exceed the power of the mighty SBF Vic JR, then you want to step up the game with that cool RPM Dual Quad and give it all the carb(s) it wants.
This is the nature of Dual Plane hp intakes.
The dyno and street/track performance will show this.
You can end up with MORE POWER and MORE Torque and better overall drivabilty.

If you want to see for yourself before laying out the cash for 2 carbs, I recommend you beg borrow or steal a pair of the 1407 750's and DYNO TEST them.
(Be prepared to dial in the jets and rods to get it right)
Don;t be afraid to play with carb spacers too.
These 2x4 intakes always seem to like carb spacers.
The dyno will prove this. Road test with them too, if you can. The proof is on the pudding.

Then lay out the cash for the right 2 carbs.
I "been there done this" on this issue.

If you ask nice, Joe Sherman may offer some good advice on this.
He's been there on this with a few different 2x4 motors.

[F-BIRD'88]

Have you seen the choke horn removal and smoothing modifications done to the afb style carbs? Worth googling, ive done it to a 600 and it seems to help.

I have seen exactly what you are refering to on the AFB carbs. But have not yet had the chance to try it my self. Putting the smooth areodynamic over caps over the seconday counterweights seems very cool to clean things up for better air flow and quality.

Edelbrock should come out with a "VIC JR" (racer) billet CNC CkokeLESS carb top with these air flow improvements.
If I worked at Edelbrock, I'd be so annoying. HA HA.

[Flatheadpopup]

The intake I originally intended to run on the 363 and have sitting in the garage is a Super Victor (not the Jr) with a Holley HP so I'm pretty sure I stand to lose a few horses with any of the dual quad setups available short of a tunnel ram. I really don't want to cut up my new fiberglass hood so a tunnel ram is out, which limits me somewhat. As long as it doesn't give up more than 20 or so horsepower I'm good with it. Aesthetics do play a part in this build so it is what it is unfortunately. That said, I want as much power as I can get


I haven't purchased any of the dual quad components yet, but plan to in the next week. If anyone feels that there is a better intake than the Edelbrock Air Gap dual quad for what I am doing feel free to speak up. I'm not against using any of the old school stuff--I just haven't seen any that look like they flow enough air to make the power I'm looking at (admittedly, I could easily be missing something out there). Removing the choke horn from the afb doesn't sound like a bad idea, my last 3 Holleys were like that.

Tony

[F-BIRD'88]

Be aware that on these AFB carbs if when you do cut off the choke horn it will CHANGE how the carb works and how it meters fuel. Be prepared to rejet it. Be prepared to also
need to re tune the idle circuit (air bleeds etc).
It changes how the air goes into the carb and changes the fuel signal on these.
You also want a correct radiused carb base, not a flat base.
All this effects how the air goes in and how the fuel metering circuits reacts.
That means be prepared to re-tune the carb.

You can take the choke plate off with minor effect, but when you cut off the choke horn on a AFB carb things change.
Again, if you want more air flow BUY the BIGGER carb(s) to start with.

All the pretty show car 2x4 Dual Quad air cleaners for this SUCK.
You can build a much better 2x4 Dual Quad carb air Cleaner with a correct radiused drop base
that makes MORE power on the car.
Look at the 70's era 2x4 426 HEMI air cleaner for inspiration.
Thats a serious Dual Quad air cleaner. It matters. The details matter.

[F-BIRD'88]

On a street car you may appreciate having the chokes there.
For easy start up and better warm up. BUY the bigger carbs with manual chokes
and hook up a manual choke cable so you can use it on cold days.
The choke control cable goes on the rear primary carb.

[Flatheadpopup]

I searched high and low for an air cleaner that I like for Edelbrock setup and did not find one I liked. I had already contemplated having to modify something to fit that is more suitable-there is a lot more available for the standard Holley spacing .

As for removing the choke horn...seems like more work than its worth, at least for the time being. Maybe after I have everything sorted out and feel comfortable tuning the carbs I'll come back to the idea. Thanks again for the advice, its appreciated.

Tony

[F-BIRD'88]

If you make up your own proper Custom Made Drop base Dual Quad air cleaner base
that not only gives more under hood room, it also allows for a BIGGER air cleaner filter element and also ALLOWS ROOM for carb spacers for POWER.

You can probabily find a pretty air cleaner LID with the right spacing you like that works with it.
The contour of the base matters. The air cleaner matters. Final tuning must be done
with the air cleaner installed. It even effects the idle and off idle fuel metering.

Are you using a Cowl induction style hood on the Mustang?

[Flatheadpopup]

No, it has the 67 Shelby style scoop. I wanted the larger opening than what the 65-66 Shelby hood would have given me. I almost went with the cowl hood but I just knew that all my Bowtie friends would razz me relentlessly. I mocked it up with the Super Victor+1" spacer and air cleaner...had room to spare so I should be good, but who knows till I put it all together? If I need more room I'll subtly modify the opening to gain the clearance needed.