[Skippy597]

Hey guys I'm putting together a dual quad on a 400 build. There is a matched pair of carter 9636s carbs for sale, are they a decent carb to run for a dual quad setup. I know they won't be as correct looking as some other choices but I think anything will be better than a new edelbrock.

Thoughts?

[Mike Davis]

Don't discount the Edelbrock carbs no matter what you hear. I have set up many for dual quad set ups and they work great with a little work.
What intake and the rest of the combo?

[Skippy597]

Still piecing it together but offy 5499, ported edelbrock heads, pontiac 400, planning a crower solid flat tappet cam like a 60310.

[tom s]

They should be fine as Mike said.Tom

[Mike Davis]

The 9636 are OK but I have found that they have a dirty/rich idle to them but can be made to work. All the 9000 series Carter Comp series use the same parts the later Edelbrock carbs do for the corresponding CFM rating.
If you are only looking for a cruiser and not concerned about performance the 65-66 (3896 & 4034) GTO carbs work well.
If you are looking for performance, with the cam you are looking at, have headers, converter or 4 spd and a 3.55+ gear etc, I would look at a pair of 750's. The older 4760 and 4762 work very well as do the later Carter Comp Series 9755S.
Very few on here like the 9XXX carbs like the 9755. I have 3 sets in use and they all work flawlessly for street strip use. My 66 with a set of Carter Comp 9755S with a 421, stock 4" stroke crank, Aluminum Heads etc made 790+HP with those carbs, runs 9.70's and is street driven a good bit locally in traffic etc.
The Edelbrock 1407 is the later version of that style and with a jet and metering rod change are not a bad choice.

The 5499's I have run like a small 1/2 spacer under the carb.

[25stevem]

With your 400 motor if you have not spent money yet on getting them ported then please keep those funds in your pocket or spend them else where on the motor or car where the money will help!
That Offy intake will barely support the air flow of those aftermarket heads in stock form, no less ported, not to mention you will be narrowing up on the motors torque band by having bigger area / higher flowing head ports trying to suck more air out of smaller / limited intake manifold runners and plenum.

On a 455 with a street/ strip car without great traction you can afford to give up some low and lower middle rpm torque, but on a 400 or less cid motor in my opinion you just can’t unless your running 3.90 rear gears !

Now what I have posted up will get challenged yet again by those saying there similar combo like what the Op is proposing runs great, and my reply is well if you did it right it would make even more power and in turn run even better, but these folks are into the eye candy part of it , which I guess is fine.

These folks have done no flow bench guided velocity study’s like I have with regards to both correct and non correct combo’s like this and are just speaking out there Butt hole for the sake of not having hurt feelings from spending money where they should not have.

[Skippy597]

Well I bought the heads used for a good price and if I can't get the intake to work maybe I'll go with the wenzler. I have been worried about the intake but damn it looks cool. But I am going to try my hand at port matching the intake and hopefully that will help. Should I be going with 750s or 625s?

[Skippy597]

Originally Posted by Mike Davis

The 9636 are OK but I have found that they have a dirty/rich idle to them but can be made to work. All the 9000 series Carter Comp series use the same parts the later Edelbrock carbs do for the corresponding CFM rating.
If you are only looking for a cruiser and not concerned about performance the 65-66 (3896 & 4034) GTO carbs work well.
If you are looking for performance, with the cam you are looking at, have headers, converter or 4 spd and a 3.55+ gear etc, I would look at a pair of 750's. The older 4760 and 4762 work very well as do the later Carter Comp Series 9755S.
Very few on here like the 9XXX carbs like the 9755. I have 3 sets in use and they all work flawlessly for street strip use. My 66 with a set of Carter Comp 9755S with a 421, stock 4" stroke crank, Aluminum Heads etc made 790+HP with those carbs, runs 9.70's and is street driven a good bit locally in traffic etc.
The Edelbrock 1407 is the later version of that style and with a jet and metering rod change are not a bad choice.

The 5499's I have run like a small 1/2 spacer under the carb.

Mike what intake are you running with that setup?

[tom s]

IMHO,if using AFBs and progressive linkage get the 750s as you will be driving on the front 2 bbls of the rear carb.That is how the factory ran the 421 SD 2-4s.Im diving one of my new repop Bathtub tunnel ram intakes with a pair of factory 750 NASCAR AFBs and drives great on the street.421 4 speed 62 GP.Tom

[Mike Davis]

Originally Posted by Skippy597

Mike what intake are you running with that setup?

I am running the Original Wenzler see signature.
I have run the 5499 on 400s, 428s. and 455s. It is a good intake. Not great but good. I ran one in the 90s on a .060 over 400, 265CFM #62 heads and a 255@.050 .550 cam. Car ran 11.00 and could drive anywhere. Changed to a Warrior Tunnel Ram and only picked up .15.
I have a new one that is port matched to a set of 305CFM speed master heads that will go on a 428 street build.
If you have it give it a try.
Larson and Garblik ran one on the Grocery Getter at one time.

Not sure who Steve was referring to.....

[Skippy597]

Originally Posted by Mike Davis

I am running the Original Wenzler see signature.
I have run the 5499 on 400s, 428s. and 455s. It is a good intake. Not great but good. I ran one in the 90s on a .060 over 400, 265CFM #62 heads and a 255@.050 .550 cam. Car ran 11.00 and could drive anywhere. Changed to a Warrior Tunnel Ram and only picked up .15.
I have a new one that is port matched to a set of 305CFM speed master heads that will go on a 428 street build.
If you have it give it a try.
Larson and Garblik ran one on the Grocery Getter at one time.

Not sure who Steve was referring to.....

Really like hearing that, thanks. I'll definitely put it together and see what happens. I'm putting this build together super cheap with used parts where I can. The heads popped up and were too good of a deal to pass up, I'll do my best to make it work.

[Skippy597]

There is a set of 9755s on ebay right now

[Skippy597]

Well that took a turn from how I started the post but I bought a set of nice 9755s for a good price. I'll try it and see.

[Cliff R]

I'm not overly fond of the Edelbrock AFB clones and have kicked a good many under the workbench over the years. In a single 4bbl application they can be difficult to make work well and some "cobbling" to make them fit like adapter plates and short spacers so the air cleaner base sits all the way down, plus cutting the factory fuel line and running rubber hose/clamps instead of a solid metal line up from the fuel pump.

When you get past all that they are super easy to work on and PLENTY of tuning parts out there. The weighted secondary air flaps can be a show-stopper with some set-ups. They fair a LOT better in dual quad applications, especially on cars with good power to weight ratios and plenty of gear/converter. I've seen many use them with good success and others work on them to the brink of extinction and end up moving on to something else, so for sure not a "home-run" with every application..........Cliff

[Mike Davis]

I think you will be happy with them. They also sell quick if you decide you don't like them.
Use the Ebrock kits for the 1407.

Nostalgia Super Stock guys have to run the AFB style carbs to be legal. There are guys running in the 9's and even a few have been in the high 8's with them.
They are much better in the dual quad set-ups than single.

[25stevem]

What I referring to here are the Dynamic tuning pulses that can be used to create more peak hp and torque if you use them right, or strip away hp and torque numbers that your motor could have.

There are 3 main harmonic pulses that can be used in achieving this.

The best one to use in non race motors is the 2nd harmonic pulse, as this works across the widest rpm band.

These results will tell you how long of a intake runner you need for a given amount of air flow and a given motor cid.

The runner length is viewed as being from the center rear of the intake valve to where the manifold runners end and the Plenum starts.

To get these results let’s assume that you have a set of heads that can flow 260 cfm@ 28”.

Here’s the results of running these numbers with 4 different cid motors, but with the same 260 cfm heads.
The formula I am using is for super stock motors so in the formula I am reducing the peak rpm part of the formula by 10%.

455 peak hp rpm 5428, intake runner length needed for this= 24 inches.

428 peak hp rpm 5735, intake runner length needed for this = 23 inches .

400 peak hp rpm 6138, intake runner length needed for this = 21 inches.

389 peak hp rpm 6314, intake runner length needed = 20.9 inches.

The intake port length on a Pontiac head is as in this example is 5.750”, the runner length in that Offy intake is no more then 4”, for a total of 9.750” which is far below what the formula’s I have posted up for peak hp across 10% wide rpm range from these results.

Now also consider the fact that in terms of peak torque using these runner length numbers generated will be , depending on the cam used 2000 to 2500 rpm less then these peak hp numbers posted here.

A street 389 with 260 cfm heads and the needed 20.9” long runners will make peak torque at anywhere from 3800 rpm to 4300 rpm, and this really needs to be taken into consideration when your over 10” short of the needed intake runner length as shown by these formulas.

[Stan Weiss]

This is an from a cam selection program I wrote with David Vizard where intake tract length is entered and you can enter 2, 3, or 4 and peak torque and peak HP RPM are calculated

"The 2nd reflection is the strongest, but may result in an RPM figure outside of the desired range. If so, try the 3rd or 4th reflection. Enter the number 2, 3 or 4. Shorter intakes usually work best with the 3rd or 4th reflection."

Stan

[Skippy597]

They were $400 for a really nice looking matched set so I feel that is a really reasonable price and worth a try. I'm gonna buy a carter/edelbrock tuning book as I am a holley guy. Does anyone have a recommendation for the best quality rebuild kits and a basic starting point for the tune up for them? I'm glad to hear they fair well for dual quad applications. I'm gonna try my best at porting the intake, I have a sacrificial intake that I can practice on first, I'm also gonna run 1" spacers on it to help a little.

I'm really sold on the dual quad setup, I just love the looks I know a single 4 barrel will probably be best but it's just not as cool. I'm going to try to run the 5499 the best I can but I'm really hoping I can find a nash/warrior (I believe that's what it's called) dual quad intake as I have read they perform better.

[carbking]

The 9755s was actually designed because of a 454 motorhome

Jon