What would you do...?

wahoo23 · Mar 6, 2008

I recently cracked my intake manifold (long story, see other posts), and am in the process of shopping for a new manifold and carb. I see two options:

1) Buy a new Edelbrock air-gap manifold and new 600 or 650 carb.

*or*

2) Buy a new dual-quad manifold and add a second 500 Edelbrock carb (to match my existing 1403).

I'm already in the process of adding an MSD ignition, and will upgrade the fuel pump, as well.

Pros? Cons?

[This is a '67 with a 289/302]

woodsnake · Mar 6, 2008

Ya know, they now make an air gap dual quad intake. I'm going to swap mine out when I get home in June, I think. That's the plan any way!

How much cam have you got in it now? A single 650 on an air gap will run much better for you, unless you're into the throttle enough to use the 2X4's.

As far as the MSD goes, I'd suggest using a Ford Duraspark distributor, and an MSD 6A box. On a street motor, I don't think the expense is justified. I put the complete MSD(dist,box,wires,coil) in my 69, and the duraspark in my 68. For the money, Duraspark is the way to go.

mikethebike · Mar 7, 2008

If this is a street car just get an Edelbrock RPM with a 600 vacumn secondary Holley. This will take you to 6000 rpm with no problem and you will never notice a difference in the "below 1500 rpm advantage" the Performer says it has. I think 2-4's on a small motor steet car is a waste.

Fast63 · Mar 7, 2008

1000cfm total? WAY overkill.

woodsnake · Mar 7, 2008

1000 CFM at wide open throttle. The kit comes with a progressive linkage, so you run on the 'primary' 500 cfm 4V (the one in the rear), and then when you get after it, the second-ary (other 4V) comes online.

65ShelbyClone · Mar 7, 2008

Progressive linkage or not, 500CFM is about right for a mild 289/302.....1000cfm is far from it.

With that said, my vote is on a single quad intake with a 500-650CFM carb. Even 650 is overkill for the average 302.

D.Hearne · Mar 8, 2008

No matter the total cfm rating for the 2x4, it's not 1000 cfm. When you double the number of carb throats, the rated cfm's for a single carb is moot. They will only flow what the motor draws thru them. I don't know what your motor's build consists of, but if you decide to go dual fours, take the time to learn to tune the carbs. It will not be a "bolt on and go" sort of thing. If you don't tune the carbs to the motor, you'll never be happy with it. Two smaller carbs would be even better (like Holley 390's) but unfortunately Edelbrock chose to design their 2x4 intakes to where you cannot use Holleys and as far as I know their 500's are their smallest rated carbs. The only way to use two Holleys would be to use twin 2 bbls by way of 4 bbl to 2 bbl adapters.

Fast63 · Mar 8, 2008

edelbrocks and holleys have the same bolt pattern, except the edelbrock also bolts on to a smaller bolt pattern.... is that what the dual quad intake requires?

D.Hearne · Mar 8, 2008

They both bolt to the same pattern on the intake, but a Holley 4 bbl carb is longer than an Edelbrock/Carter 4 bbl carb. The Edelbrock carb pads are too close to each other to bolt two Holleys inline together. Offenhauser did the same thing with their 2x4 intakes.

Fast63 · Mar 8, 2008

lol, did they do that to put holley out of business, or was there just no room?

65ShelbyClone · Mar 8, 2008

They probably did it so you'd have to buy two Carter carbs(or preferably two Carter-based Edelbrocks) instead of Holleys. Some other intakes situate them sideways so either type of carb can be used.

D.Hearne · Mar 8, 2008

There's room, Ford sold an over the parts counter intake that mounted twin Holleys on a small block. Mustangs Unlimited sells a repop of this setup.(and the 3x2 repop as well) Granted, the rear carb is farther back on the intake with the Holley spacing, but it does work.

dodgestang · Mar 8, 2008

You don't need 8 barrels of carb on a street car.

D.Hearne · Mar 8, 2008

dodgestang said:
You don't need 8 barrels of carb on a street car.

2x4's aren't a "NEED", they're a "WANT" You get more WOW factor when you pop the hood and they other guys see multiple carbs. With a 3x2, I believe the overall performance is better than a single four, better throttle response, better fuel distribution, plus the WOW factor.

dodgestang · Mar 8, 2008

D.Hearne said:
2x4's aren't a "NEED", they're a "WANT" You get more WOW factor when you pop the hood and they other guys see multiple carbs. With a 3x2, I believe the overall performance is better than a single four, better throttle response, better fuel distribution, plus the WOW factor.

Preaching to the choir on 'want' vs 'need'

I always 'want' to go faster....and in my applications, the single works better for me and allows me to have a good mix of street and strip performance in the same package.

Changing the intake and using MSD is not enough to use a 2x4 setup IMO. You need to change the cam to support the different power band and then it is a domino to possibly the rear, the tranny, etc...

ratio411 · Mar 8, 2008

If you want the 'wow' factor, I would go with a repop 3x2 or 2x4.
Repop intake with the Holley carbs.

If you want to go back with a 4v intake, I would use a Holley carb no matter what!
They are so much better than the Federal Mogul (TRW) built Carters with an Edelbrock label.

The best quality I have seen on a new intake in a long time was my neighbor's Wieand Stealth he just got for his 302. Stellar quality.
The worst was pics of a Summit knock off of the E'brock RPM (Stage 3???). Looked like little kids cast it in playdoh.

Rusty67 · Mar 8, 2008

What about an RPM air gap with a 670 street avenger ?

D.Hearne · Mar 8, 2008

Rusty67 said:
What about an RPM air gap with a 670 street avenger ?

Good intake, but the carb size depends on what you're going to put it on. Just me, but I'm partial to Ford's A321 and all it's earlier forms for a single four.

65ShelbyClone · Mar 8, 2008

ratio411 said:
If you want the 'wow' factor, I would go with a repop 3x2 or 2x4.
Repop intake with the Holley carbs.

I agree to a point, but if you really, really want "wow factor," how about four downdraft Webers?

Or maybe eight stacks of Hilborn injection?

On a cammer.

D.Hearne · Mar 8, 2008

Even better, the EFI Weber conversion Best of both worlds.

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