Holley Spread Bore Quadrajet?

[LT512]

I posted this on another board, but didn't get a lot of responses. I am thinking it would be best to go spread bore to spread bore on my carb and intake (performer 2176). Would the Holley 0-08555C be a good one? It's a little pricey but has no call for an adapter plate and is reasonable size at 650cfm. I'm wanting to have things mate up without adapters and such. Mechanic is wanting to stick to Holley. I was looking for some mopar guys that might have done this before. I found one good post on A Body forum from 9 years ago. Is this a good setup? Engine is stock and yes, I'd like to get a 8.25 AHB axle/gears eventually, but they are hard to come by within a reasonable drive.

 

[Oldiron440]

I haven’t had my hands on a Holley spread bore carb in forty years, maybe longer. I can’t even remember what it was on. On a Performer intake I believe you can use a plate under the standard carb, no spacer needed. The plate is just like a gasket made of 12 gage steel, you put a spread bore gasket on the intake then the plate then a Holley gasket and a standard Holley carb.

I did this on my Dodge half ton with a 360 and a 360, the plate came with the new intake manifold.

 

[LT512]

I haven’t had my hands on a Holley spread bore carb in forty years, maybe longer. I can’t even remember what it was on.

Probably the same carb. They still make them.

 

[Oldiron440]

Same carb but it’s an odd duck.

 

[Oldiron440]

Do you have a 318 or 360?

 

[Camtron]

Have ran it on a spread bore intake am running it on a square bore now, it’s made for both. Basically thermoquad, user friendly, easy to tune, starts up first crank and runs great when it’s -32 and below.

 

[LT512]

Do you have a 318 or 360?

318 and will be using the Performer 2176 intake

 

[LT512]

Have ran it on a spread bore intake am running it on a square bore now, it’s made for both. Basically thermoquad, user friendly, easy to tune, starts up first crank and runs great when it’s -32 and below.

Have ran it on a spread bore intake am running it on a square bore now, it’s made for both. Basically thermoquad, user friendly, easy to tune, starts up first crank and runs great when it’s -32 and below.

View attachment 52733

Thanks! I asked about that one but the Holley tech support guy wasn't as thrilled with that one. I know you had told me before you had ran that one, so I asked about it.

 

[Camtron]

Cool. Yea, I’ve ran it on the same set up you’re looking at with the 318 and performer intake. Works great. A 13 year old with a screw driver should be able to figure out how to tune them. Have ran it daily for the last 5 years without issue from a 318 to a 5.9mag. Happy hunting.

 

[LT512]

Cool. Yea, I’ve ran it on the same set up you’re looking at with the 318 and performer intake. Works great. A 13 year old with a screw driver should be able to figure out how to tune them. Have ran it daily for the last 5 years without issue from a 318 to a 5.9mag. Happy hunting.

I really do appreciate you giving your experience sir. It helps. I got a mechanic that is going to do the work and he is pretty set on a Holley of some sort. If they called it a Holley demon that would probably be better! lol. It's a brand they bought out, I guess.

 

[Oldiron440]

I love my Holleys but I think an AFB or the street demon is the way to go.
I used a 600 vs Holley on my 360 and it worked very well but I would stay away from the spread bore Holley.

 

[Camtron]

I really do appreciate you giving your experience sir. It helps. I got a mechanic that is going to do the work and he is pretty set on a Holley of some sort. If they called it a Holley demon that would probably be better! lol. It's a brand they bought out, I guess.

Then tell him to order your carb. He’s the mechanic putting it together right? I don’t understand the dilemma. I may actually be one of the few people on here to daily drives their car and has it set up for turn key operation day to day and extreme weather changes in the Midwest.
Just want to help if I can.

 

[LT512]

I love my Holleys but I think an AFB or the street demon is the way to go.
I used a 600 vs Holley on my 360 and it worked very well but I would stay away from the spread bore Holley.

Thanks. I guess I was just looking at why one is better than the other is all. Appreciate it.

 

[XfbodyX]

Holley spread bores are just as good and functional as any spread bore imo. You might consider the mopar version as it would accept much of what is already setup on your car.

 

[XfbodyX]

Even more to think about, on a semi stock teener save a bunch of cash and run a factory spread bore manifold. Or not.

On the holley spread bore the primaries are even smaller then your current carter bbd or holley 2280 2 barrel and in a not so perfect world better mpg could happen.

 

[Oldiron440]

The reason I don’t care for it is reminds me of an OEM Holley, the goofy fuel bowls and float setup along with parts availability, you can generally fix and reseal any Holley from parts available at O’Reilly auto parts but not that one.
I would go with a standard square carb but good luck.

 

[XfbodyX]

You can still easily get all the parts for this type carb from fuel bowls to floats to current rebuilds kits. Via AED, Holley, USA Carb, multiple ebay sellers.

There are even still NOS units to be bought at decent prices.

Simple $50 kit and even a nos unit. Made for a low comp 340 so maybe jet down the one below is.

 

[PursuitSpecial]

If you can find one, a Holley model 4011 is an excellent spreadbore carburetor for just about any Mopar V8, I ran one on my 318 and it had extremely good cold manners, response, power, and highway fuel economy compared to the original crappy thermoquad. I'm running the same carb on a 400 HP now and it is very satisfactory, though it's a bit small actually and I had to take the check ball out of the vacuum motor so the secondaries open sooner to break my tires loose for some fun, the 318 on the other hand could barely handle them rolling open slowly. It's a very tuneable and simple carburetor, plus the mopar linkage stud adapter bolts right on.

 

[AHBguru]

Run the correct Quadrajet or TQ, and be done with it. Anything Holley or Edlecrock is aftermarket, and as I posted elsewhere, they're very expensive with iffy quality. The only exception I'd consider might be the Street Demon TQ, which isn't a true spreadbore, but it sounds like quality there is still the typical Holley hit-n-miss.

A good Qjet or TQ will easily outperform a lousy AFB/AVS, and will get better fuel economy.

Look for a 9300 series TQ, and for the Qjet, Look for a 17085411 or a 17085408. Those are bolt-on Mopar carbs.

 

[AMC Diplomat]

Even more to think about, on a semi stock teener save a bunch of cash and run a factory spread bore manifold. Or not.

On the holley spread bore the primaries are even smaller then your current carter bbd or holley 2280 2 barrel and in a not so perfect world better mpg could happen.

That's the real answer. Factory spread bores can be had for cheap compared to aftermarket Chinese made manifolds