Technical Spreadbore to squarebore adapter

I am getting parts ready for a new build, this will be a budget build to start ,so I want to use as much of the stuff I already have. I have an older Quadrajet that is in good shape but will be using a square bore manifold. Has anyone had success with these adapters. I know they work but how well is the question ,if I need to purchase a square bore carb so be it.
Thanks
Dan

 

I ran one with a spread bore Holley carb, car ran great, infact it was with that combo it had the best seat of the pants acceleration

 

Is the square-bore pattern the same as a Holley? I recall the day when even the lowest of parts store had a wall of adapters to paw through.

 

Qjet on a square bore adapter will kill a bunch of performance and make tuning a pain.
Does it work. Yes. But not to its potential.
You didnt mention which engine you have but in a budget build you really cant go wrong with a factory spread bore intake.
IMHO I would go that route instead of getting a square bore carb. Only because I like the Quadrajet better.

 

I’ve been running a quadrajet on a square bore L79 intake for more than 30 years. Runs fine. Mind you it’s a street car mild 327 not looking for all out performance.

 

Make sure the adaptor has enough room to seal with a gasket. I had a cheap adaptor that developed a vacuum leak. The adaptor had an area that didn’t fit the intake.
Bought the one with the 4 holes and problem solved.

 

Thanks guy’s .Guess I should’ve mentioned engine etc. I bought a 66 Dodge Dart from a fellow HAMBer which isHAMB friendly since it carries over from 63. 360 Magnums are plentiful and affordable in good running condition. Basically an LAEngine so ok HAMB wise, just need a carburetor intake and a points style distributor . All the intakes I find are square bore, I have a good qjet so would like to use for now anyway.
The plan for now is to get the car running and drivable ,then upgrade as funds and time allows. Not sure what direction I will ultimately go Gasser, SS look or sedate street car? Drop it in the weeds ?Time and $$s will tell.
Thanks for the input, I’ll be back for more schooling.
Dan

 

In the early 80's Mopar put q-jets on some vehicles when they could no longer get Carter's , so there's factory q-jet/ Mopar manifolds out there .

 

Yep, I'd search locally for a spreadbore SBM intake. They are not that hard, especially if you aren't allergic to cheap aftermarket deals. I won't post manifold names, but you should be able to find a few to look for.
I will suggest getting a gasket that seals well, and covers all open areas on the carb base and intake. Mix 'n match can lead to some strange stuff.

 

2OLD2FAST do the old LA manifolds bolt up to the Magnum heads I’m new to Chrysler stuff so I’m learning. I believe the thermal quads have the same footprint of the Quadrajet not sure though I’ll look into factory spread bore manifolds this would be an inexpensive option.
Thank you
Dan

 

Magnums the holes are the same location, BUT at a different angle. They must be drilled with a fixture or use a mill.
PM sent.

 

The Magnum engines use vertical manifold bolts versus the angle bolts on the LA engines. So there is no spreadbore manifold for the Magnum engine. So-you will have to use an adapter. I've used them with no ill effects. My 68 340 Dart had an Edelbrock Torker-the original one with an adapter with a 850 Thermoquad. The car flat out screamed.. Is your Dart an automatic car? If so, you have to deal with a functioning kickdown linkage, unless you use a manual valve body in the trans. The early A bodies used kind of a wonky kickdown setup. It has to be on there, or your transmission will have a short life!

 

Most likely the car will be a AT unless I find a good deal on a 4speed, the car is an AT car,with an AT I’m aware of the lockdown linkage , may go manual valve body again my budget will determine where I go. Looking at headers the Hooker fender well exit headers won’t allow for a column shifter. Looks like things will be fairly tight.
Dan

 

I don’t know why people are suggesting getting a different manifold, use what ya got, get the adapter and be done with it, spend your $ on something that matters more.

 

Let me look in my junk

 

Your doing a budget build. Buy the adapter plate. Bolt it on and go.Ive used them for years. As time goes on the parts will change to what you want.

 

Sorry , only way I know dodge used a q-jet is the neighbor bought a dump truck , I didn't know Dodge ever used a q-jet & looked it up to verify it wasn't a previous owner adapted cobble job

 

I’d pick up a square bore Holley four barrel and use that. A nice 650 will run you about $50 and a few extra dollars to do a nice rebuild on it. I sold three of them at swaps in the past year and it was pulling teeth to get $50 a pop for them.

Might be easier to get your kick down linkage to work with the Holley set up and why give up hood clearance on a carb adapter that might better be used for a taller performance intake down the road when the budget permits.

 

..

Just put the adapter on and run it, call it good and enjoy it....

...

 

The use of a spread-bore to square-bore adapter using a spread-bore carb to a square-bore intake is not GENERALLY a good idea.

Sometimes the stars align and it works (as a number of posters have mentioned in this thread) but never near the potential of the engine (as mentioned by at least one poster).

IF you have both the carburetor AND the adapter, and just wish to get the engine running, try it.

If you do not have the adapter, I would suggest the price of the adapter would be better used if applied to the cost of a square-bore carb that fits your intake.

If you do decide to use the adapter (your car, your choice), I would STRONGLY suggest extra caution with gasketing prior to installation. Often, the gaskets supplied with the adapter will not seal. Check the sealing with the adapter to the intake, and also the adapter to the carburetor. Often, one must purchase a mounting gasket for the original carburetor to intake, AND a mounting gasket for the carburetor being used. More money that may be applied to a square-bore carb.

Let us know what you do, and how it works.

Jon.

 

Thanks all for the input, I’m doing a budget build but don’t plan on being cheap to the point of penny wise and pound foolish. If I can pick up a Holley 650 for 50 to 100 $s I’ll go that way for sure. I’ll keep ya all posted on my progress.
Dan

 

If you go with the manual valve body in the automatic, be aware that they are over 400.00 now and then you would probably want an aftermarket shifter. Stay away from those HORRIBLE fenderwell headers!!! TTI makes underchassis headers for these early A Bodies. They aren't cheap, but I don't think the Hooker fenderwells are cheap either. TTI is the Cadillac of Mopar exhaust systems.

 

Thanks for the info. The Hookers are expensive also but they were all I came up with in my limited searches. I’ll check out the TTI or possibly build my own probably won’t go with a manual valve body to start.
Dan

 

Dodge trucks used the Q-jet in '85-'86 on the 360 motors, I had a NOS one for a while.

 

Carter was making "new" Quadra Jets years back and they were excellent. Rebuilts were more miss than hit. I would get 3 before I got a good one.

 

I've run those adapters both ways to make carbs and intakes match. Never an issue either way.