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Good info on here for those shopping for a new carb. Gotta love these forums!
I give up
- Thread starter 70NPORT
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BillGrissom
Active Member
Rochester made a Quadrajet as a Thermoquad replacement in the early 1980's. I have a Quadrajet I will try on my 383 someday, plus a Thermoquad, and Holley Economaster. Currently, I have a Holley Pro-jection 670 cfm TBI (since 1996). It is a bit quirky, but better than the original Rochester 2 bbl. My final solution will probably be a Holley Commander 950 TBI. Before trying above, I want to install a Offy Dual Port intake for better mileage and driveability, but my A-bodies are keeping me occupied.
I doubt Edelbrock's are inherently bad, and thousands use them on Mopar BB's. Search the FABO site for many posts. I suspect there is a blockage in the idle circuit which is making it run bad, either in the idle bleed (screw adjustment) or the the air bleeds at the top (I think yours has them). It could also be that the bowl is overflowing at idle, due to an old float needle or grit keeping it from closing. My Dart has a Carter BBD, which I think is similar, and I had trouble first running it. It would start up and run fine, then want to die after ~30 sec. I found the float tang was bent so the bowl was over-flowing, making it rich. Sounds like your symptoms.
70NPORT
Old Man with a Hat
Hey all, thanks for the responses to this prolonged problem I'm having. has2bmopar; yeah just tried shooting compressed air into the needle seats (both left and right side) a few days ago (been busy as it is) l-- it did not make a much of a difference....idle will still get choppy after a couple minutes, although not quite as bad, but still choppy. I've been smelling gas when the car is shut down; and today I was under the hood for something else, I turned the car off and I noticed raw gas "boiling" in the second fuel filter, just before the carb (I've got two Fram "clear" filters). Edlebrock says the carb could be getting more fuel pressure than it needs (5-6psi is norm)...and gas could be coming up out of it after turning the car off..BUT I still have the same 2bbl stock mechanical fuel pump down there so I don't think the problem is there. This damn thing is really getting on my nerves now. I still have to check the floats, but I imagine those are setup at the factory by Edlebrock, being so I don't see how the float position(s) could change much after just bolting it on and running it...but I could be wrong.
has2bmopar
Senior Member
It appears they make a Viton needle and seat set for $10-$12 at Summit, but I'll do some additional checking to be sure as to what you have now, before you make a decision on this, at this point.
If you have not already, check to see if your choke opens completely with the ignition switch on, in a reasonable amount of time. If not, be sure your ground wire is on properly, assuming that your power source is good.
You can loosen slightly, the top screws on top of the carb, so you can rotate your manhole covers enough to see the top of the metering rod/piston assembly, but not so much as they are not held in position by the covers. Then turn your screws down just enough to prevent movement, without distorting the covers.
Then start the engine to check if your metering rods are being drawn and held down by vacuum at idle.
If not, look for a vacuum leak... PCV, brake booster, etc.
If you have not already, check to see if your choke opens completely with the ignition switch on, in a reasonable amount of time. If not, be sure your ground wire is on properly, assuming that your power source is good.
You can loosen slightly, the top screws on top of the carb, so you can rotate your manhole covers enough to see the top of the metering rod/piston assembly, but not so much as they are not held in position by the covers. Then turn your screws down just enough to prevent movement, without distorting the covers.
Then start the engine to check if your metering rods are being drawn and held down by vacuum at idle.
If not, look for a vacuum leak... PCV, brake booster, etc.
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1966newport
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more like you found a lazy engine guy
70NPORT
Old Man with a Hat
Damn those things are REALLY expensive.
commando1
Old Man with a Hat
After years and years and years of always of always trying to make things better by swapping Holleys, Eddys, modified carters, etc, on and off like diaper on a baby, I recently tried something different. I sent my T-Quad smogger out to a guy who restores them to 100% factory spec and flow tests them before sending it back.
I popped it on and after doing some simple primary jet enrichment adjustments to compensate for my removing mot of the smog crap, it runs like it just came out of the dealership.
A lot of times one can't be smarter than the factory engineers.
I popped it on and after doing some simple primary jet enrichment adjustments to compensate for my removing mot of the smog crap, it runs like it just came out of the dealership.
A lot of times one can't be smarter than the factory engineers.
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70NPORT
Old Man with a Hat
I have 2 T-quads in my possession right now in my parts cabinet. Big ol' ugly things but they are in good enough shape to be rebuilt...don't know the cfm ratings on them tho. I always heard to stay away from those due to the "phenolic resin" main body....it warps in shape over time b/c of the heat(?) Old wives tale, then? I dunno sounds like its no problem for you.
I had a T-quad on a 73 Challenger with a 340. That phelonic center section warped and leaked gas and was replaced under warranty twice. I could smell gas in the car it leaked that bad. Ended up putting an eddie manifold and holley carb on her. No more leaks.
70NPORT
Old Man with a Hat
Guess it is NOT an old wives tale then.
commando1
Old Man with a Hat
Many did. Most of them didn't.
When someone can't get their engine to run smooth, they first thing they hear from the know-it-alls is: "it's those damn plastic thermoquads. They all...."
Personally, I find them overwhelmingly complex but there also was a time I found a tieing my shoelaces overly complex...
For less that the price of a new aftermarket carb, I got an as-new carb designed for my engine and it was practically plug 'n play out of the box. Every other person swears by Scott Smith's T-Q's.
By the way Demon Sizzler is now out of business for those that knew who he was.
If I was building a hi-po engine, then I'd definitely go aftermarket. I'm out of the RoadRunner chasing game now.
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BillGrissom
Active Member
Ditto commando1. Many people on forabodiesonly adore the Thermoquad. The problem is getting a good one and parts are getting rare. That is the carburetor I would use, if I wasn't using EFI. Nothing else has such tiny primary bores and monster secondaries. I do have a TQ to play with, just because I think carbs are neat and I used to design aircraft fuel controls at Bendix.
The Quadrajet is the closest equivalent. It also has people that swear by it and others that swear at it. When new, it was probably the most efficient 4-barrel carb made that still had power. Mostly used on GM cars, but factory on some Mopar's in the early 80's.
The Quadrajet is the closest equivalent. It also has people that swear by it and others that swear at it. When new, it was probably the most efficient 4-barrel carb made that still had power. Mostly used on GM cars, but factory on some Mopar's in the early 80's.
70NPORT
Old Man with a Hat
Commando1. said:
commando1
Old Man with a Hat
Never.
Plenty of 400's though, so almost the same thing.
1966newport
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its lean at idle, as choke goes off it gets more lean
I installed the 1406 Eddie (600 cfm/electric choke) on my 400 and it runs like a top. Took an Ocean City cruise for a total of 311 miles and got 15.5 mpg.
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