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thermoquad

motorhead55

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Anybody use a rebuilt thermo quad from summit racing? Or should I go to a spread bore Holley?
This is for a mild 440 10-1 compression and mild cam to be used for normal street driving.
 
I would go for the TQ over that spread bore Holley any day and I'm a Holley guy! I have never liked the spread bore Holley. On the other hand, I have had great results with TQ's. Try and dig up the secondary air door tool for adjusting. It makes that job much more pleasurable!
 
Seems that these carbs are geared more towards the 400 B and the 440 RB motors @ 800cfm. The 383 is a B motor and is a 6.3 liter engine where the 400 B is a 6.6 liter. How well does this carb work with the 383 B? I am trying to get a good reliable carb for my 383 66 Ply Satellite @ .030 over and a mild street cam. Mostly top rpm is 5800-5900 rpm. I started out with a 3310S Holley 750 cfm and decided against it. Plumbing nightmare. Went with an EBrock 1407 750 cfm. Vacuum Secondaries. Have the metering/jet kit and I still cannot get it dialed in. Bogs and bucks but once up to speed it runs acceptable. Idles really rough unless I feather the accelerator or put it in neutral. Once in gear cough and sputter and then it catches. Off Idle stumble I think is what it is doing. Just want a smooth, easy to adjust, bolt and go carb. So far the car is not dialed in to where I would like it...cr8crshr/Tuck
 
The summit racing TQ's are newer ones, and some don't have bowl vent valves or bowl vents at all. I ordered one and ended up getting a marine version. I sent it back and found some parts to just build one for my car. If you don't really care about originality, then go for it. The price is not too bad, or you can go with an Edlebrock AVS thunder series.
 
Most TQ's are geared for emissions so they will be a little lean. But certainly try it. Carter made a strip kit for them but pretty sure it's obsolete now. Even though a properly tuned TQ will work better than a Holley, you might have a hard time calibrating it. In that case I'd go with a Eddy AFB where calibration parts are easily obtainable. And I'll even suggest trying a Q Jet off a big block GM like an Olds or Cad. Chrysler even used the Q Jet in the 80's on 360 trucks.
 
Use a 650 or 800 cfm EDE AVSThunder.... not the 1407 (750 cfm ) AFB Performer. The AVS Series works great !
I Also always use the PINK Springs...the trottle reponse on engines with high vacuum is much better

Also never had luck with those "rebuit " carbs ... the only way to buy a "rebuilt carb" is either from Cliff Ruggles ( Q-Jet )..he built one for me...3 years ago --- a MASTERPIECE of Carb ! or for the TQ issues Demon Sizzler ( but I am not sure if he is still in buissiness...)
Hope that helps
 
The large primaries TQ (@1.50 inches) is rated at 850 CFM's and was also used on 340 & 360 engines. But not exclusively. The smaller primary carb (@1.38,IIRC) is rated at 800 CFM's and was used on the 318-340-360 & 400.

If were I doing this project, it would certainly be the big primary version.
Stip kits appear on line once in a while. MAKE SURE, you do not get the kit for the first year TQ. That is a different metering system. Use the oldest one you can find except the first year model. 71 and on. Truck carbs have less emissions. Even later years.

To help tune your TQ on the cheap, use AFB rods and clip them 3/4 of an inch shorter from the top and rebend 90*'s. The old AVS rods are 3 step and the modern AFB's are 2 step. The TQ is a 3 step. Your just stuck with the jet sizes that are in there now unless you find a cheap core.

The secondary side will likely like a enriching. They can be drilled out.

Not having much money when I was younger, (not that there's a big improvement now with 2 in collage, LOL!) I opted for the cheapest and used material I could scrape up for. A $20 TQ core and a $25 rebuild kit were it for me. I learned these carbs. There a little bitchy if there not adjusted correctly before bolting it on. But it's simple math. Little money spent on a big CFM carb. Bolts right to the OE or M1 single and away I go. Just take your time with it.

If the TQ isn't used, the other Carter design I'd recommend is the AVS & not the AFB since the secondary air door is tuneable like the TQ. You can wack the go pedal hard without a bog instead of roll into it to avoid the bog on AFB's. Edelbrock's Thunder series is a modified AFB with a AVS air door.

650 stock, mild and a fairly built up small block or stock big block with hwy gears.
800 for big rpm small blocks, low decks and raised decks from mild to fairly well built street terrors.
 
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