TQ replacement

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crewchief

A & P Mechanic
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Looking to swap out my TQ for another type of carb. Anyone out there have any direct replacement ideas, Holley vs Edelbrock? Plug and play, not looking to modify linkages.

The engine is a '70 340 with stock spread bore manifold, bored 40 over with Keith Black KB243-040 Hypereutectic Flat Top Pistons and a Comp Cam CL20-210-2. Not for racing, too old now just for cruising around.

Thanks for your input, Jack
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Holley and Eddy will both work. The one that will hook up the closest to the TQ would be the eddy, using the eddy adapting plate that can be bought at O'reillys.
 
They told me it wasn't compatible with stock spread bore manifold.
 
Holley 4175 is a direct replacement for a thermoquad.
 
Holley used to make a direct replacement for the TQ. One was a vacuum secondary and the other was a double pumper. I had the double pumper. It may be the part numbers posted above, I just don't remember.

You do have one other option, besides the Holley replacement or using a adapter, which I hate.

You can find someone who is good with the Rochester Quadrajet and use that. It's a bolt on. I know where a good used one is. Probably real cheap. But I don't think they are making those new either.
 
Thanks for the input, I'll have to do more research before pulling the plug

The little Demon three barrels are fine carburetors. I have one on my 75 F250 and love it. They will require the thin (about 1/16") plate to run on a spread bore intake. It's not the 1" thick aluminum crap. There's no need for that. It's like 12 bucks. ANd I'm not sure I would go with the 750. What size is your Thermoquad now? They are either 800 or 850 but Carter measured flow differently, so when you go to another style carburetor, to get it right, you usually need to go down a size or two.
 
My attempt here is to show that the thin Edelbrock plate covers the entry in it’s entirety making a good seal. So any squarebore carb you decide on will fit fine.

Linkages will almost always need adjusting and maybe modified to fit.
The Edelbrock adapter posted above works excellent by the way but you still may have to tweak the OE rods. Keyword, “MAY!”
That’s what happens when non stock parts are used and not specifically designed for what you have. I myself use Lokar cables. There easy to do. Work great.

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The little Demon three barrels are fine carburetors. I have one on my 75 F250 and love it. They will require the thin (about 1/16") plate to run on a spread bore intake. It's not the 1" thick aluminum crap. There's no need for that. It's like 12 bucks. ANd I'm not sure I would go with the 750. What size is your Thermoquad now? They are either 800 or 850 but Carter measured flow differently, so when you go to another style carburetor, to get it right, you usually need to go down a size or two.
Thanks, my TQ is 800 cfm. I was thinking to go with a 750 max.
 
Thanks to everyone, just purchased the Demon 1901 from Jegs along with the universal carb install kit.

1 3/8" primaries were suggested since it will never see the strip, no adapter needed.
 
Thanks to everyone, just purchased the Demon 1901 from Jegs along with the universal carb install kit.

1 3/8" primaries were suggested since it will never see the strip, no adapter needed.
I have a street demon 750 and I really like it. You will like your demon they’re great carbs IMO.
 
Thanks to everyone, just purchased the Demon 1901 from Jegs along with the universal carb install kit.

1 3/8" primaries were suggested since it will never see the strip, no adapter needed.

That's true. You don't need an adapter, but you are going to have to have the plate I described or it will not seal around the secondary bulges in the intake manifold.
 
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