Thermo-Quad Carb Tuning

by **dave-r** » 22 Apr 2006 13:58

This might come in handy for those that have one of these fitted.

by **dave-r** » 22 Apr 2006 14:01

More.

by **ianandjess** » 22 Apr 2006 15:15

thanks dave
ive got 1 sitting on the shelf in my shed just waiting to be installed so im sure that info will be very handy

cheers ian

by **dave-r** » 22 Apr 2006 15:27

They are actually a very very good carb. I don't know why they get such negative comments. Probably because they were installed on cars when performance figures were generally falling. People used to say the same things about the "smog motor" 400 inch engine. Fools.

These carbs have great throttle response, give good mileage for the light footed, yet have plenty of flow in the secondaries for when you "need" it.

by **David** » 23 Apr 2006 1:32

I have had trouble with the floats in mine. They seem to have a little disagreement with the 93 octane fuel i need to use now since I have had my engine rebuilt.

by **ianandjess** » 23 Apr 2006 9:39

yep i had 1 on a 302 clevland years ago & was quite impressed with it thats why i chose 1 for the 318
cheers ian

by **transman** » 26 Apr 2006 23:57

One of the complaints about this carb is the plastic body.
They are known to warp, and whatever you do go easy anytime you've got a screwdriver near one.
Are they a good carb? I've used them in the past, and was happy with them. Do they work as well as other performance carbs?
I guess the fact that they only saw a short life at the OEM level, and they never appeared in the performance market other than on Mopars (for the most part anyway) may say it all.
I've got a friend who has a really neat 340 1971 Duster, and he yanked the thermoquad off and put a Holley on it. He claims with the Holley, his Duster is a much better performer.
transman

by **dave-r** » 27 Apr 2006 7:39

There is a lack of tuning parts for them that is very true. So they are not always the best choice for a performance engine. But many parts from the other Carter/Edelbrock carbs do fit. There were some very big versions of this carb that flowed very well. They fitted them to quite a few performance cars of the 70s but as stock they were tuned for 70s low power and low emissions standards.

The plastic body is only damaged by heavy handed owners. They do not warp of their own accord. It insulates the fuel from engine heat and delivers a denser charge into the engine. This also helped control detonation with low octane fuels.

And everyone who cannot tune a carb right to save their lives will tell you a "I swapped this carb for that one and it worked much better" story.

What they never say is "I and the other last few owners have messed with this carb so much we need to start again with a new one".

A carb only delivers air and fuel. If it is correcly matched for the engine it is on, working and tuned correctly then it will perform almost as well as any other carb that flows the same.

There will always be slight differences though. Like the denser charge mentioned above. Or the relative size of the primaries to the secondaries. In this case the smaller primaries give better low rpm/light throttle pressure mileage and sharper off - idle throttle response. But with some loss of the sudden WOT response. Not as bad as a vac secondary Holley though.

by **patrick** » 14 Jan 2009 6:13

I still have mine. :biggrin:

It was taken out, twelve or, so year's ago. Still in mint shape, though. Stored, in the house. No cracked, plastic bowl's, or weathering. Parts and, putting that thing back, to original, are different subject's, I think. I talked with Eddie, about those Thermoquad's, last week. The bennefit's, are huge! Thermoquad 850, as opposed to a Holley 670, on the 340. Wow! Would like to rebuild the Themoquad but, love the Holley Street Avenger. Great pickup speed, too. Espesially, at high speed. Anyone want to tell me why, I should change back. Eddie, your "AWESOME"., Just want to here, what the other boy's, have to say.

by **dave-r** » 14 Jan 2009 9:16

I doubt it would work any better. I would leave well alone. :wink:

by **patrick** » 15 Jan 2009 5:30

Thank's Dave. It's pretty neat, to have all the original goodie's that came with the car. If I never use them again, I'll still keep. They're still great conversation piece's.

Therom Quad