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Fuel Efficient Carb

70chall440

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I know that some people are emotional about carbs and I agree that they have and do work but I do not ever intend to run another one on any car if I can help it. Properly set up EFI with a good electrical system is hard to beat. I will say that adjusting timing and fuel with a laptop is an interesting experience.
 

i_taz

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I just put a Thermoquad on a 440 and am happy with it. Haven't checked mileage yet but like all spreadbore design's fuel economy was the objective. Wouldn't a 360 come with a spreadbore intake ?
 

shebacat

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1974 Challenger, 360, 518OD, 3:23 stock thermoquad .I just did three road test and I'm getting 21.6 mpg highway that's imperial gallons 2100 rpm at 60mph.
 

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fasjac

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EFI will be the most efficient & the cost is comparable to a carb now .
Eddys are the Least tunable carbs , I like using the Proform carbs great value & performance , I have been ableto get over 20 MPG on 440s & 18 MPG with a 512 strokers , Overdrive will help also to keep the revs down at high speeds .
I also get around 15-16 per gallon
on the highway in 5th with 500 stroker six pack. That’s only cruising at 65-70, 2300rpm though. Mat it and it’s single digits.
 

budascuda

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I also get around 15-16 per gallon
on the highway in 5th with 500 stroker six pack. That’s only cruising at 65-70, 2300rpm though. Mat it and it’s single digits.
Yeah, single digit fuel economy, but double digit fun........😀
 

money pit

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I know that some people are emotional about carbs and I agree that they have and do work but I do not ever intend to run another one on any car if I can help it. Properly set up EFI with a good electrical system is hard to beat. I will say that adjusting timing and fuel with a laptop is an interesting experience.
What EFI are you using. I hear good and bad about FiTech and Holley. Thanks
 

70chall440

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At the time I wrote that I had a Fitech system on a 52 Dodge with a 56 Desoto Hemi in it, but I still have 2 EFI 6 pack systems, one running a FAST EZ system and the other is using a Holley HP system plus I have a Holley Terminator Max Hemi system for my 5.7 that will be going into my 71 Charger.
 

money pit

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At the time I wrote that I had a Fitech system on a 52 Dodge with a 56 Desoto Hemi in it, but I still have 2 EFI 6 pack systems, one running a FAST EZ system and the other is using a Holley HP system plus I have a Holley Terminator Max Hemi system for my 5.7 that will be going into my 71 Charger.
Thanks.
 

money pit

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I just put a Thermoquad on a 440 and am happy with it. Haven't checked mileage yet but like all spreadbore design's fuel economy was the objective. Wouldn't a 360 come with a spreadbore intake ?
When I bought the engine it didn't have an intake manifold. The sell gave me a Performer intake manifold. Will this work with a Thermoquad?
 

Cuda416

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When I bought the engine it didn't have an intake manifold. The sell gave me a Performer intake manifold. Will this work with a Thermoquad?

it it's a spread bore (secondary larger than the primaries). You can also get spacers/adapters that go from spread to square.
 

money pit

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With the right cam , porting , intake & heads gearing I have been able to
What kind of a cam are you talking about? A stock cam? When I had the engine rebulit the builder said he was going to put an RV cam for more torque. Could this be a reason for poor MPG?
 

terrywalker

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My 71 Challenger convertible is a completely stock 340 with the original Thermoquad carb and has the original 4 speed and 3.23 sure-grip rear. On the highway at 60mph, I have consistently gotten 21-22mpg if I keep my foot out of it. Just nice easy cruising. City driving, about 13-14 mpg easy driving.
Terry W.
 
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