Manifold / carburator Thermoquad vs Demon

[automate33]

Hello, I need some advices here



The 340 ci motor in my 71 Challenger R/T has been rebuilt during a restoration process a few years ago (before I bought the car), there is an Edelbrock Torker on top of it (single plane manifold) and Demon 600 cfm carburetor (i think). The rest of the motor is really similar to the 71 factory setup from what the previous owner told me.



The car produces 238 hp @ 6000 rpm to the rear wheels (recently measured on dyno), and has a great character, getting alive around 3000 rpm and screaming.

I think it kind of matches the factory specs : NHRA established that the high compression 340 motor was producing around 290 to 300 hp SAE gross.



As I am in a process of getting the car back to its factory specs, I recently bought a stock iron 71 340 ci manifold, and a totally redone 800 cfm Thermoquad spreadbore carb.

I would like to install those, but I wonder if putting the stock manifold, which is an iron dual plane, instead of the Torker (which is an aluminum single plane) is a good idea... I'm afraid of stepping backward doing this : more weight, maybe more low rpm torque but less top end...

And finally if I am keeping the Torker, the Thermoquad carb can't mount as is on the manifold because it is a spread bore carb with bigger secondaries. Or I will need an adapter/spacer... ?



What would you do there ?

  - Keep the Torker, measure the gap between motor and hood, buying a spacer, install Thermoquad on top of it

  - Install stock intake manifold, put the Thermoquad on top

  - Keep the Torker and Demon carb (don't really want to do this)



Anyone gone through this situation ?




Thank you for helping

attachement  :
Thermoquad for 340 RT Auto 1971 NOS Vs Demon Carburator (road demon) 625 cfm i think

[Chryco Psycho]

The Factory intake was actually one of the best intakes available for the 340  it works very well , it was available in an alum version through Mopar performance for years so you may be able to find one of those  , paint it & it will look original !
The Demons were hit & miss they are a good design & should work well but had numerous problems , maybe 1 in 3 worked properly , the Thermoquad is similar when they work right they are a a great carb , the bakeklite body would often warp causing leaks though , I think you will be happy with the performance of the factory intake & it is worth trying the TQ .

[Cuda Cody]

@automate33   I would vote for #2 unless you can find the Mopar Performance aluminum version.  I really like the Thermoquad.  That 71 is a super rare one year only carb too.  Worth some 

[RUNCHARGER]

I totally agree, the stock TQ manifold is one of the best available and is better than a lot of aftermarket designs, you can't go wrong with it. A good running TQ is a joy to drive but not everyone can get them to run right.

[blown motor]

I have a 340 with the stock intake and a 650 Eddy. I have great low end power but if you kick it down from 70mph it's not real exciting. I think you'll like the stock intake and the extra cfm carb on the street.

[automate33]

Thanks!!!!

i will try this year on dyno:

Thermoquad on Torker

Thermoquad on stock manifold

Who think that stock manifold is better than Edel Torker?

[Cuda Cody]

I prefer the stock intake on the 340's.  Just me though.     Both are very good and with a nicely tuned carb will preform well.

Switching intakes while on the dyno kinda sucks, but if you have the time it would be cool to see the difference in the numbers.

[RUNCHARGER]

I think the stocker will edge out the torker.

[Chryco Psycho]

  to a point , I think the stock intake will perform better for most of the power band but my lose a little in the upper rpm

[HP_Cuda]

Would be interesting to see on a small block.

I agree with Neil, you will see a bump at the top end.