Mopar intake manifold

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3

36DodgeD2

36DodgeD2
Joined
Dec 15, 2013
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Milford,Pa
I have an intake manifold casting #4100340-3. I believe it to be a 1978 360 truck manifold with a quadra jet plenum. It had an aluminum adapter with a Holley 750 df/dp. I bought it this way and am in the process of doing the seats and guides on the heads. When I took off the carb I was surprised to see that style plenum. I searched for pictures of this style but did not find anything. Is this what I think it is or is it something else??
 
very little if anything at all. when carter carb went out of business, mother mopar picked the q-jet as a replacement. would not have made too much sense for them to change manifold design to just change brand of carb. if any change, it would have been very very minor and a running change also.
 
Square Bore Carter (Edelbrock)
vs
Spread Bore for the Quadrajets

Square bore on the right:

383 stock intake:
1017161057.jpg


70s small block 4 bbl intake, spread bore:
Screenshot_20210323-091202_Chrome.jpg
 
Spread bore Thermoquad or Quadrajet

EDL-2176_GN_ml.jpg
 
Well, in my hast with my manifold I didn't notice that the gasket for a QJ was still on the manifold and it turns out it was over a spread bore plenum like the one in the bottom picture of the two blue manifolds. So, I guess I have a 79 360 manifold for a QJ or thermo quad. Thanks to all that replied.
 
All SB 4bbl factory manifolds (so far as I know) were spread-bore starting with 71

In 72 they had EGR without a valve. This consisted of "floor jets" in the bottom of the plenum which connected with the exhaust heat crossover

73/ later they had external EGR valves. Never heard of a QJ specific manifold, AKA either TQ or QJ. I about **** the first time I saw a FACTORY Mopar QJ "back in the day."

They are considered to be very decent manifolds
 
I'm running an LD340 with a thermoquad on it that has been bored out to run it. Was just wondering if there was a difference to run a quadrant. But looooove my thermoquad.
 
either carb, set up correctly, will be a very good unit. problem is there are people that can overhaul/rebuild them but very few know how to make them work. in s/s racing, set up properly they are better than a holley. i will run 1 on my carbed magnum on the cast iron intake and attempt to wring out a lot of mpg. there are 3 diff cfm. 750, 800, and the hard to find 840.
 
spl440 said:
I'm running an LD340 with a thermoquad on it that has been bored out to run it. Was just wondering if there was a difference to run a quadrant. But looooove my thermoquad.
Click to expand...
Yes! You run slower & make less power with a QJ.
 
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