moparcustom

ok so i got a 100 custom with a 318, with the dinky little 1 barrel carter on it that is a peace and not worth rebuilding. so ive found a pick-a-part that will sell me a 4 barrel manifold with the matching carter therma quad still on it but im not sure about this.

so will this manifold bolt right up and drive me to work in the morning assuming i have bought a gasket kit.

will there be any major issues to deal with or anything that i would need to no. this is a 1977 318 coming off what would have to be an 88 becuase i dont think they put the carter therma quads on until 78. not sure though.

and is this carter therma quad with matching manifold worth 100 bucks?

Archer

mc -

I think you'd be better off with an aftermarket manifold and if the TQ is in good shape, or you know how to rebuild it, go for it. OK, most of the guys here will tell you the TQ is crap, but I ran one on my "slightly" modified 318 atop an Edelbrock Streetmaster for a few years and it was pretty sweet. You will need a spread bore manifold or adapter plate, (I used the latter on the SM.)

Archer

Frank the Tank

I may not be 100% correct, but the only 4bbl 318's came on police optioned cars. Therefore, if the manifold is from a 360, the ports will be of a larger rectangular shape then the intake ports on the 318 heads. I know for a fact the thermoquad was used in 74, not sure about earlier, but no later.
If you want to go a 4bbl route, get an edelbrock streetmaster/peformer intake that will closly match the 318 intake ports. I would put a holley aftermarket 2bbl on the intake that is on it, since it is actually a 2bbl carb, but with one choke tower. The 4bbl, with stock internals, will do nothing for horsepower.

Minnesota Guy

318's had 2 bbl carbs..I dont recall any 1bbls...only slant 6's had them....The later 318 truck engines could be had with 4bbl thermoquad intakes on them....with small ports.......that intake is actually a very good design. It shouldnt cost you more than 20.00 though...and thermquad carbs are 5--20.00 at any swap meet.......With a 318 and nothing to radical--ok to stick with this intake....Does a good job! But I would check ebay and pick up a cheap carter avs or afb.....They are simple--the smaller avs's can be had sometimes around 20.00....Put a 10.00 adapter on the intake since you are going from a spread bore to a square bore...and away you go!..I have been forced to drag race with thermoquad intakes..and they run great

theomahamoparguy

Thermoquads CAN be verygood but it is seriously hard to tune them. I would go with the Q-jet.(but then again I am biased to the Q-jet as I specialize in building them). Best option for a 318 would be an Eldebrock performer and the Quadrajet. You can still get tons of parts for the Q-jet. Just need to find a decent one to start with. I buy em all the time for about 7 bucks. The performer has stock port openings that are in between the the size of the 318 and the 360 there fore some port matching will be necessary but not as much as the 360 intake. I do not like the Holleys for the street. The AFB's and the Eldebrock's are a bit better but for all around driving, you cannot beat a Quadrajet.

TVLynn

At one time they made a Quadrajet as a replacement for the thermoquad

RacerHog

I think its a good deal... You will need to know if the manifold is a large port or the small port manifold. ThermoQuads work fine when they work. If you do this swap. Get the manifold carb and "all" the linkage. Your going to need it if it's a Auto Trans.
I sure the primers are enough to support that 318 motor and make it run better.
Keep us posted....

TVLynn

There were 318 Thermoquads used. Typically the lean burn system

cr 250

hey all, im going thru a mental breakdown, i just bought a 79 power wagon 1/2 ton with 360, carter t/q, have electric fuel pump on it the guy before me re plumbed it that way so using stock mech is not viable option, so i have been more than thorogh putting this pain in *** carb together, phenolic float bowl flat, no warping, x rings replaced, perfectly centered in holes, well plugs jb'd, no leaks, float level set at 29/32nds,gaskets good, demonsizzlers screw sequence performed, bought shitty mr gasket fuel reg, replaced with holley fuel reg and the f@&!in things is still showering fuel out the prim and secndry nozzles, my right hand is bleeding from punching the fender and all my rounds in my glock have been fired, ( safely in middle of nowhere and at no one lol) will someone plz help me im blowin all my $ on this thing im broke now i just hope this is not just another fruitless endeavor, any advice will be so wrlcomed

Coronet 500

I'd say you need to find a way to check fuel pressure and adjust regulator assuming it is adjustable.

cr 250

the fuel pump is producing about 9 psi, my reg goes from 4.5 to 9 tried every setting, i read the t/qs dont like much more than 5, so at 4.5 that should work, but no i aint that lucky

Coronet 500

Next would be to check/clean needle and seat.

cr 250

both are brand new, as well as new pre pump filter and post pump filter, can rule out debris getting lodged between seat and needle

RacerHog

Floats are good and not full of fuel?
Put you fuel gauge back in line. What is the running pressure at the carb? Don't believe the number setting on the regulator!!!!!! Believe the gauge.

cr 250

ok put fuel press gauge on, set fuel reg to 4.5 psi and still leaking?? wen i took floats out they were empty, aparantly they maintained there boyancy while in float bowl

RacerHog

Ok...Ether the floats are set to high or the needles and/or seats are no good.
I would try lowering the floats