I bought a custom built Thermoquad from Demonsizzler a year ago which i finally found the time to throw it on yesterday. however, i didnt get to drive it, because there were two issues:

- fuel is leaking from the primary throttle shaft
- to get the engine to idle at 800 RPM in N, i have to turn in the idle speed screw/open the primaries so far that the idle circuit is bypassed. Idle mixtures screws dont have any effect anymore.

this is my combo: 440 (8.5:1 CR), E-heads, headers, Performer intake, scott brown custom cam (.500, 280/270 ( i believe, dont have my cam card handy, 109° lobe separation). Timing is set at 19-20° initial, 38° total, vacuum advance is hooked up.

i already contacted Demonsizzler but no reply so far so i thought i might also post this on moparts to hear some thoughts. any ideas?

Fuel leaking from primary throttle shaft could be jet wells leaking. It was the problem on my TQ and scrapping the old stuff off, sanding the plastic and applying JB weld sealed them up good.

Your idle issues are common for a TQ and running a larger than stock cam. You'll get plenty of ideas from the Moparts crowd.

I opted for the primitive approach of drilling holes in the primary throttle blades on mine.

where would the jet wells be located?

below the jets. the fuel can settle and corode. sometimes you can patch it up.

run through
http://oldcarmanualproject.com/manuals/Carbs/Carter/Thermoquad/1972/index.htm

TQ's arent cool. they work. but not cool.

Could also be the O-rings between the cover and the body that are not sealing right??

how does a AVS compare to a TQ ?

the TQ has one spring and a balance rod system , which is kind of cool. it might even help. the 2 stage accel pump looks like fun.

the AVS has one springed rod per primary(2). "cool" . the secondary doors open mechanically. the pump shot feeds longer?

..Have you taken the carb off?

Checked the jet wells in the plastic mid section?

The jet wells are the two plastic "protusions" that stick out from the bottom of the plastic bowl section.

To see them.....You have to break the carb down to the three main sections -

Top plate, plastic bowl and base plate.


If you're not confident to do this - I suggest you keep trying Dave.......

-
If you do get the Carb apart -

Take the plastic fuel bowl mid-section

(AFTER DRYING THE BASE) - Fill the float bowls with fuel and rest the whole thing on some paper towel or newspaper

To check if the two fuel wells leak - Look for fuel staining on the paper under the two "protrusions" that the bowl was resting on .

If there is leakage, thats you problem.

REASON - (The epoxy thats used to attach the protruding wells to the bowl base gets dry and cracks - this causes leakage.

They have to be removed and re-attached as per the earlier post.)

NEXT - The fuel wells (protusions) also have a rubber O-ring seated inside them from the top...be careful not to lose them if you turn the float bowl section upside down.

If they are not there - then its them thats the problem,

REASON- ( if the o rings aren't located in the wells - fuel escapes out of the welss and into the venturis - it causes the motor to flood.)

thanks, that did help! I will take it apart ASAP and will let you know!
Best regards,
Michail

Beside the epoxy glue as a weak point on TQ bowl, then the area where attaches the jet wells ( just right where the epoxy glue is ) are the weakest, since that is the thinner plastic wall of all the bowl and is the more exposed to heat, getting inside a cradles on lower plate.

I tipically make a test over that area. Is some risky but if breaks easily you located if problem is on epoxy or on bowl itself. Gently hit with a rubber pad or hammer ( I have used a regular hammer too LOL ) at a side ( I would suggest make it on both sides ) of each glued wells. If wells came out complete without broke anything, then the problem was the epoxy. if came out with parts of the bowl, then the part was ready to broke completelly and you had already the leak there.

If broke the area where the bottom wells glue, can it be repaired, rebuilding with more epoxy glue to refill the broken area around, BUT is not a guarantee anyway. I have made those broken bowls back to road, but never in a perfect conditions... just enough to ride pretty decent.

another breaking point are the holes/ducts to rear bolts, specially the outer ones. sometimes are fixable, sometimes not.

call him on the telephone. He is very busy
and doesn't get a chance to check his E-mail. I usually call him between 8:00 and 9:00 est.