DeTomaso Mailing List: July 97, Message #199
     



From: "D.Jones" <m203253@ws2200.mdc.com>

Subject: Re:Carter Thermoquad

Date: Fri, 11 Jul 1997 11:32:34 CDT



> Be carefull when using the Thermo Quad.  Many used ones have the plastic

> middle section warped.  Once they warp they are trash.  The owners manual to

> our old chrystler said if the indicated rebuild procedures did not fix the

> problems then discard the carb.  That is what we had to do with ours.



I've seen rebuild kits advertised that contain the center section.

BTW, the center section is not really plastic.  It's a phenolic resin

compressed wood product.  The reason they picked that material is

that it's a superior heat insulator.  



The guy who turned me onto to Thermoquads seems to think the warpage 

is fairly rare.  He claims that stripped bolts are more common but 

then you've got that problem with aluminum too.  



> Personally I prefer the AFB.



The AFB is a pretty good carb, not quite as sophisticated as a Thermoquad

or Qjet but much better than a Holley.  I run the Edelbrock 750 AFB clone 

on the 351C in my '66 Mustang.  I have one little gripe with it.  The 

secondary air valve is counterbalanced by weight and isn't easily adjustable 

like the spring loaded air valves employed on Thermoquads and Qjets.

Edelbrock should have cloned the Carter AVS instead of the AFB.  The AVS

was a refinement on the AFB and is very similar except it uses a spring 

loaded air valve.  Now that the car is a 5 speed, it's not a problem but, 

when it was an automatic with a high stall converter, I could fool the

air valve by flashing the converter off the line.



For those of you who aren't familiar with Carter carb nomenclature, the 

air valve is a flapper door that resides over the mechanically actuated 

secondaries.  It's counterbalanced with a spring or weights so that it

progressively opens in response to engine demand for airflow.  This

arrangement avoids the secondary bog associated with Holleys because the

secondaries only operate when there is sufficient airflow.  On the AFB

the air valve is a flat plate but on the Thermoquad it's shaped to 

enhance the variable venturi effect.  This is a great arrangement for 

the street though, in all out competition, the flapper door is an airflow 

restriction.



BTW, I'm looking for a couple of 400 CFM Carter AFB's (9400 series)

for a dual quad installation.  I'd appreciate any leads.



Thanks,

Dan Jones



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