TQ question

[Monkeyed]

The two diaphragms, the one on the left doesn't hold vacuum.

What does that one do, and is there anywhere to get a new one anymore?

 

[NoCar340]

I'm pretty sure that one is an air-valve brake and can be flung without consequence. The only one you should really need is the one in the lower right of the picture, which is the choke pull-off.

 

[Monkeyed]

1 3/8" v 1 1/2" phenolic bowls

the obvious difference would be the necking down in the center of the primaries,

must be where they get the extra 50 cfm from? lower velocity, should I swap the jets from the bowls?

less obvious are the passages, above and between the primaries. the top one looks like a balance tube of some sort, not sure what the one in between is supposed to be for.. If they're necessary, I could always carefully cut them out of the gasket

 

[NoCar340]

Y'know, the float bowl I sent you came out of an early 800 I parted. The only thing that comes to mind is that someone else was in there first. I always kept all my 850s assembled except during a rebuild. If you want one that more-closely matches yours I'll go digging out at my friend's place and ship it to you.

 

[Monkeyed]

:dontknow::dontknow:

Y'know, the float bowl I sent you came out of an early 800 I parted. The only thing that comes to mind is that someone else was in there first. I always kept all my 850s assembled except during a rebuild. If you want one that more-closely matches yours I'll go digging out at my friend's place and ship it to you.

if this will still work, I'm always a fan of less restriction.

 

[8v-of-fury]

850 ftmfw.

 

[kkritsilas]

According to the Thermoquad list by Vaanth, any Themoquad can be made to work. An 850 CFM TQ on a small block (orignally came with 800 CFM) will have a less sharp throttle response at lowe/street RPM, and the a big block (originally came with 850 CFM) may not make as much horsepower at the top end with an 800 CFM. Both cases can be made to work if the TQ is tuned properly. List is here:

http://members.shaw.ca/crussel/thermoquad/tqguide.html

This note is in the Adaptations section, under the "1 3/8" vs. 1 1/2" " subsection.

in the same section, there is a note on exchanging the 3 main parts of the TQ, under the "Interchanging bases, fuel bowls, upperr bowl covers:", which may or may not have a bearing on what you are trying to do.

Kostas