800cfm spread bore thermoquad compatibility?

-

LovetheA's

Well-Known Member
Joined
Aug 26, 2010
Messages
827
Reaction score
117
Location
Fairfield, CT
I scored an older 800cfm aftermarket thermoquad spreadbore manual trans carb. I want to put it on my 383 with new Eddie heads and Eddie rpm performer intake. Do I need an adapter spacer to fit on the manifold?
 
Yes. Unless you put down the gasket and there is enough meat of the intake carb mounting pad to carve up with the die grinder to take that route.... if you wish to do so.
But I don’t think so.

I know you just scored the carb but I figured I say you’ll be better off and much more happy with the large primary TQ. Been there done that on a B 400.
 
Try to avoid an adapter at all cost. The RPM has the dual bolt pattern, so the TQ will physically bolt on, but the t/blades might hit the manifold. You can probably grind the carb mounting pad enough to fit the TQ. You may find that you will get an air leak
 
from the passages in the carb base. In this case, you can Devcon or JB weld the passages closed for leak free operation. I have done this many times, never a problem.
Agree, the 850 cfm might be better, but the difference will be very slight & may not be noticeable. 454 Chevs, 455 Buicks, Olds, Pont all came with QJs that are the same size of the 800 TQ.
 
@Bewy My mention of the larger one is strictly from a drivers stand point and not at wot. In my particular case I opted for the smaller primary TQ since it had the electric choke.
 
For a 383 engine, either carb size will work fine. The secondary butterflies are the same size on both the 800 and 850. Secondaries are 2.25" diameter. The primaries are slightly smaller on the 800. This works well for off throttle response. Your vehicle, your choice. If you have the 2186 Edelbrock Performer manifold, it is designed for a spread bore carb. The RPM is for a square bore carb.

Screen Shot 2021-04-10 at 4.53.41 PM.png
 
Last edited:
-
Back
Top