"Black plastic cup filled the cavity from the '75 type apt". Page 12

[GSP7]

On my 17080213 carb im rebuilding

Am I supposed to have the black plastic cup insert installed as seen and on page 12 of Cliff"s book

This ebay bought, previously rebuilt carb did not have a plastic cup in there when I disassembled it. Maybe this year carb doesnt use need that plastic cup?


(Plastic cup would be located in the round area under where the yellow pencil is laying across, shown on page 12)

[GSP7]

I dont see the round plastic insert part on Cliffs parts site.

Cliff do you have that piece, so I can add to my parts order?

[Kenth]

Early M4 Qjets often had the cup insert, later on it was omitted from factory. Not needed.

[Cliff Ruggles]

I agree and don't use it in my own carburetors.

However, I've had customers complain over the years that leaving it out caused brief flooding with really hard braking.

I've never experienced that and drag raced and street drove my Ventura for nearly 40 years with five different engines in it and no cup in the aneroid location on my 1977 Pontiac Q-jet......FWIW

[Cadman-iac]

I agree and don't use it in my own carburetors.

However, I've had customers complain over the years that leaving it out caused brief flooding with really hard braking.

I've never experienced that and drag raced and street drove my Ventura for nearly 40 years with five different engines in it and no cup in the aneroid location on my 1977 Pontiac Q-jet......FWIW

 Does leaving this out give you much more bowl volume, or does it even make a difference?
 Wouldn't it make it easier for fuel to get to the bowl vent passage with this missing since the gasket has a cutout in this location on models that have the bowl vent?

[Cliff Ruggles]

Increasing bowl volume is a complete waste of time and funds. 

The size of the fuel bowl (despite what you read anywhere on the Internet) has absolutely NOTHING to do with engine performance or using any carburetor in a high performance application.

The key to success here is to make sure the bowl is FULL at ALL TIMES.

This is easy to accomplish, even with a Q-jet.  Just make sure you are using the correct fuel inlet seat diameter for the power level and potential performance of the vehicle AND that the fuel delivery system is up to the task.

Hope this helps some.....