"Rebuilt" Thermoquad idle mixture screws have no effect.

[Geoff 2]

The 1004 is the correct gasket.

 

[Dibbons]

The 1004 is the correct gasket.

Thanks for the tip. But how do we know for sure? I know AI makes mistakes but disconcerting when conflicts with human knowledge

Per AI search:

• The SP-1003 is typically for the small bore Thermoquad.
• The SP-1004 is typically for the large bore Thermoquad.

 

[Dibbons]

I forgot to mention above that I thought I noticed a slight decrease in idle speed when I stepped on the brake pedal. I will have to plug that booster hose later to determine if that is a factor in leaning out the idle mixture (the hose connects to the rear of the intake manifold, not a carb port).

I plugged the P/B hose and it made no difference in the idle speed. Removing carb now.

 

[Geoff 2]

1004 can be used with small or large bore. 1003 should be used with small bore; it will overhang the bore in a large bore carb.

 

[Dibbons]

2 the fuel wells need tk be glued with a new glue, I use loctite marine, but there are others that are ethonal, heat and fuel resistant.
If those are leaking when you take it apart there will be a puddle under the fuel well

I did have puddles under the fuel wells. However, I turned the carb upside down a few times to drain the gasoline still inside by way of the three air vent tubes that stick out of the top of the carb before I took the three main body pieces apart.

The fuel well things that are attached with epoxy from the factory had not broken off yet. I put gasoline in both of them and waited to find leaks/seepage. It took a long time but finally with a square of toilet tissue I found a tiny bit of seepage on the passenger side. Later I tried the same procedure with alcohol and it took forever to find any seepage at all on that side. The driver side is either still sealed or seepage is even slower than the passenger side.

Based on the above, I was thinking about 'breaking' the wells off and re-gluing them. However, I might just put a thin coat of gas/oil resistent adhesive on the outside of them all put it back together for now. I mean, I could make things worse when all is said and down if I rip those guys off.

 

[Dibbons]

I am still suspecting the carb base gaskets might be a factor, being the fact that spraying brake cleaner at the front base of the carb did speed up the idle momentarily. I was not using a '72 style gasket, but rather the three piece '71 style (aluminum plate sandwiched between two gaskets).

My research found the two factory original gaskets used with the aluminum plate were asbestos, which has more flex and sponge-like qualities than the very hard/stiff paper gaskets that are currently supplied with the plate. Those black paper gaskets I used almost feel like plastic.

When I re-install the carb, going to use a different gasket, probably one of those extra thick, one-piece guys.

 

[Geoff 2]

If you spray around the t/shafts, rpm will change.