Thermoquad Issues

[GreenFish71]

Trying to diagnose and fix (2) Thermoquad issues. Hope the forum can assist and/or provide some direction.

I'm running a 340 – 4sp. Mainly stock engine. Carb was rebuilt locally about 2 years ago, after I purchased the car. Car is driven sparingly (mainly on weekends).

First issue:    Significant stumble off idle - in 1st gear.

I'm running a stock Thermoquad (#6138). The engine stumbles noticeably when attempting to accelerate in 1st from a full stop. No issues with acceleration any other gear. It is only when in 1st. I had suspected the vacuum operated secondary air valve door and made several adjustments via the choke diaphragm connector rod - door now has tension when car is fully warm and idling, but the problem persists. Before I made the adjustment there was a little bit of slack in the door, and the same stumble was present.  I'm not sure the air valve door is the problem.

I have not yet made any adjustments to the Air Valve Spring tension, but I've read this might also affect the throttle response and might be the issue with the stumble?

Accelerator pump stroke appears to be ok as I see good fuel from the main discharge.

Second Issue:    Fuel seepage. This appears to be mainly from the fuel plunger rod. Fuel seeps down the side of carb and onto throttle shaft and drips down onto the intake manifold. This happens almost every time after I shut of the car (after it's been driven). I can usually see the droplets forming around throttle shaft about 10 mins after engine shutdown. There is not a lot of fuel (maybe 1 – 2 drops form), but it is enough to smell raw fuel.

I've seen info online that this seems to be common issue related to the ethanol fuel available in pump gas, but is there an adjustment to resolve this issue short of a rebuild?  And would a rebuild solve this issue?

Any advice would be appreciated.

[Bullitt-]

  My off idle stumble was resolved by backing off the idle screw so that the Idle transition slots were square and advancing the timing to about 15-degrees BTC at idle. 
about half way down in this article 
http://www.superchevy.com/how-to/45638/

Item #2 is a transition slot

[/quote]


  Join this FB group for specific TQ info... https://www.facebook.com/groups/254276841687055

[GreenFish71]

Thank you for the information, Bullitt- !