Originally Posted By: Blackwater
I know you know this, but look for vacuum leaks!!

It looks fabulous!!

Thanks Blackwater . . . no vacuum leaks as the carbs contain all fresh or NOS gaskets that are well fitting . . .

Originally Posted By: Beater of the Pack
I hope you figure it out and I hope it is easy to fix.


Thanks Beater . . . and the answers are yes and no! Do you remember the old David Letterman "stupid human tricks" segments?

These Carters have some really trick 'automatic' features built into them to enhance driveablity . . . but the engineers at Carter never intended them to be run in pairs.

My runaway idle issue was due to the fast idle cam stops.

There are two screws controlling idle on a Carter WCD - the throttle stop screw and fast idle stop screw. When the carb is fully warmed up the former controls idle RPM. During cold-to-warm operation the latter controls a higher RPM that literally walks down the fast idle cam as the auto choke springs heat up. Very neat.

My runaway revving issue was in fact a stupid human trick. When I would clear the front carb off the fast idle cam stop (to close the throttles) the rear fast idle cam stop would engage. With a solid linkage between the two carbs either stop screw holds both throttles open. Duh!

I am currently noodling on how to synchronize these fast idle settings. I cannot simply disengage one and use the other to govern both throttle plate openings.

The reason being that the Carter engineers designed the fast idle system to govern both the throttle and the choke plate:


When the engine is running on a fast idle cam stop the choke is controlled by the choke control rod - regardless of how warm the auto choke springs may be.

I have moved fast-idle syncro to the back burner for now.

By managing the warm-up to operating temperature I have managed to get the engine to settle down to ~1200 to ~1500 RPM.

I am now on a teeter-totter between initial timing and throttle plate opening. The engine seems to prefer spark advance - but then hates being throttled - popping and rapping the exhaust pipes. Back off the initial timing and the RPM comes down into a rough rich idle that leads to stall . . .

The good news is that I am trying to wrest control of a running engine . . . a much better place then trying to figure out an engine that won't run :-)