David Moroney

I have a dual quad WCFB Carter setup which had no choke, so I bought the necessary kits for the RHS and LHS of the primary carb. My carbs are from a '57 Chrysler (#1306 and #1307), but I could only find Chevy choke kits.

I used the Carter WCFB service guide download found elsewhere on this forum, plus the Chevy passenger car manual to guide me.

I successfully installed the RHS with a choke tube heating the spring from the manifold. The choke opens correctly as the car warms up. All good.

The LHS was more problematic, as while all the five parts fitted, pressing the accelerator to set the fast idle and close the choke when the car is cold does not work. Nothing in the throttle linkage engages the choke kit. It seems that I might have a mismatch of Chrysler and Chevy parts that means this doesn't work?

I can manually close the choke by hand when cold, so it's not a massive problem. But I would like it to work like the manual.

Here are the photos - if these are clear enough does anyone have a suggestion?

Frankie the Fink

You have very early design WCFBs judging by the brass idle air bypass screw in the base to the right of the linkage....these carbs have slightly bigger throttle bores than Corvette carbs IIRC. In any event, is the problem that the choke plate doesn't close when you try to set it (which sets fast idle) OR the choke plate sets but no fast idle ?

If its the first problem it is probably the piston in the choke housing sticking - they get carbonized and fouled up. The second could indeed be a mismatch of hardware...or simple adjustment.

This is a picture of my numbers correct '56 Corvette carbs of the early design. Your linkage looks OK to me. Note the red circled down rod linkage angle on my carb vs yours...this is actually a pump adjustment (with a special tool) for the linkage - needle nose pliers work. ALL THESE LINKAGE ADJUSTMENTS ARE INTER-RELATED.. (see picture 3). Carefully walk back through all of your "on car" linkage adjustments in the order the manual presents them.

The second pic shows the adjustment of my choke rod at the top of the air horn via the triangular clamp - make sure that is properly positioned. Again I don't see anything wrong in your mechanism....its all about the linkage riding on that cam and the adjustments are in the book but are NOT absolute guidelines..tweaking may be required for individual cars and if carb parts were cobbled together from donors.

Compare my second pic to yours of the same area of the air horn; if I moved my choke plate to match yours that triangular clamp would have a different position (engaging the fast idle cam) than yours.

OTHER UNSOLICITED ADVICE:

Get rid of that "moonshiner's still" oil pressure hardline and get the right length or make one up....having all that piping hanging out is just an invitation to get something punctured or kinked and it will ruin your day.

Your rear carb throttle return spring is incorrectly mounted - look at my picture...if that baby comes loose - again, it will ruin your day...it looks dicey as hell to me...

David Moroney

Thanks Frankie

The problem is that neither the butterfly plate closes nor the fast idle is set, because pressing the throttle does not engage anything on the LHS choke kit. The tang on the throttle lever just moves further away from the fast idle cam.

The angle on my pump rod is more like 100° (same as the front carb), whereas yours and the manual looks more like 120°. I have bent it a little to closer to 120°, but all that has done is made the pump arm on top of the rod sit a little higher.

It seems to me the spring on the fast idle cam is too weak to pull the butterfly plate closed when cold. But I guess it has to be quite weak, to allow the thermal spring to open the choke.

Thanks also for the extra suggestions - I have moved the spring to between the throttle rods and installed a split pin as shown on your setup. I will leave the "still" for another day.

Frankie the Fink

I want to be sure you understand that the fast idle cam spring does NOT operate the choke plate; that is done by the thermostatic spring under the black choke housing in concert with the piston ***'y (in both cold and hot operation)....when you place the cover on the choke housing you MUST make sure that the tang on the choke piston engages the spring's hooked section. If it does not the choke won't set in cold weather even if you can push it closed... See red square in picture...

When properly set, and the choke housing cover screws loosened up, and holding the throttle linkage wide open, you should be able to turn the cover and see the choke plate move from open to closed and back smoothly.

The spring on the fast idle cam linkage is tensioned as the choke plate closes by the choke plate down rod so the fast idle claim engages; as the car warms up the choke plate, via the down rod, pushes down on the lever shown and the spring gradually releases the fast idle cam resulting in a less and less "fast" idle.

At the same time the choke plate closes there is a pendulum on the throttle shaft that blocks the secondary throttle valves from opening on a cold car -- called the secondary lockout "dog".

GTOguy

It also looks like the cam, with the number '203' on it, is not moving CCW enough to bump up the fast idle. In the pic with the choke plate closed, the fast idle cam is not engaged at all. Perhaps a spring tension adjustment would work here. As you know, when you hit the gas to set the choke, the thermostatic spring will close the plate, and the fast idle cam on the opposite side of the carb will drop down, setting the fast idle speed. X2 on what Frankie said about your return spring and that oil line: disasters waiting to happen, possibly at the same time! Good luck.

Frankie the Fink

OK - I was trying to stay with examples of the early design but here is my "fresh out of the box" real deal 270hp rear '61 carb OFF the car; just restored by the "Master", Bob Kunz...

Note the position of the fully closed choke plate and how ALL of the linkage is interacting and positioned. There is no question about correctness when Bob is done with things..

David Moroney

Thanks Frankie

I think the RHS choke assembly is set up correctly. The thermal spring heats up via the choke tube from the manifold, and opens the choke plate. I can also do this manually when loosening the screws on the choke cover. I have put a mark on the cover so I know where the 3/16" gap between the choke plate and housing is.

But Figure 8-C you posted worries me. To have the spring facing that direction I would have to put the cover on upside down. I have the spring tightening in a clockwise direction to open the plate.

When the car is turned off and the thermal spring cools down, the choke plate stays open. Are you saying the thermal spring should also close the plate? I thought the spring only opened the plate, not closed it also?

David Moroney

Thanks GTOguy

After bending the pump rod a little I have got more connection between the throttle lever and the fast idle cam.

My bigger problem is when I hit the accelerator peddle to set the choke plate to closed, nothing happens.

Frankie the Fink

Two pics of an original spare '63 WCFB - first choke open, second choke closed...as of 7:40am EST this morning...

You are right, Fig 8-C above is wrong for your carb, the piston and spring are flipped....I never noticed it before... I don't have C1 Corvette carbs at hand to check; maybe Chrysler and C2 carbs are reversed...

At any rate its not rocket science...do these checks on cold, non-running engine and the hot air tube can be left off.

FIRST: With the cover off move the piston's tang in whichever direction required to close the choke plate...THAT is the direction the spring hook has to pull the choke towards on a cold car..

If, when you do this things are sticky, binding or stiff you have crud in the little piston cylinder...

SECOND: If it works smoothly put the cover back on just loose enough to turn and with the throttle linkage wide open work the the cover in the direction to move the piston to set the choke - if that works the piston is good and the spring hook is set.. If that does NOT work, your spring could be broken loose from the cover (I've had it happen), or isn't hooked.

THIRD: If THAT worked then on a cold car move the cover (throttle linkage still open) so that the choke plate JUST closes with slight tension; tighten the cover in that position.

FOURTH: Pull the choke plate vertical (warmed up position) on the cold car and release the throttle linkage slowly...the choke should stay vertical. Now, blip, the throttle linkage by hand and the choke should flip forward (close). If so, all is well..

FIFTH: If the prior test fails then remove the downrod from the choke plate (the one with the triangular clamp at the air horn) completely and try the FOURTH step above again. If things now work you have a linkage problem at the base plate.

All of the above should take 8-10 minutes. Remember - car must be cold.

David Moroney

Thanks Frankie

I'm going to the local NCRS Chapter meeting tomorrow morning so will run through your procedure there with them.