Let's figure out this choke issue...

['74 Sport]

... on a Carter BBD. I've set all the carb adjustments as best I can, according to the rebuild kit instructions and the literature Dan provided in another thread. When warmed up, the engine idles nicely and runs great at low or high speed. It's just a booger to start cold. I fully believe it is the choke or choke pull off settings.

The choke mounted to the exhaust manifold pocket COMPLETELY closes the choke plate when on the high lobe of the fast idle cam. Should it do that, or should there be a slight opening for initial starting? I know that once the engine starts and creates vacuum, the choke pull off will open the choke plate to a gap distance I set with a gauge. I'm just wondering about the initial choke position.

 

[RedFish]

The heigth of the choke heater rod could be wrong, especially if thickness of the carb base gasket changed.

 

['74 Sport]

That's easy enough to adjust with a little bending here and there. I need to know if the initial cold start-up requires the choke plate to be 100% closed, or should it have a pre-set gap. In other words, with the plate completely closed, the only air getting in to mix with the initial shot of fuel is that which can enter through a small round hole in the choke plate. Doesn't seem like enough.

I can play with various combinations, but I was hoping someone could tell me how theirs is set up.

 

[RedFish]

I'd try about 1/8" initial gap. I dont like to close the baffle all the way simply because they can stick there. Part of your hard start issue may be in initial timming too. Everyone performance minded will recommned up to 18 degrees initial timing but.. that doesn't help cold starting. Chryslers use gear reduction starter that is slower operating than others.

 

[TLlew]

I had the exact same problem on my /6. The spring in the choke termostat was way too loose. I adjusted it for about an 1/8" gap like RedFish said and now it starts much easier and runs great cold.

 

['74 Sport]

The choke plate is completely closed with the engine cold and the fast idle screw sitting on the high lobe of the plastic cam - good so far.

Pushing the choke rod back all the way (like it would be with a warmed engine), the choke plate is fully open - like you would expect, right?

Uh, oh! Notice what is happening at the high speed cam/screw? That's right, nothing. I have been told as the engine warms and the choke begins to pull the plate open, the link rod on the cam should slowly rotate it so that the high speed screw drops to the second step and then subsequently continues to lower the rpm as the plate opens more. Finally, when the engine is completely warmed to the point where the plate is fully open, the link rod has rotated the cam off the fast idle screw and the curb idle screw then maintains engine idle.

See in the second pic how the choke plate is fully open but the link rod to the cam has just made contact with the top of the slit in the choke plate's shaft? And the high speed screw remains on the high lobe? Further, you can see in the third pic where the cam is rotated off the high speed screw, but the cam link rod isn't even making contact with the top of the slit in the choke plate's shaft.

Shouldn't the link rod be adjusted so that as the choke opens, the rod contacts the top of the slit and begins to apply pressure to the cam? Then, as the plate opens farther, the cam is rotated to affect the high speed and curb idle screws?

Anyone have time to confirm what their Carter BBD does through the choke/warm up cycle?

 

[RedFish]

I've owned only 2 carbs in my life that would drop out of high idle on their own. That requires the perfect angle to the steps,and screw tip, spring pressure, etc...

 

[-Po]

I got some problems with my choke, 1 bbl holley, 225 \6.
It starts pretty easy when its cold, but when I give it a little gas, the choke disappears completely, so it dies out if I dont hold my foot on the gas when its cold\warming up. Anyone know what this can be?

Sorry to impose on your thread `74 Sport, but I though it would be smart to collect some choke problems, instead of a new thead everytime.

-Po