Stromberg problems!

[buicksarecool]

I've got a brand new Stromberg carb on my 263. It's NOS and apparently bench adjusted to factory specs.

I've checked all the adjustments (i.e. fast idle and slow idle cam positions, choke unloader operation, etc) and everything is to spec. The only thing I'm unsure of is the choke setting as there isn't a method specified in my manual for that.

Here's what's going on:

Cold starting is no problem. Starts and idles okay. The idle set screw falls where its supposed to on the cam for the fast idle setting. It gallops a little but not too bad. That's probably a choke deal.

I think it stays on fast idle too long, but after about 5 minutes or so, it'll fall down to the slow idle setting, so that's okay.

So everything there is good. It's when the car is hot that I'm having a problem. If the car is hot and I shut it off then start it right back up again it'll fire up like a champ. However, if I shut it off and let it sit for several minutes then try and start it again it acts as if it's flooding out and has a hard time starting. A couple of times it's actually flooded out and I've had to hold the choke valve open to get it to fire again. I suspected vapor lock at first, but the carb seems to be getting a steady fuel supply and both my carb and fuel lines are cool to the touch, so I don't see how that can be the case.

I did check my throttle linkage and noticed that there wasn't enough travel to release the choke unloader. Once I adjust that it will allow me to hold the choke valve open from the pedal rather than manually holding it open, but I don't think that's the root of the flooding problem. I can't figure out why it's flooding out to begin with. Could it be the choke setting? I've checked my float level and that's good.

Anyone have any ideas?

 

[rcull]

Maybe you should look at the choke some more. Could it be after you have shut it off for only a few minutes its actually coming back on as the exhaust manifold cools a little?

Maybe you should just disconnect it for a bit and see if the hot problem persists.

 

[Jyrki]

It's probably the heat riser valve inside the manifold, under the carb, that sticks in open position. It's supposed to heat up the manifold/carb when cold, to prevent freezing, and stay shut when hot. It's operated by a bi-metal string. If it sticks open, it will overheat the carb and cause flooding.

 

[buicksarecool]

Hey thanks for the suggestions guys!

After a series of trial and errors, I found the problem. It was as I originally suspected....my choke unloader was not releasing the choke valve. It's as Bob was saying. After the car had been driven and shut off, the choke would actually cool down enough after about 10 minutes to actually close the choke valve even though the engine was still hot. So when I was trying to start the car the choke valve was completely shut, but the carb bowl was filled with gas. Gas + no air + hot engine = flooding. So I did some adjustments to where my carb linkage cam would activate the choke unloader when I floored the pedal, thus opening the choke valve and allowing me to suck in the needed air. Starts up great now. Thanks for the help!