start then stall...

[Bonnewagon]

It is on one manifold right where the head pipe bolts up. Can't remember which side the 231 uses.It is sandwiched in between. Looks like a tin can with a vacuum hose on it and with a little arm going to a lever that closes a flap shutting off exhaust flow on that side forcing it back up under the intake and carb to heat them up. It is operated by a thermal vacuum switch on the intake that lets it open at about 100' temp. On a true dual exhaust you will see only one tailpipe exhausting until the valve opens,then both work normally. Also does your air cleaner have the foil hose from the exhaust manifold to the intake? That is the THERMAC tube for heating the intake air.

 

[83cutlasssedan]

Okay thanks, I'll have a look tomorrow. Yep the Thermac is hooked up properly and works good.

 

[pontiacgp]

Yes pontiacgp, that's the modern name. I'm not old school, just old. He said after letting it warm up and he puts it in drive, it stalls, indicating a cold motor. The EFE and THERMAC are there to get intake temps up quickly. Every time I get a complaint of cold weather problems, 99% of the time those are missing or inoperative.

I'm probably older than you but I aint braggin about it...lol......that EFE valve made me some money on bets years ago cause not too many people even heard of it never mind understood what EFE meant. I don't think it's a modern name tho cause the first time I read about it was in a GM manual for a 1976 Buick that I bought for the specs on the engine I blew up...

 

[Bonnewagon]

OK, then you must remember the old style mounted in the exhaust manifold with the big counterweight and spring that allways froze up. That's a real heat riser, I call them all that out of habit. Only way to get it working was to oil it to death and whack with a big hammer. I can't count how many I've seen bailing-wired open. Anyway something I noticed reading back over all this- you said the choke flap was "allmost" closed. That may be part of it. It should be totally closed especially in cold weather. Are the rivets still on the choke housing? If so it's still set as it left the factory. If there are screws, then go ahead and loosen them a bit and with the motor cold, open the throttle to set the choke. Did the butterfly close tight? Adjust by turning the big round black disc on the housing so it does. Be carefull,it's plastic and old. Don't go past the closed position,that preloads it too much. Tighten the screws and retest. The choke should close up nice and tight, as well as place the fast idle screw on the top of the cam. Do you have a tachometer? I like the fast idle to be around 1500-2000 rpm. In very cold weather it may start as low as 1000 rpm and as the motor heats up then the rpm will rise.

 

[83cutlasssedan]

Well... played with the choke today and it's closing up tight now. I gave it two pumps to the floor and started it, and it revved right up. I haven't tried putting it into gear before it;s warmed up though, so I'm not sure if it'll stall or not. I am still planning on checking the efe valve(heat riser) but am working the next couple of days so hopefully next week. It was about 35 degrees today(2C) so I gave it the extra pump of gas before the start. My owners manual says to put the gas pedal to the floor and slowly release it then start. What do you guys do in the cold temps? What do your cars need? Just wanting to know if everything is running as it should.

 

[Bonnewagon]

By Jove I think he's got it! One pump of the pedal puts a squirt of gas into the carb and sets the choke. Any more pumps just add gas so too many can flood the motor. But when it's really cold two or even three might be needed, especially if the pump shot is weak. By the way don't feel bad about whacking the car, it happens. I was doing holeshots in my driveway and caught the pass side mirror on the fencepost. That cost me about a week of labor to fix.

 

[83cutlasssedan]

Bought a can of break cleaner today and sprayed around the base of the carburetor. On almost the first spray at the back left corner of the base of the carb I got a rise in rpm. Glad to have finally found this problem, wish i had done it sooner. I guess this could definaley create a lean condition when cold and stall the engine when I shift into gear. So how much does a carb gasket kit cost? I also have a edelbrock intake and 4bbl carb I have been planning to put on eventually. I guess this this is a good time. Not sure how big of a job this would be. Have never done this kind of removal and installation. Any tips? Thanks for your help this far.

 

[Bonnewagon]

Funny how it's usually the simple things. Just remove the carb and scrape any gasket residue off it and the manifold. Two long bolts in front,two short in back. Use a proper 5/8" flare wrench on the gas line. Hold the gas filter housing with a 1" wrench while removing gas line, and why not change filter too. Don't turn it over-gas will pour out. Don't lose the throttle cable clip!! Replace gasket and torque bolts-don't overtighten. Then go back and double-check everything you touched starting with the choke. You should be golden.