surging idle, has to be something simple

[77 350 Shorty Wide]

Sorry... checked again and saw that you had!

Terry

[77 350 Shorty Wide]

Have you checked the valve lash? Or maybe they are sticking possible the dreaded flat lobe or lobes on the cam that seems to be such a big problem these days.

Terry

[78ak]

couple more pics of the beauty - she will run again.

[77 350 Shorty Wide]

Have you tried plugging the vacuum line the the brake booster? Do you have power brakes? Maybe a leaking diaphragm inside the booster?

OK see you do have power brakes...

[78ak]

I unplugged the booster and went through that process, old and rusty but no vac leak

[78ak]

compression test shows number 1 at 140, #3, 5, & 7 between 130-140, #2 at 127lbs, #4, 6 & 8 between 128-131

checked cold, haven't ran it for a few days, and its 20 degrees outside

not bad.

I'm thinking carb at this point, can't think of anything else it could be. same problem as the beginning, idles fine, put it into gear, it dies.

[donut]

I'd plan on going through the carb out of general principle at this point. When it starts running rough, any smoke? Mine would throw black smoke when it was loading up at idle.
Crud and deposits can/do build up internal to the carb, float could have a pinhole (or not be alcohol friendly) and sinking, junk could be laying on the seat assembly holding needle open, choke could be slamming shut... For the choke, you can unplug the elect connector and use a bread tie or something to make sure it stays open.

I've cleaned out enough over the years, that I don't order a kit. Though I do source one in case I tear a gasket or the needle has the rubber rotted of it.

Once this is done, then go back through and check all the vacuum lines. Pull and visually check, not spray and hope. I've found a few that spray checked out fine, but were busted, didn't show up until they were moved.
Then move on to the ignition. Slow and methodical, ruling out things as you go.

Another thing to check, stock exhaust with the flappers right off the manifolds? One of these could be stuck shut and blocking the exhaust flow.

[78ak]

white smoke while choke is on, then it drops RPM after warm up and white smoke stops, no smoke after warm up. I'll recheck vacuum lines by looking instead of carb cleaner.

this is what it does right now:
starts up, choke is on, high idle that sounds normal for a choke, runs good, warms up, drops rpm to normal warm up rpm, runs good, no/minimal miss, get in and put foot on brake, drop down to reverse or drive, sputters for 1 second then dies.

new theory....torque converter instead of carb

[cadillac_al]

It sounds like severely low vacuum or a carb issue. I would verify vacuum before touching the torque converter. It sounds like it is less than 15.

[78ak]

I think you're dead on. Going back to square 1 - I'm going to pull every damn vacuum line off this time and check, might replace a few also. It can't be torque converter. Last night I went out around 10:00 pm as I had a thought it might be the exhaust flapper - I remembered it was rusted and stuck, thought it might be stuck closed... that wasn't it. Has to be vacuum.

[donut]

Kinda glad I lost what I typed, lol.
Agree with the vacuum. BTW, you on ported (part time) or manifold vacuum? When you set the timing, did you disconnect the line off the vacuum can and plug it?
last is a simple mistake, but can make a big difference.

You set the timing, what are you set at? Was the tdc line (on the balancer) verified first?

[50seven]

I would check that the egr valve is not sticking or stuck open completely. if it is stuck open it is just one big vacuum leak. try plugging off the egr, cleaning it out or replacing it.

maybe plug off all the vacuum lines to the carb and go thru each one by one checking for leaks.

[77 350 Shorty Wide]

Good Morning, Is your "white smoke" at start up truly smoke or steam from condensation burn off? Maybe unrelated to your problem but interesting anyway. I know this is coming from someone not in the complete know about such things but what about the vacuum modulator on the transmission having something to do with this????

God Bless, Terry

[donut]

I assumed white smoke was condensation because it stopped once warmed up

[78ak]

I don't have an ERG valve, no smog stuff on this motor. The white smoke is only at start-up -- it may be condensation, but it sure stinks to hog heaven like thick exhaust. I also noticed as I'm under the hood that it seems like I have an exhaust leak somewhere, smell is bad - and I noticed it slightly as I drove down the road that the cab has an exhaust smell.

getting back in it this weekend to check vacuum hoses

[78ak]

good idea on the vac modulator. I checked the hose attached to it for a leak using carb cleaner, but I'll pull it off and look a little closer this time. It shifts fine, though, so guessing the actual modulator is still good.

[geezer#99]

Considering the temperature where you live, how does it run after you've driven it for a mile?

[78ak]

if I stomp on it, it hesitates for only a split second, then takes off -- if I'm in 3rd, stomp, it'll drop to 2nd nicely and engage back up to 3rd like it should. I noticed one time that I had it in 3rd, going pretty fast, somewhere around 65mph, stomped on it and after a second it started bogging down like it was starving for fuel. Just normal driving, like 45 mph, and give it a little gas to get to 60 or so, it sounds like almost like an exhaust leak happening, tick tick tick, sounding almost like headers leaking.

[geezer#99]

I'll clarify my Q!!
After you start it, warm it up, it quits when you put it in gear, you restart and drive away, how does it run or idle after you've driven it for a couple miles.
Does it still want to die at the first stop?
Does it get better and idle without quitting?

[rich weyand]

That tick-tick-tick under acceleration is probably just header slap. Headers are very thin, and what you are hearing is the exhaust pulse hitting the corner in one of the tubes that bends sharply right out of the head. The Hooker 2453 headers made for the K trucks do that on cylinders 5 and 6.

[78ak]

after driving for a while and coming to a stop, it will die, but sometimes it won't die all the way, it just idles very rough and at such a low rpm it wants to die

[78ak]

I don't have headers on it, but I was saying the tick tick is the same sound as a header leak

[geezer#99]

Originally Posted by 78ak

after driving for a while and coming to a stop, it will die, but sometimes it won't die all the way, it just idles very rough and at such a low rpm it wants to die

While your heat riser might be working, there's a good possibility the crossover under your intake is plugged not allowing any heat to warm and keep warm your intake plenum. It runs rough because the fuel puddles in the plenum and you run lean.

[rich weyand]

Ah. If you don't have headers, then it probably is an exhaust leak.

Here's a thought. Check to see if the vacuum advance is sticking. When it's idling rough, put a timing light on it. Do you see the base timing you set with the vacuum advance disconnected, or do you see something like your base timing plus 15 degrees more?

If you see base timing, then the vacuum advance is sticking -- i.e., not pulling in. That could cause your symptoms.

[Dead Parrot]

Chased an exhaust leak on an old Camaro for a while. Symptoms like yours. Turned out to be a small leak in the fuel pump. Was slow enough that a warm pump would be dry. Replaced the pump, no more bad 'exhaust' smell. Make sure your exhaust leak isn't a slow fuel leak.