BlueCalais79

I know this is our Olds site, but I'll bet this problem runs all throughout these motors regardless of make.. I've got a 69 Camaro, 250 4.1 6 cylinder. When I come to a stop in a forward motion, the car stalls out. Every time. It always re-starts and idles fine. I can keep it in neutral and rev it just before stopping and it won't cut out but left footed braking won't help in a panic stop. When I back up and stop, no issue at all no stalling. When I move forward and stop while turning sharply left or sharply right, no stalling. This car has no power steering or power brakes.

This motor has the 1 barrel Rochester monojet. I replaced the carb, no difference. I also replaced the fuel pump, fuel line from pump to carb, pcv hose, no luck. New coil, new wires-cap-points-condenser. No luck here either.

Would anyone have any additional ideas, I'm out of alternatives, other than trying yet another carb.

Thanks.

People are telling me the carb float is off, but on 2 different carbs? Doesn't seem likely but it is possible.

rocketraider

First, kudos for leaving the 6 in it. There are few of those left and if it ever leaves your hands odds are within a month there'd be a big-block in it. Camaro guys' eyes glaze over and they develop an uncontrollable tic if they see a six underhood. Not a joke-I've seen two of them do that.

Is this an automatic or stick shift? Also what smog equipment does it have, specifically the smog pump?

1st check idle speed. Should be at least 550 rpm. Try bumping it up 50 rpm and see if things improve. Also use a vacuum gage to set the idle MIXTURE screw. Aim for the highest vacuum reading you can get.

2nd if the carb has an idle speed dashpot make sure it's functioning. If it's weak or off adjustment it can let the throttle close too quickly which can cause stalling.

3rd check dwell and timing, and make sure the distributor's mechanical and vacuum advance are functioning. Sniff around for vacuum leaks though that will usually cause a rough idle if it will idle at all.

4th make sure the PCV system is clean and functioning.

Last resort tear down the carb and rebuild it. It's been 40+ years since I touched a MonoJet but it's as simple a carb as you'll ever find. Yes it is possible to get a bad jobber rebuilt carb out of the box. If you still have the original that's the one to rebuild.

Good luck.

BlueCalais79

Thanks, this will stay a 6 as long as we own it. Long story short, the car started out as a 3 on the tree and was converted to an automatic in 1976. We reverted it back to a Saginaw 3 speed manual in 2017 but put the shifter on the floor. There are no air/smog gizmos on this car, fortunately. It does have an idle speed solenoid that I do not believe is original to the car and I don't believe it is working properly. I'd like to ditch that solenoid and use the wire for an electric choke as the Divorced choke does not work properly.

rocketraider

Those were the beginning years of smog equipment. In your case the solenoid would have been installed to close off throttle plates completely when the engine was shut off to prevent dieseling.

It also controls idle speed. The solenoid's plunger extends and contacts the idle speed arm when energized and screwing the plunger in and out is how you adjust running curb idle speed.

Quick solenoid test. Hit it with straight 12v and see what the plunger does. It should extend and then retract when voltage is interrupted. Do this several times. If it's not working or if it won't repeat, shoot a little WD40 or other light cleaner/lube in it, and clean the terminals in its plug. If it still won't work, unplug it and take it out of the picture, even remove it if you want. Then use the idle speed screw that's actually mounted to the carb body to set running curb idle speed.

Solenoids and dashpots. Used for smog equipment, to raise idle speed with A/C on, to slow throttle closing, who knows what else. Useful things but can confuse you if you're not 100% sure what its intended function is.

A six-cylinder 3-speed column shift Camaro. Does it by chance have a bench seat? I have seen exactly one so equipped. It got into the wrong hands in 1979 and now parades around as a Z/28 complete with a 396🙄.

Given GM's notoriously flaky column shift linkage, converting to floor shift isn't a sin. Back when column shifted 3 speeds were common, a good garage would clean and lube the shifter plates as part of an oil change and lube service. As they became less common, that service disappeared.

Koda

I think you have classic low idle that is barely keeping the engine running. Try taking it out of gear and letting off the clutch way before a stop and see if the engine dies, and stop normally with brakes. I think your idle is not sufficient and the load coming to a stop could well depress it below idle and it just doesn't recover. This is fixable as outlined above. Reverse is a much lower gear than even first, let alone top gear.

That solenoid is an electrically presented minimum idle stop, like said.

Supernice88

Curious, Did the problem start after the shift conversion?

BlueCalais79

This issue started with the start of the driving season this year, unfortunately. I started out thinking the gas went bad but I've since added in a sufficient amount of fresh gas to rule that out as a cause. The car's been a manual now for 4 years. I did try taking it out of gear and letting off the clutch a long way before a stop to see if the engine dies and it continues to idle, and as soon as I use the brakes it cuts out. The harder I brake it the quicker it stalls out. Meaning, if I brake slow or really slow, sometimes I can get it to keep running. You know, using the classic left foot braking technique we all learned how to do way back in the day when our cars always died for whatever reason. At a full stop it starts right up and stays running. No issues there.

rocketraider

If the solenoid is working correctly and idle speed isn't too low, it sounds a lot like a low float level that's so low that fuel slosh while decelerating actually uncovers the main jet.

Even with fresh fuel, that old gas tends to leave lingering effects. A sticking or loaded float is one of them.

Time to tear down, thoroughly clean and rebuild. As I said before, if you still have the original carb that's the one to rebuild.

Can you get non-ethanol gas where you are?

BlueCalais79

Will do, I'm looking into rebuild kit parts from Mikes Carburetors, including a brass float. For me, Ethanol-Free gas is available in Upstate NY (route 22 above the Mass. Pike), and/or Vermont. Connecticut has no stations available unless you buy race fuel, and I have not seen any at all in MA.

Fortunately the Ethanol Free gas in NY is 90 Octane. It fits the bill, I always make it a point to grab 10 gallons in cans when we go there, in addition to filling up the tank with it.

rocketraider

Mike's should have an electric choke kit that will work for you too. Make sure to look up Joe P's tutorials on installing and wiring those thru an oil pressure switch.

Is the divorced choke coil not working at all or simply misadjusted?

BlueCalais79

Heck, I have a ready made live wire, I'm going to dump the Idle Solenoid and use that wire for the electric choke. Makes it a plug & play.

The screw/bolt or whatever it was at the top of the divorced choke that goes into the intake manifold is now one and the same. It is a melded rusted rounded off mess that was like that when we got the car 10 years ago. The original choke rotted off. I bought an NOS unit but at the top there is nothing to attach it firmly to so as a result it's just held on by the bottom bolt which itself is ready to be of no use. I have an NOS Intake manifold but that's not a job I'm looking to do unless we get the whole motor redone.

So, an electric choke really fits the bill here. Right now it will not close and I have to pop the hood and pull the rod up when I initially start it.

joenywf64

NOWHERE IS IT MENTIONED IF THIS GUY CHANGED THE FUEL FILTER INSIDE THE CARB! MINE WAS RUNNING TERRIBLE & STALLING OUT. I PULLED THE FILTER & IT LOOKED GOOD ON THE OUTSIDE, BUT DIRTY ON INSIDE WHEN I CUT IT OPEN! With new cheap filter - runs perfect.
Too bad this car also isn't an RS with either 6 cyl ! I have a '68 RS with a 250 6 cyl & a glide, but no bench seat.
I have NEVER seen a '69 RS with either 6 cyl, & i bet no one here has ever seen 1 either! Few people knew/know such a combo could be ordered from the factory.
Rarer than a '69 ZL1, if you ask me!!

Sugar Bear

Check everything already mentioned plus the intake manifold gasket for vacuum leaks. It was a problem area.