Engine won't idle - What else to try?

[So Cal Mark]

when you state the idle screw is all of the way in, are you talking about the mixture screw or speed screw? The mixture screw should be out a couple of turns to start with, then adjusted with the engine warm and idling. I'd back the speed screw all of the way out and ensure the throttle is completely closed. A small vacuum leak won't cause the trouble you're describing, it would have to be a massive vacuum leak

[mdrburchette]

You might also want to make sure your jets are clean. Debris can cause a problem with adjusting.

[bobcity]

Sorry speed screw is all the way in, in order to start or run when cold, with linkage disengaged.

Mixture screw must be at least 4 turns out to run when warm.

Bottom line is:
Won't idle or run below 2000 when cold. When fully warm and both screws adjusted to the best I can do, I get 1500 to 1000 back and forth. And bad hesitation when starting to accelerate.

Take out the jet and check it is now on my list to try. Thanks

[So Cal Mark]

are these the same symptoms as the old carb? When you did the cyl balance was it running above 2k rpm or idling?
When it's at 1000 and surging, will it smooth out if you gradually close the choke plate?

[bobcity]

are these the same symptoms as the old carb? When you did the cyl balance was it running above 2k rpm or idling?
When it's at 1000 and surging, will it smooth out if you gradually close the choke plate?

This is now the old carb. I was somewhat desperate to get the car running as I need to take is somewhere for an insurance claim. The last time I actually drove it, it was parked when someone I knew backed right into the front RT fender.

So to answer Mark, It does smooth out a little when I close the choke a little. I've got the EGR closed off.

The car is running so poorly right now that I think maybe it's blow a head gasket. It runs real ruff below 2000, It sounds like it's only running on 3 cylinders but balance test doesn't prove it. It just can't keep getting worse every time I try it. Unless the plugs are just fouled from so much sitting and reving. Could that be part of the problem? I'd better pull the plugs tomorrow and check them.

Also, to answer someones suggestion: I re plumbed all the small vacuum lines from carb to collector or whatever you call it, according to the manual and the color coding. The old plastic lines were disintegrating and not going where they were intended.

[So Cal Mark]

at this point you need to check the basics; compression, cam timing, firing order, spark plug condition. It sounds like you have more than a carb issue. If the engine runs that rough, you have at least one cylinder not firing

[Jim DeShon]

Yup ! That was the point I was trying to make previously. If you don't see your problem in the carburation, look somewhere else. ...J.D.

[bobcity]

at this point you need to check the basics; compression, cam timing, firing order, spark plug condition. It sounds like you have more than a carb issue. If the engine runs that rough, you have at least one cylinder not firing

So far ... 3 beautiful plugs and one black with carbon.

The checking continues.

[rlux4]

Have you checked that the spark is getting to that bad plug? Put that spark plug wire on a good plug and ground the plug to the engine, see if you get a good spark. If it's good, check that cylinder for compression.
Ron

[bobcity]

Cyl #1 130 dry 150 wet
#2 120 dry 120 wet
#3 100 dry 130 wet
#4 120 dry 130 wet

So, when I screwed the tester into number 3 I noticed that it was hard to get it to tighten and probably accounted for the low number, hum.

When I'd finished I went to put the plugs back and guess what. Number 3 would not tighten. It is stripped in such a way that it will screw in forever and not tighten. Expletive deleted.

So I got out some permatex ATV and coated plug and screwed in. I don't expect much from this, if anything. It would be nice if it held long enough to see if this is the problem. Waiting for it to dry.

Can someone offer any ideas about a fix for this. Do I have to pull the manifold? I'm thinking this is pretty serious.

Also, could this be the air leak or cause of no idle/racing and if so, why was plug so clean?

I know it is not the reason number 4 plug was fouled. but that was a very recent addition to the list of problems, and I will check separately as suggested by Ron. Checked resistance of plug wires too. They were OK.

Thanks,
Bob

[bobcity]

Er, I meant pull the head not manifold. Getting dingy.

[rlux4]

You can "repair" the plug threads without pulling the head. Get a helicoil kit and you're good to go. I've heard of people that have used it and it lasted the life of the car.
Ron

[So Cal Mark]

helicoils can be installed without pulling the head. You have to be careful to get all of the chips and debris out of the cylinder though. A good trick is to coat the drill bit and tap with grease, so the chips stick to them.
The stripped plug won't cause a vacuum leak, only a compression loss

[rlux4]

I love this fourm! Mark, that trick is a new one to me. It makes perfect sense, maybe that's why I never thought of it before.
Ron

[So Cal Mark]

man, I should be selling these tips!