idle?

[barbee6043]

76 Volare roadrunner 318, bbd carter 2 bbl, auto stock everything I figure Mileage reads 95,000, I guess 195,000. Have no idea it has ever been apart.
I can not get a constant idle anymore. Warmed up, ran great till recently. I did put a new fuel pump and filter on it. Warmed up, if I put it in gear the rpm drops from 8-900 to 400 and wants to die, Driving down the road, I slow down and it dies.
After warmed up, I noticed I can close the choke butterfly a little and the idle speeds way up. I cannot find any vacuum leaks, just a very slight one at the throttle shaft. I sprayed carb cleaner in the PCV valve.

I had a 318 once that the timing chain was plenty loose and would die at a stop sign. Timing would get out.
Is this a carb issue or what??

 

[AJ/FormS]

EGR stuck open?

Put a vacuum gauge on the dipstick tube , flip the PCV out of the grommet and seal both valve covers. If the engine doesn't make pressure almost instantly at 900 rpm, something is wrong. If it pulls a vacuum, the intake gaskets are blown out into the valley, and you should be seeing oil in the tailpipe.

If you have a brake booster, clamp the line and note any rpm change.

Put a timing lite on it and note any timing change going into gear. At 900 rpm the mechanical advance may already have started. Make sure the Vcan is on the spark-port and is not commanding advance at 900 rpm

If nothing turns up, pull the carb off and look for a crack from atmosphere to either port thru the carb platform. I guess check the base gasket is correct for the application, and correctly installed.

If you have a lean burn, make sure the plumbing to it is 100%. If the ECU senses low vacuum it might think the car is working and pull timing. The Vcan should not receive vacuum until the thermo-sensors warm up and relay it. The sensors must be sitting in liquid to properly trigger. On early systems ( I don't know the years), the Ecu was tied to the transmission and no advance was allowed until the trans shifted into hi.
Once all the hoops are jumped thru and the vacuum is "normal", then the Vcan works "normally".
I don't know all the ins and outs of the lean-burn system, as I only ever worked on a few of them. Up here we didn't get LB until the '80s; but this I know; if you pinch the line to the Can, you will not get any advance,lol.

 

[TrailBeast]

76 Volare roadrunner 318, bbd carter 2 bbl, auto stock everything I figure Mileage reads 95,000, I guess 195,000. Have no idea it has ever been apart.
I can not get a constant idle anymore. Warmed up, ran great till recently. I did put a new fuel pump and filter on it. Warmed up, if I put it in gear the rpm drops from 8-900 to 400 and wants to die, Driving down the road, I slow down and it dies.
After warmed up, I noticed I can close the choke butterfly a little and the idle speeds way up. I cannot find any vacuum leaks, just a very slight one at the throttle shaft. I sprayed carb cleaner in the PCV valve.

I had a 318 once that the timing chain was plenty loose and would die at a stop sign. Timing would get out.
Is this a carb issue or what??

If you don't have any vacuum leaks then the fact that you close the choke a little and it speeds up points to junk in the idle circuit.
Here's what I do very first thing when I run across this scenario.

Turn your idle screws in all the way counting the turns it takes to bottom them out lightly.
Pull both screws and shoot each hole with a healthy shot of WD, PB Blaster or whatever you have laying around. (what it is does not really matter)
Then hit each hole with a good shot of compressed air.

Put your idle screws back in and bottom them out lightly again, the count the turns backing them out until you are at about the same turns they were.

This does it pretty much every time.

When you change pumps or even filters there is almost always something that breaks loose and ends up in the bottom of the float bowl/s and gets into the idle circuits.
The fluid sprayed in them before the air shot helps to carry the junk out of them.

This is easy to do and like I said, it works really well.

 

[barbee6043]

If you don't have any vacuum leaks then the fact that you close the choke a little and it speeds up points to junk in the idle circuit.
Here's what I do very first thing when I run across this scenario.

Turn your idle screws in all the way counting the turns it takes to bottom them out lightly.
Pull both screws and shoot each hole with a healthy shot of WD, PB Blaster or whatever you have laying around. (what it is does not really matter)
Then hit each hole with a good shot of compressed air.

Put your idle screws back in and bottom them out lightly again, the count the turns backing them out until you are at about the same turns they were.

This does it pretty much every time.

When you change pumps or even filters there is almost always something that breaks loose and ends up in the bottom of the float bowl/s and gets into the idle circuits.
The fluid sprayed in them before the air shot helps to carry the junk out of them.

This is easy to do and like I said, it works really well.

I did all that before I changed the pump/filter but I can do it again. Idle circuit is what I figured but that probable slack timing chain I can see being a problem but not at idle.
I hate buying a remamed carb as that has always been a crapshoot, I rather find a member here that just took off a GOOD working Carter 2 bbl and is changing over to a 4 bbl. I thought about changing to a 4 bbl,also,. I have 2 625cfm used carbs, but need the intake. My carbs are no telling what condition!!
I still remember the good old days when I could take a core to my good machine shop and have a quality rebuild! Buy a new Edelbrock and BOOM!!

 

[TrailBeast]

I did all that before I changed the pump/filter but I can do it again. Idle circuit is what I figured but that probable slack timing chain I can see being a problem but not at idle.
I hate buying a remamed carb as that has always been a crapshoot, I rather find a member here that just took off a GOOD working Carter 2 bbl and is changing over to a 4 bbl. I thought about changing to a 4 bbl,also,. I have 2 625cfm used carbs, but need the intake. My carbs are no telling what condition!!
I still remember the good old days when I could take a core to my good machine shop and have a quality rebuild! Buy a new Edelbrock and BOOM!!

A timing chain is easy to check as well, but I seriously doubt that is what is stalling the engine.
Pull the distributor cap and turn the engine just until the rotor starts turning.
Put a small mark where the timing pointer is on the balancer.
Turn the engine the other way just until the rotor starts to move again and mark the balancer there as well.
How much distance is there between the two marks?
Normal would be about 1/4 inch or so between the two marks.

The clues you gave point to a dirty idle circuit.
Try it, and I'll bet you are surprised.

 

[barbee6043]

A timing chain is easy to check as well, but I seriously doubt that is what is stalling the engine.
Pull the distributor cap and turn the engine just until the rotor starts turning.
Put a small mark where the timing pointer is on the balancer.
Turn the engine the other way just until the rotor starts to move again and mark the balancer there as well.
How much distance is there between the two marks?
Normal would be about 1/4 inch or so between the two marks.

The clues you gave point to a dirty idle circuit.
Try it, and I'll bet you are surprised.

Yes I will try it all again tomorrow!!! No doubt it does not take much to dirty the idle circuit.
You would not believe the tree pollen here the last month!! Spraying yellow primer would not be thicker!!

 

[TrailBeast]

Yes I will try it all again tomorrow!!! No doubt it does not take much to dirty the idle circuit.
You would not believe the tree pollen here the last month!! Spraying yellow primer would not be thicker!!

NASTY.
My Wife would flip out, but I don't have allergies (so far anyway)
It's pollen season here too.

 

[barbee6043]

EGR stuck open?

Put a vacuum gauge on the dipstick tube , flip the PCV out of the grommet and seal both valve covers. If the engine doesn't make pressure almost instantly at 900 rpm, something is wrong. If it pulls a vacuum, the intake gaskets are blown out into the valley, and you should be seeing oil in the tailpipe.

If you have a brake booster, clamp the line and note any rpm change.

Put a timing lite on it and note any timing change going into gear. At 900 rpm the mechanical advance may already have started. Make sure the Vcan is on the spark-port and is not commanding advance at 900 rpm

If nothing turns up, pull the carb off and look for a crack from atmosphere to either port thru the carb platform. I guess check the base gasket is correct for the application, and correctly installed.

If you have a lean burn, make sure the plumbing to it is 100%. If the ECU senses low vacuum it might think the car is working and pull timing. The Vcan should not receive vacuum until the thermo-sensors warm up and relay it. The sensors must be sitting in liquid to properly trigger. On early systems ( I don't know the years), the Ecu was tied to the transmission and no advance was allowed until the trans shifted into hi.
Once all the hoops are jumped thru and the vacuum is "normal", then the Vcan works "normally".
I don't know all the ins and outs of the lean-burn system, as I only ever worked on a few of them. Up here we didn't get LB until the '80s; but this I know; if you pinch the line to the Can, you will not get any advance, lol.

I will also try this today also. The lean burn was long ago gone from PO. I did put a new thick carb base gasket on there too. I did go to parts store for a new PVC but they had to order it and it would have been sent back before I returned to town! lol Thanks for advise to all.

 

[barbee6043]

I pulled the idle screws and cleaned again, it did help idle. I pulled the pretty new looking pvc and blocked that and now I can put it in gear and maintain my idle!! Darn PVC, I cleaned it with carb cleaner other day but did not cure it!
I need to get a teener intake and proceed with one of my used 625's in the parts bin!