318 stalls on idle

[soundcontrol]

I tested my 70 Barracuda (318 with a 2-barrel) on the road for the first time. Engine runs fine, but stalls on idle if I first rev it, or drive it normally and brake. It can run on idle a long time if it just sits and I don't rev it. I tried different timing settings. Plugs, breaker points, rotor, dist cap are new. I tried a different carb that I borrowed from a friend, I was pretty sure it was a carb problem, but it behaves similar with both carbs.

If I rev it and then lightly tap on the pedal just to get the acc pump going a slight bit, it does not stall. I tested for vacuum leaks around the carb, sprayed carb cleaner around it, first time I got an increase in rpm's when I sprayed around the carb foot on the left side, but I sealed the gasket (a very thick one) on both side after cleaning it, seems good now. Still stalls though. Could the hose to the AC control (thats hooked up to the intake) cause that? Ac don't work and I did not check the other end of that hose yet.
I also changed the pcv valve to a new one.

Pict at 11:30 PM, no dark nights in Sweden at this time.

[Bullitt-]

My initial thought is vacuum leak or carb is way out of adjustment...
   Check with a Vacuum Gauge
https://www.onallcylinders.com/wp-content/uploads/2016/03/31/vacumm-reading-1.png

[Chryco Psycho]

It has to be going too lean when you snap the throttle closed which is why touching the throttle as it drops keeps it running , my first thought is the float level is too low & starving the idle circuit , the air bleeds could be problematic also , make sure they are clean .
If it is vacuum related try plugging the hose to the brake booster , you can have a vacuum leak inside the booster .

[dodj]

It has to be going too lean

Yup.
Richen your idle and see if it stalls.

[worthywads]

Where is your idle timing at?  Vacuum advance working?

[jringo8769]

Well I would check the carb a cracked accelerator pump on it would do this too
I would also do a compression check as a valve issue could do this too
Ran into this year's ago with a truth I bought that run oddly
Stay safe out there
God Bless,John
Vacuum gauge is also a great idea to see how well it is running too


Sent from my SM-S727VL using Tapatalk

[soundcontrol]

Thanks guys. I did a compression check, fine on all cylinders. Manual brakes no booster. Did try to richen the idle. My timing seems to be high, I can't see the mark because the waterpump blocks the view if it is over 10 degrees. If I lower it it will stall right away. I usually set the timing roughly in the area when the engine RPM changes and then check with a light.  If I put it there (where it runs good) it seems to be over 10 degrees. Maybe the mark on the balancer is out...

I will get a vacuum gage and check that. Unless the 2 carbs has exactly the same issue, I'm leaning towards a vacuum issue now.

[soundcontrol]

Looks like it still leaks at the foot. even though I sealed it twice with different sealers. The original gasket is more than 1/4" think and has metal sleeves in the bolt holes, might not be enough with a sealer.

[70 Challenger Lover]

Thanks guys. I did a compression check, fine on all cylinders. Manual brakes no booster. Did try to richen the idle. My timing seems to be high, I can't see the mark because the waterpump blocks the view if it is over 10 degrees. If I lower it it will stall right away. I usually set the timing roughly in the area when the engine RPM changes and then check with a light.  If I put it there (where it runs good) it seems to be over 10 degrees. Maybe the mark on the balancer is out...

I will get a vacuum gage and check that. Unless the 2 carbs has exactly the same issue, I'm leaning towards a vacuum issue now.

I have a 318 2 barrel and I run my initial timing much higher with great results. If I remember right, I think I'm around 22 degrees with the vacuum advance connected. Idles nice. Responsive. Decent mileage. No pinging of course with such low compression. I don't know that this helps your stalling issue but I thought I'd mention it for other reasons.

The thing that puzzles me is you have tried two different carbs so strange that both would have a defect. Particularly when it probably was fine on the other car. Maybe your engine just needs a richer shot of fuel though?

[soundcontrol]

Thanks guys. I did a compression check, fine on all cylinders. Manual brakes no booster. Did try to richen the idle. My timing seems to be high, I can't see the mark because the waterpump blocks the view if it is over 10 degrees. If I lower it it will stall right away. I usually set the timing roughly in the area when the engine RPM changes and then check with a light.  If I put it there (where it runs good) it seems to be over 10 degrees. Maybe the mark on the balancer is out...

I will get a vacuum gage and check that. Unless the 2 carbs has exactly the same issue, I'm leaning towards a vacuum issue now.

I have a 318 2 barrel and I run my initial timing much higher with great results. If I remember right, I think I'm around 22 degrees with the vacuum advance connected. Idles nice. Responsive. Decent mileage. No pinging of course with such low compression. I don't know that this helps your stalling issue but I thought I'd mention it for other reasons.

The thing that puzzles me is you have tried two different carbs so strange that both would have a defect. Particularly when it probably was fine on the other car. Maybe your engine just needs a richer shot of fuel though?

That sounds about right with the timing, if I put my light on Cyl 8, I see the line, and by kinda dividing the balancer up in 4 parts and estimating where it ends up, the line would be about 20 degrees, even if I can't see it.

[YellowThumper]

I also surmise it is vacuum leak related.
With a vacuum leak your engine idle speed will increase. Combating this increase will be adding more jetting and dropping of idle. This masks the leak and then you end up with a weak idle that wants to die. Because... all other adjustments are set for it to die compensating for the leak.
Been there...

My old school lesson for initial timing is to adjust until there is a miss. Then back off.  Not saying it is correct but will provide a possible improvement. If motor has been rebuilt prior. There is also possibility cam may not be installed neutral.
Vacuum guage tells all.

[Bullitt-]

sounds like you could use tape for your damper  https://www.summitracing.com/parts/dcc-p4529070ab

Or measure 1" from TDC & paint a mark for 16-degrees then 2-3/8 for 36-degrees


Also I've been fooled by the spray test... the aerosol will get sucked into the leak but not necessarily from where you are directing it..   

[soundcontrol]

I took the carb out for the third time and made a new rubber gasket, the old one broke in 2 parts this time when I removed it, but now it seems to idle better, and it does not rev up if I spray the foot, can't really test to rev it etc, because its close to midnight here and my neighbours are sleeping 

Will test run it more tomorrow.

[71383bee]

sounds like you could use tape for your damper  https://www.summitracing.com/parts/dcc-p4529070ab

Or measure 1" from TDC & paint a mark for 16-degrees then 2-3/8 for 36-degrees


Also I've been fooled by the spray test... the aerosol will get sucked into the leak but not necessarily from where you are directing it..   

Sounds like you don't have a timing light that can advance.  They are worth every penny for these cars! 

I had a 72 2 bbl 318 satellite that responded as good as any of the hi po motors by advancing it.  Its tough to set total without a dial advance light but i would set total at 34 and see where initial is at. That alone should be an improvement.  I'm sure there are other tricks that can get you close with your ears and a vacum gauge. 

Might be worth rebuilding the 2bbl.  They are super easy to rebuild and the FSM has a bunch of info on how to set it up right.  Since you got 2 you have a great candidate.  It wont pull stumps but they are very reliable carbs/motors.  I loved

[soundcontrol]

Seems to run fine now with a home made rubber gasket.
Nope, my timing light is a standard one. I set the timing as high as I could now, the distributor cant go any further without reclocking it now.
Gonna paint some marks and check where I'm at with the timing.
I think an electronic ignition would be a big improvement, and the distributor axle has some play in it, not great for the breaker points....