Hey guys. A couple new issues have arisen unfortunately.

When I pull up to a stop light, the idle gets a little rough, and then when I go to move forward again, it wants to stall and I have to pivot the accelerator back and forth rapidly to keep it going. In park and neutral it idles great. It drives well too. Could this be due to a potential vac leak somewhere? What should I investigate to try to solve this issue as its a pain in the ****? Could this be because I have the two idle speed screws mucked up? I have never found a good tutorial on how to set those.

I have also noticed a small engine tick that has developed recently. No work has been performed on the block for a couple of years. How concerned should I be? I'm looking to put 4,000 miles on her in about 3 weeks so I want to be confident.

Here is some potentially helpful info. Stock motor, rebuilt stock holley 2 bbl carb, mix screws tuned at idle for max vacuum. Re-did all gaskets on intake manifold and valve covers 2 years ago. All new vac lines. Engine was timed to stock configuration 2 years ago. New dizzy cap, rotor, plug lines, and spark plugs (gapped to stock recommendations). New air filter, recent oil change and new oil filter. New fuel pump and fuel filter 2 years ago. I'm running about 14 inches idle vacuum and compression in all cylinders is with in an acceptable range.

All help is greatly appreciated. Let me know if there is any more info I can give out

 

I would go back and check the carb base gasket for vacuum leaks Re check the vacuum lines, small tick ? maybe check plug wires for arcing (in the dark ) check the brake booster for vacuum leaks too !

 

Brake system was just inspected 2 days ago as I had the master cylinder replaced. The base gasket on the carb is clean with no leaks.

I'll check the plug wires

 

Sounds like a bad plug wire for the ticking.... If you get that fixed it will more than likely take care of the stumble.... but if not...

Check the Carburetor accelerator pump for a good strong discharge.

Do you have a carb that looks like this one?

 

Very close, but there is only one vacuum powered choke which I just replaced. Accelerator gives a good discharge into both jets.

I'll throw new plug wires on it tomorrow and see how that works.

 

If it's got Champion spark plugs in it...Get rid of those too... Put NGK's or Autolite's in it....

 

It sounds like a vacuum leak for the stalling check all the lines and get a new PCV valve.. One of the easiest ways to check wires is to spray water on them from a squirt bottle if they arch then they're bad. I dont agree keep the champions they are the perfered plug for mopars.Plug # (RN12YC) Good luck and have a nice trip...Bill

 

The pcv valve was taken out and cleaned pretty thoroughly last year. Just has the one moving little part in it afterall.

I'm going to disconnect and plug the vacuum line that runs to the cruise control as that never worked nor do I care haha. I really appreciate the help guys.

 

I've seen Pcv valve that were not the right ones cause the same problem that you are experiencing.. They are calibrated to the engine I would if it were me get one from the dealer. Just my $.02...Bill

 

The pcv valve should be stock. Never replaced it and I doubt the old lady I bought the RV from would have replaced it either. As I said, took it out a few years back, gave it a good clean. Engine has only driven maybe 8,000km since. But I'll pull it today and inspect it.

Plug wires are now on. Seems to run better, still feels kinda weak while idling under load. lets say I do find a vac leak that is not due to cracked or improperly fitted lines. is there any type of sealer I could use around a gasket? I'd rather not pull everything apart again to re do gaskets.

Also, I bought an aftermarket tac a couple of years ago but it seems to give really high readings. The engine should idle comfortably around 800 rpm, but tis giving me readings of 2,000 rpm....

 

http://www.lucasoil.com/products/dis...catid=2&iid=26

Use some Lucus fuel treatment.... Help with todays fuels... Might have some weak fuel in the tank?

Make sure Your tach is set to the 8 cylinder setting...

 

Goood news everyone. The new plug wires seemed to have helped a lot! I guess fiddling with the old ones i bought a few years ago may have wrecked a couple. I also disconnected the vac line to the cruise control and plugged the port which also seems to have helped a bit. SHould I re-time the engine now incase there was a small vac leak in that system?

 

If you had disconnected the vacuum advance like you should ? when you set the timing It will be fine. I would still run some fuel system cleaner through it I would also run it with some fuel stabilizer also when it is parked

 

thx

 

Hi Guys,

I have a 78 D200, very original old girl, I'm having similar issues with the brake booster. Basically I'm doing all the work with the brakes and whenever I apply the brakes she threatens to stall. I assume I have a leaking booster, would that be right? could it be a hose? any tips of I.D.ing the problem?

Cheers Gents

 

There is a check valve in the booster circuit where it connects to the booster

 

Plug the hose and see if the problem dose away... If it dose, it's the booster thats defective....