What is causing my misfiring while driving ?

[khryslerkid]

Evan if you have some dirt in the fuel filter I'd check in the carb again for any.

I had a set of MSD wires and the first problem I had was they wouldn't stay on the plugs. The clip inside the boot is made of a steel that doesn't have any memory. They open up when pushing onto the plug and stay open, making them loose. The boot would hold onto the plug but when they got hot they would back off. Just that little bit of distance not making a connection would make the cylinder pop. Damn things were coming disconnected during my cam break in. Replaced them with Firecore wires and haven't looked back.

Get yourself a dwell meter for a more accurate setting of the points. Good luck finding the problem. Think simple first.

 

[Ski 61701]

Evan this is probably going to be an easy....but time consuming fix. Sure it will test your patience.. but once you figure it out.. please let us know.. Lots of great suggestions from people here.

 

[Billccm]

I too had the same issue as khryslerkid with MSD wires. I went with firecore also, and if I had to do over again I would go Taylor wires.
Having said that I'm not so sure wires are your issue.
I wonder if you could swap the distributor with a ready to run electronic? That would eliminate a big part of the possible causes.

 

[Evan Frucht]

Well after two days of doing nothing, the car now wont even really start. It will crank and fire but is really rough. Stomping on the gas will sort of keep it going. Would a video or something possibly help?

One thing I just noticed is the rubber hose that goes from the right side valve cover to port on front of carb... has a big crack in it ?

 

[Billccm]

Vacuum leak would cause this issue

 

[Glenwood]

try smothering the carb to check for vacuum leaks
it might be worth using an IR gun on each exhaust port to see if all cylinders are firing in case you have some valve issues.

 

[Evan Frucht]

Vacuum leak would cause this issue

Would the cracked breather hose going into the carb cause a vaccum leak?

 

[Evan Frucht]

Alright that's it! Carb is coming off. Time to fix this.

Hopefully the carb is just clogged. When I pulled out the fuel hose a bunch of gas poured out of the carb bung ( not the hose) that made me think it was overfilling inside with no where to go... a clog maybe.

Also btw a cracked breather hose makes no difference.... I plug it and it's still the same....

 

[Don Frelier]

Sounds like a PCV valve line and yes that should make a difference.

 

[Evan Frucht]

Ok so after cleaning the carb I got the car to start back up and stay idling sort of but something is still definitely off.

Out of curiosity I simply disconnected the vaccum line going from carb to vaccum canister on distributor. When I rev it both connected and disconnected it seems that there is no change.

I'm wondering if my vaccum advance canister on the distributor has possibly failed. The can and distributor definately look old.

 

[Don Frelier]

You can put your mouth on that line connected to the advance and see if you can sense the diaphragm move and even watch inside the distributor. If it leaks you should be able to tell as well.
They can get physically stuck inside there is a plate that rotates the points assembly forward.

 

[Evan Frucht]

Ok so both sucking and blowing through that vaccum line attached to distributor I see no movement inside the distributor. I can also hear a hissing of air.

So your saying the canister could be fine but the mechanism might be stuck

OR

That the vaccum canister could be toast

 

[Evan Frucht]

I can move the top plate in the distributor by hand (but it takes a decent amount of force )

That leads me to believe it is not stuck. But I'm not sure how easy they are supposed to be to turn, or how much there are supposed to turn. It turns about a centimeter counterclockwise and it is hard to turn. I can barely rotate it with my bare hand but if I push on it with a screwdriver it turns.

 

[Evan Frucht]

I also wondering how likely a vaccum canister issue is to cause my syptoms. I read on here some people just disconnect it and run it only mechanically and the car runs fine.

This all started as some intermittent misfiring while driving around with roughly half throttle.

The barely being able to start and keep running is the most recent addition to the issue.... possibly caused by efforts to fix it?

But this issue is really about it missing and stumbling at medium throttle. Feels like it starts to happend when it's under load accelerating for the most part. Maybe 2000-2500 or so rpms.

BTW. I though it was original but looking at ot closer this distibutor on the car seems to be one of those cheap $50 aftermarket replacements. I have no idea if those are know to fail or cause problems... but my car has been running fine for the last year or so. I even recently drove it on a trip from Los Angeles to Big Sur. About a 5 hour drive up the coast. It didnt skip a beat the whole time and ran great directly after the trip. The car was also fully loaded with 5 people and luggage...

So this was a good running car... but then these symptoms came out of nowhere.

 

[turbine68rt]

Ok so both sucking and blowing through that vaccum line attached to distributor I see no movement inside the distributor. I can also hear a hissing of air.

So your saying the canister could be fine but the mechanism might be stuck

OR

That the vaccum canister could be toast

Right after completing the break-in process on my 440 I was making final timing adjustments and noticed there was no change when connecting or disconnecting the hose. Took the canister off, did an autopsy and my hunch was correct. A dry rotted, split diaphragm. Installed another one that tested good and runs perfect ever since.

 

[Evan Frucht]

The thing that is also worrying me is how hard it is to manually turn the top plate inside the distributor... I dont know what is normal.

I wondering if I messed something up when I installed the new points and condenser.

 

[Glenwood]

I ran my poly without the vac advance connected as it would not run properly otherwise. It ran ok but consumed lots of fuel. I planned on a bb swap so I didn't care.
The plate should move without too much trouble since there are only 2 light springs providing tension. I would tear it down, clean and lube it all up. Your problem may very well be carb or fuel delivery related though. Like it's running out of fuel.

 

[Evan Frucht]

I ran my poly without the vac advance connected as it would not run properly otherwise. It ran ok but consumed lots of fuel. I planned on a bb swap so I didn't care.
The plate should move without too much trouble since there are only 2 light springs providing tension. I would tear it down, clean and lube it all up. Your problem may very well be carb or fuel delivery related though. Like it's running out of fuel.

Ya I am not ruling out fuel problems. But...

My fuel pump is pumping. (I found that out by forgetting to reconnect the fuel hose after reinstalling carb and cranking)

The carb had some very fine debri settled in the bottom of the bowls which I cleaned out. I cleaned out all the passages with solvent and compressed air and carb cleaner. I am pretty confident it is working properly and not clogged. I re-installed it and dressed the gasket with loctite 518 anaerobic gasket sealer which Is a very good and proper product for this. I do NOT think I had a vaccum leak before, and I definitely don't now.

The only other thing could be the fuel pickup in the gas tank... but this is a wagon and it's harder to get to and remove (I think.) So I do want to rule out all other possibilities first.

What else could I be missing. Valves probably need an adjustment but this problem started one second to the next.

I'm no so concerned with getting the car running in perfect tune. I can take care of that when I have more time... but I would like to be able to drive it and not worry about it completely dying on me or not starting randomly. This problem started out a few weeks ago while I was on freeway. one second to the next, it just started missing, then it would go back to normal for a few miles, then it would act up again. It seemed to be getting more frequent the last few time I drove it. Then this morning it would barely start and ran really rough... I didnt even try to test drive it...

 

[khryslerkid]

The thing that is also worrying me is how hard it is to manually turn the top plate inside the distributor... I dont know what is normal.

I wondering if I messed something up when I installed the new points and condenser.

It takes a screwdriver in the points table to move it. I don't think you'll do it by hand or using your fingers.

You said you heard air escaping when you draw vacuum on the can. That very well would be a bad diaphragm in the can. (That probably isn't you problem) What timing are you running? Hook your timing light up and watch what it does when you rev it up. It will advance a little by the springs under the table. Watching what the timing mark does can show you what else is going on like a sloppy timing chain.

Make sure the wire to your points isn't touching the distributor on the inside shorting the points. Make sure the insulator where the wire fastens to the points is in good shape and not creating a short along with the condenser wire.

Pull a plug wire and hook it up to a spare plug, ground the plug and see how the spark looks when cranking.

What carb are you using? Does it have a good squirt, looking into the carb when pulling back on the throttle

Like I said before think simple little things first.

 

[Evan Frucht]

It takes a screwdriver in the points table to move it. I don't think you'll do it by hand or using your fingers.

You said you heard air escaping when you draw vacuum on the can. That very well would be a bad diaphragm in the can. (That probably isn't you problem) What timing are you running? Hook your timing light up and watch what it does when you rev it up. It will advance a little by the springs under the table. Watching what the timing mark does can show you what else is going on like a sloppy timing chain.

Make sure the wire to your points isn't touching the distributor on the inside shorting the points. Make sure the insulator where the wire fastens to the points is in good shape and not creating a short along with the condenser wire.

Pull a plug wire and hook it up to a spare plug, ground the plug and see how the spark looks when cranking.

What carb are you using? Does it have a good squirt, looking into the carb when pulling back on the throttle

Like I said before think simple little things first.

Thanks!

Yes I can hear air escaping when I suck or blow on the vaccum line. I thought my canister might be bad but I think you are right... that isnt my main problem here anyway ( it could have gone bad a long time ago for all I know.) I need to narrow things down here.

The accelerator pump has a good strong squirt. That was one of the first things I checked. It's a Carter AFB.

I will do what you said and report back.