Condensor or Coil?

[matthon]

My '58 with a 325 poly has what I would describe as an intermittent misfire or stumble.
Engine runs great otherwise, all cylinders have compression, the lowest at 125.

It's been a while since I've dealt with points ignition.

I was going to buy a new coil, but could it be the condenser, or both?

I'm not sure how to test either, so I put my timing gun on the coil wire, and everytime it stumbled the strobe would follow suit.

Any input/education is appreciated.

 

[pnora]

Condenser can cause that. I fixed one of my Onan generators that would backfire, stumble and miss. On the Onan I can see the points and every time it acted up the points arced oddly. Condenser fixed it. A clear distributor cap would give you a viewing window. I doubt there is such an animal available. Myself I would get a new quality set of points and condenser. Then see what it does.

 

[davek]

Do you have an extra coil to see if that makes a difference? Are you points good?

 

[59pwrwgn]

I haa bad condenser. Sometime it would run fine other time not. Remove it and see if that clear up your problem

 

[turbine68rt]

Check your dwell on a meter to see if your rubbing block is excessively worn, giving too much dwell. The more dwell you have the more the timing will retard, (assuming that hasn't been adjusted since the points were last installed). If you install/gap a new set of points, be sure to check/adjust the timing after your dwell is set.

 

[matthon]

Do you have an extra coil to see if that makes a difference? Are you points good?

I do not have an extra coil. I only have multiple MSD coils for electronic ignition.

I haa bad condenser. Sometime it would run fine other time not. Remove it and see if that clear up your problem

Remove it completely?

Check your dwell on a meter to see if your rubbing block is excessively worn, giving too much dwell. The more dwell you have the more the timing will retard, (assuming that hasn't been adjusted since the points were last installed). If you install/gap a new set of points, be sure to check/adjust the timing after your dwell is set.

Is there a specific meter to check dwell? I'll have to search on how to do it.
The points, cap/rotor, plugs, wires, were all replaced 30 years ago when it was parked, I don't even think it was started with the new parts.
I installed a rebuilt carb, replaced the negative coil wire, primed the engine, set the timing, and it fired right up.
Ran great for a while, but now has a stumble.

 

[matthon]

Short clip of it when it first ran, it is running fine.
I took a longer video where you can hear it stumble, if you listen closely, but have not uploaded to youtube.

 

[pnora]

Short clip of it when it first ran, it is running fine.
I took a longer video where you can hear it stumble, if you listen closely, but have not uploaded to youtube.

I did not hear a stumble. I even closed my eyes for a better listen.

 

[Lefty71]

If you pull the coil and it's sloshing, like not full of oil, then I'd say it's your best bet.... Otherwise, it really could be either, as others have alluded to.

 

[toolmanmike]

My '58 with a 325 poly has what I would describe as an intermittent misfire or stumble.
Engine runs great otherwise, all cylinders have compression, the lowest at 125.

It's been a while since I've dealt with points ignition.

I was going to buy a new coil, but could it be the condenser, or both?

I'm not sure how to test either, so I put my timing gun on the coil wire, and everytime it stumbled the strobe would follow suit.

Any input/education is appreciated.

I would contact @HALIFAXHOPS for a quality condenser. The ones sold at parts stores nowdays are junk.

 

[69 Sleeper Bee]

Sounds like she fixed herself to me


Load up the longer video of the stumble

 

[wagonman]

What you need or put the wire off condenser on a plug wire to charge it. Throw it to somebody you don't like, If it knocks them on their *** the condenser is probably good.

 

[Geoff 2]

Engine will not run without the condenser. Check/set points gap at about 0.016", not critical.
If it still misfires, it can be anything in the ign cct: ign sw, wiring, connectors etc. Process of elimination.

 

[matthon]

I shot a video today of the stumble, but I can't even hear it in that video.

The link below is multiple videos made over months put together.
I hear it at around the 48 min mark, and it seems to go away once I drive it, as well as at the hour mark.

It appears it has come and gone and I never really noticed it, as it was not all the time, until someone pointed it out.
It does seem to be more constant now, or I'm tuned into it.

 

[toolmanmike]

Sorry to say but it sounds like it's running on about 4 cylinders. It must be idling at 300 rpm or so.

 

[turbine68rt]

Is there a specific meter to check dwell? I'll have to search on how to do it.

Yes, a dwell meter.
@HALIFAXHOPS can set you up with that.

 

[HALIFAXHOPS]

I have tons of them calibrated, really what do you want it all to do except dwell? Need other tune up tools also? Have a few kits also.

 

[59pwrwgn]

I was on a road trip. The engine stated running rough and finally died and and wouldn't restart. When I removed the condenser it started and ran fine. Dont recall if I had another to replace it, drove it 3 hours to my destination and 6 back.

 

[matthon]

So I'll go through what I checked later.

First pic is distributor in the 325.
The important question is should the points just be hanging out on the opposite side of where the condenser screws on with the coil wire?
My guess is no.

So I looked at a distributor I have off a 383, which has a plastic piece and the points screwed to the opposite side.

I'm going to switch the 325 points to the other side where they can be screwed down.

It appears the purpose of the plastic piece is to isolate the points from the distributor., but I can't swap in the other points.
When I look online for new points, nothing in stock anywhere, there is no plastic isolator, in the pics at least.

I looked for points for my 64 Fury and it shows one with the plastic piece, one without.
Seriously, they don't even give you it, I'd have to reuse the one I don't have?

I did not install the points, but I definitely should have caught this sooner.

 

[toolmanmike]

I was on a road trip. The engine stated running rough and finally died and and wouldn't restart. When I removed the condenser it started and ran fine. Dont recall if I had another to replace it, drove it 3 hours to my destination and 6 back.

6 volt system?