Misfiring while cruising

[wil84911]

Started last night. Split second misfiring while cruising. This happened weeks ago and gas treatment eliminated it it seems. Could you point me where to start looking? I seem to be getting old for this . Thanks
 

 
12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

[siteunseen]

How old is the distributor cap and rotor button?  Could be jumping fire.

Do you have the OE points distributor, if so the points may need adjusting or replacing.  Maybe just a good tune up would fix your problem.  Good luck. 

Edited May 22, 2018 by siteunseen

[wil84911]

How old is the distributor cap and rotor button?  Could be jumping fire.
Do you have the OE points distributor, if so the points may need adjusting or replacing.  Maybe just a good tune up would fix your problem.  Good luck. [emoji4]

Exactly my thoughts. Prob due for tuneup. Car came with Mallory. Thanks



12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

[Patcon]

5 hours ago, wil84911 said:

Exactly my thoughts. Prob due for tuneup. Car came with Mallory. Thanks

Overall that doesn't look like the issue...

[Zed Head]

13 hours ago, wil84911 said:

Started last night. Split second misfiring while cruising. This happened weeks ago and gas treatment eliminated it it seems. 

Some thoughts that popped in to my head while reading the thread.  Before I went to bed.  I'm glad your car's not red.

What do you mean by "cruising"?  And is the problem really gone now, after just pouring some stuff in the gas tank?

Edit - more correctly - did the problem really disappear weeks ago, and it has come back?

Edited May 23, 2018 by Zed Head

[wil84911]

Some thoughts that popped in to my head while reading the thread.  Before I went to bed.  I'm glad your car's not red.
What do you mean by "cruising"?  And is the problem really gone now, after just pouring some stuff in the gas tank?
Edit - more correctly - did the problem really disappear weeks ago, and it has come back?

Started hapenning at steady highway speed. Yes gas additive cured it weeks ago. Seems worse this time.


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

[Zed Head]

A tuneup can't hurt.  Sometimes minor issues become more noticeable at steady engine speeds.  Seems like a fuel issue would get worse after it started.  I know that in the old days we would adjust our plug wires to avoid crossfire caused missing.  Your distributor cap looks very clean on the inside, to Patcon's comment, but you can get shorts on the outside also, from dirt and grime.  New plugs, wires, cap and rotor might do it.  Good luck.

[Mark Maras]

  A little more info would help. Is the problem ongoing? I'd start with a complete tune-up. Did you fill your tank at the same gas station after the previous successful fuel treatment. They could have water in the bottom of their tanks. My Dad would never stop at a gas station that had a tanker sitting in the lot. He said filling the underground tanks would stir up the water sitting in the bottom of the tanks and allow it to be pumped into a vehicles tank.

[wil84911]

Thanks Mark. No seems problem is occassional misfire that got worse. But anyway its all coming back to me. Sanded the distributor cap and rotor points then drove it like a thief.. voila problem gone. Looking to complete the tuneup before the planned rebuild woohoo. Should I stay with this mallory setup?


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

[wil84911]

Help please! This oldy cannot figure out which Mallory cap and points he needs. I don’t see any part number that matches ones on Mallory site. Thanks



12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

[Mike W]

I used to run the Mallory Unilite but switched to the 123 Ignition setup.  A couple of comments about the Unilite / Mallory from my experience:

1. Mallory was acquired by MSD a while back and as a result the Unilite made for the L6 engine is NLA.

2. On my original Mallory setup the part number for the distributor cap was 270 and the rotor was 339.  You should be able to still get these through MSD or even Amazon.

3. The electronic module in the Unilite distributor was known for being susceptible to spikes on the 12V line and could go bad as a result.  Due to that I always carried a spare with me (never had to use it) and also installed a Mallory power line filter to eliminate any 12V spikes. 

Hope that helps and good luck with solving your problem.

Mike.

[Captain Obvious]

Replacing the cap and rotor (or any other tune-up style work) with new certainly can't hurt, but I worry your sanding of the electrodes and having the problem go away is a red herring.

How do you know it was misfiring? What I consider a misfire is usually harder to detect at higher RPM's.  Did it cut out completely for a short period of time while you were on the highway? Or did it feel like it was just running unevenly and "pulsing"? "Judder-ing" (Is that even a word?)