51 mercury miss while running at 50 to 55 mph

[Brooklynn1]

I have been fighting this miss for awhile, the car runs fine, starts great and has good power when I floor it, runs right up to 70 mph. But running at a steady mph or rpm it has a miss. Carb is stock 885ffg rebuilt, I installed protronic electronic ignition with coil, new plugs cap roter, timing seams to be on. Any thing I missed. Really getting frustrated. Thanks for reading, anybody have any ideas?

[BUBBAS IGNITION]

I am assuming you mean "pertronixs". I would check the coil when this happens , pull over and touch the coil housing, if its way too hot you have a defective coil. Check the resistance with a ohm meter from positive to negative should be a min 1.5 ohms ...

[51 MERC-CT]

Also I believe Pertronix recommends use of 'spiro-wound' (carbon core) plug wires to help prevent mis-fire due to plug wire emissions.

[40cpe]

Originally Posted by BUBBAS IGNITION

I am assuming you mean "pertronixs". I would check the coil when this happens , pull over and touch the coil housing, if its way too hot you have a defective coil. Check the resistance with a ohm meter from positive to negative should be a min 1.5 ohms ...

Bubba, you da man!! I have a y-block with a <2000 mile pertronix and Blaster coil. I have had an intermittent skip with it and was about to go back to points to see if it was the ignition. I did notice a few days ago that the coil was hot, but thought "It's new". I ohmed the coil at 1.9 so I thought it was OK. Today I installed the Bosch Blue coil that YOU put us on to at a bargain. I just came back from a 15 mile test and NOT A SKIP. Thank you for sharing your experience and knowledge with us.

[19Fordy]

Perhaps the Pertronix module is heating up and then dying after about 20 miles when car was warmed up.
Had that happen to a Mallory Uni-Lite.

[40cpe]

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We'll see how it does. Ambient temps were 90 at the time and I was running the AC. Oddly enough, previously it would skip more before the car was fully warmed up and almost go away at normal running temp. If anything changes I will update.

Correction to the above post: It was a Flame Thrower coil from Pertronix that i removed, not a Blaster.

[50fordcoupeman]

I also had the same symptoms with a pertronix set up. Car ran great until it got warmed up and run at a steady speed-then I wondered if I would make it back home. The problem turned out to be the coil. Three years running without a problem. Good luck!

[Mike51Merc]

Although I agree that ignition might be a problem, but you might also look into your valve train to see if you have a sticky valve or two.

[40cpe]

I'm bringing back this older thread to report on the "skip" that I thought was gone and to ask a question. I was running a pertronix Ignitor with their Flame Thrower coil. Bubba said some of the coils might have problems running hot (paraphrased) so I changed mine. The skip went away temporarily but came back. I emailed Pertronix tech line with my symptoms. They had me check the ground resistance (which was good) and for the magnet ring to be equal height with the Ignitor. The ring was .030" lower than the ignitor. They suggested putting an o ring under the magnet ring. I did, and just came back from a test drive. Again, no skip, and I THINK it runs smoother. So I'm cautiously optimistic but I'll post again if it doesn't work.

I checked the temp of my coil when I got back from the drive and it was 135 degrees, hot to the touch. Is that too much, or about normal?

[tubman]

Every time I read one of these posts I have to wonder why people install these things. To repeat an oft-told story : I bought my '51 Ford in 1987. At that time, I did a tune-up replacing the cap, rotor, points, plugs and condenser. I pulled the engine in 2016 because it was getting a little weak and making a funny noise. After 29 years and 17,000 miles (during which the engine ran smoothly, despite slowly loosing power), an inspection of the plugs and points showed little wear and units probably good for another 10 years and 10,000 miles.

[34PKUP]

Originally Posted by 40cpe

I checked the temp of my coil when I got back from the drive and it was 135 degrees, hot to the touch. Is that too much, or about normal?

Suspect that just about everything under the hood will be close to 135°

[Marv]

Originally Posted by Brooklynn1

I have been fighting this miss for awhile, the car runs fine, starts great and has good power when I floor it, runs right up to 70 mph. But running at a steady mph or rpm it has a miss. Carb is stock 885ffg rebuilt, I installed protronic electronic ignition with coil, new plugs cap roter, timing seams to be on. Any thing I missed. Really getting frustrated. Thanks for reading, anybody have any ideas?

A vacuum leak can cause this.

[51 MERC-CT]

Originally Posted by 40cpe

I'm bringing back this older thread to report on the "skip" that I thought was gone and to ask a question. I was running a pertronix Ignitor with their Flame Thrower coil. Bubba said some of the coils might have problems running hot (paraphrased) so I changed mine. The skip went away temporarily but came back. I emailed Pertronix tech line with my symptoms. They had me check the ground resistance (which was good) and for the magnet ring to be equal height with the Ignitor. The ring was .030" lower than the ignitor. They suggested putting an o ring under the magnet ring. I did, and just came back from a test drive. Again, no skip, and I THINK it runs smoother. So I'm cautiously optimistic but I'll post again if it doesn't work.

I checked the temp of my coil when I got back from the drive and it was 135 degrees, hot to the touch. Is that too much, or about normal?

Just to clarify, is this what you are talking about?

[richard crow]

i don,t know why you guys put them on your cars the stock ign works fine much ezer to repair the points will last 10,00 miles & if you have trouble a match book & a screw driver will get you home.

[40cpe]

Originally Posted by 51 MERC-CT

Just to clarify, is this what you are talking about?

That is correct, Pertronix said they should be even. Mine was .030" low on the magnet ring. I wouldn't think it would make a difference, but apparently so.

Originally Posted by richard crow

i don,t know why you guys put them on your cars the stock ign works fine much ezer to repair the points will last 10,00 miles & if you have trouble a match book & a screw driver will get you home.

Unless your condenser craps out, which mine did. Then you have to go in your distributor. IF your Pertronix fails, a screwdriver and matchbook installs your points and condenser that you keep in the trunk.

[40cpe]

Originally Posted by 34PKUP

Suspect that just about everything under the hood will be close to 135°

Good point!

[51 MERC-CT]

Originally Posted by 40cpe

That is correct, Pertronix said they should be even. Mine was .030" low on the magnet ring. I wouldn't think it would make a difference, but apparently so.



Unless your condenser craps out, which mine did. Then you have to go in your distributor. IF your Pertronix fails, a screwdriver and matchbook installs your points and condenser that you keep in the trunk.

Yep, I suppose instead of an 'O' ring to correct, a suitable thickness flat washer could be used.
I don't carry a spare unit but do carry a complete distributor.
Had a Unilite unit quit some time ago and replaced it with a Pertronix equipped distributor, right in the Cruise nite parking lot. (would rather do that than fiddle with little screws or stringing wires etc. )

[tubman]

All of my cars have points ignition systems and I have never even considered the advisability of carrying a spare distributor (or any electrical components).

[34PKUP]

Originally Posted by tubman

All of my cars have points ignition systems and I have never even considered the advisability of carrying a spare distributor (or any electrical components).

Isn't it great how each of us has the ability to choose what is suitable for themselves.
I'm sure that there isn't anyone who is advising or forcing you to carry spare parts and that's your choice.

[36rgtop]

Originally Posted by tubman

All of my cars have points ignition systems and I have never even considered the advisability of carrying a spare distributor (or any electrical components).

Guess you have never considered buying a 'new' car either