The Ford Barn

AstroZombie · 08-03-2011, 04:24 PM

Just as the title says, I am experiencing a miss at cruising speed. Not anything I can really feel, but I can hear it. Car starts and idles perfectly, no other issues whatsoever. I have tried messing with the GAV, but there's no change. It has been getting worse the past few months then my el cheapo condenser died on me. I replaced it with a Henry condenser, regapped the points, and plugs last week. (hoping I would fix the miss also) It is running smoother than ever, but I still have that miss. It's frustrating, and annoying. Would anyone have an idea where to start searching?

All ignition wiring is good
Cleaned the carburetor out as well
Plugs gapped at .030
Points gapped at .018

I'm clueless....

Gary WA · 08-03-2011, 05:22 PM

Try 35 on plugs. and check gap on cap to rotor all four.20-30. may have a crack in cap.

John S · 08-03-2011, 05:41 PM

Check the point gap on each cam lobe. It is possible for the distributor cam to be worn enough on one lobe to cause a miss.

Patrick L. · 08-03-2011, 05:43 PM

Have you checked coil polarity ?? Improper polarity can reduce secondary voltage by 15-30% causing a high speed mis-fire..
Check this;http://www.chicagolandmgclub.com/tec...neral/574.html

AstroZombie · 08-03-2011, 05:56 PM

Quote:

Originally Posted by Gary WA

Try 35 on plugs. and check gap on cap to rotor all four.20-30. may have a crack in cap.

I will try the .035 on the plugs. Never thought about the rotor to cap gap. That may be a good start. My cap is old and crappy looking, I was planning on replacing it anyway.

Quote:

Originally Posted by John S

Check the point gap on each cam lobe. It is possible for the distributor cam to be worn enough on one lobe to cause a miss.

That could be a very good possibility. When I regapped the points they were WAYYYY off. The wear block on the point is badly worn. I planned on replacing points, when I replaced the cap. (see above)

Quote:

Originally Posted by Patrick L.

Have you checked coil polarity ?? Improper polarity can reduce secondary voltage by 15-30% causing a high speed mis-fire..
Check this;http://www.chicagolandmgclub.com/tec...neral/574.html

Thanks, I have not checked the coil. It is old and crusty, but never gave it a consideration.

Thanks all who replied. A "miss" is difficult to troubleshoot since there are so many variables. I appreciate the insight.

700rpm · 08-03-2011, 06:03 PM

Sponsored Links (Register now to hide all advertisements)

"My cap is old and crappy looking, I was planning on replacing it anyway."
"The wear block on the point is badly worn. I planned on replacing points..."
"I have not checked the coil. It is old and crusty..."

And you wondered why it was missing?

Milton · 08-03-2011, 06:32 PM

If the miss is intermitent check the shaft for any deflection also.

Purdy Swoft · 08-03-2011, 08:47 PM

I had a high speed miss a few years back and it took a while to find the problem. the problem turned out to be a new repro dist. cap body. The plastic or what ever the repro caps are made of was thin in the area above where the number 4 contact wire goes through the cap. At higher rpm it was crossfiring to the number 3 plug wire-strip through the thin spot in the plastic where the number three plug wire-strip passed over it. I only noticed the miss at higher speed. One night I had the hood up with the engine running, I reved it up pretty good and I could see the sparks and discovered the problem that had tormented me for a couple of months or more.

AstroZombie · 08-03-2011, 11:51 PM

Quote:

Originally Posted by 700rpm

"My cap is old and crappy looking, I was planning on replacing it anyway."
"The wear block on the point is badly worn. I planned on replacing points..."
"I have not checked the coil. It is old and crusty..."

And you wondered why it was missing?

Haha, yeah you're right! A lot has been falling behind recently. The money needed to fund my addiction hasn't been good. I'll do a legit "tune up" and see if it still misses.

Thanks guys, I appreciate the help.

AstroZombie · 08-03-2011, 11:54 PM

Quote:

Originally Posted by Purdy Swoft

I had a high speed miss a few years back and it took a while to find the problem. the problem turned out to be a new repro dist. cap body. The plastic or what ever the repro caps are made of was thin in the area above where the number 4 contact wire goes through the cap. At higher rpm it was crossfiring to the number 3 plug wire-strip through the thin spot in the plastic where the number three plug wire-strip passed over it. I only noticed the miss at higher speed. One night I had the hood up with the engine running, I reved it up pretty good and I could see the sparks and discovered the problem that had tormented me for a couple of months or more.

Repro parts just seem to be garbage. Thanks for the insight.

Tom Wesenberg · 08-04-2011, 02:48 AM

I've seen a couple distributor caps that short internally between the contact leads. That can be hard to find, since you don't see any sparks, and it may only show up at speed or under load, when the plugs need more voltage to fire.

Mike V. Florida · 08-04-2011, 10:56 AM

There was a thread on the old barn that reported "point bounce". It seems that the points spring was not very strong and when the engine sped up the points would no longer ride on the cam and would "bounce" over a lobe or two causing a miss.

John S · 08-04-2011, 11:28 AM

Quote:

Originally Posted by Mike V. Florida

There was a thread on the old barn that reported "point bounce". It seems that the points spring was not very strong and when the engine sped up the points would no longer ride on the cam and would "bounce" over a lobe or two causing a miss.

I can beat that story.
I once worked on a friend's '48 Chrysler Windsor 6. He had tuned it up at some point in time and it had not run right since. The car had a great idle but would not run over 1500 rpm no matter what was done to it. Over a period of years he had done a ton of work on this car including complete fuel system overhaul to try and fix the problem.
Well, turns out that the points were replaced with a national name brand (he still had the box with the old points) but there was no spring at all on them. Only the copper contact strip was opening and closing the points. I installed the old points and the car ran fine.

Mike · 08-04-2011, 11:56 AM

Check the amp meter and or loose wires going to amp meter!!

mike

Wick · 08-04-2011, 12:46 PM

Your Spark rod could be bent and is too close to the spark plug when your advanced all the way. Arcing will occure between the two. Also if you have just a key and the metal cable for the ingnition,the cable will sometimes arc against the head. look for this in the dark,motor running. wouldent hurt to wiggle a few wires and see if you get a arc. Ive been thru all of this.
Wick

AstroZombie · 08-04-2011, 03:08 PM

Quote:

Originally Posted by Tom Wesenberg

I've seen a couple distributor caps that short internally between the contact leads. That can be hard to find, since you don't see any sparks, and it may only show up at speed or under load, when the plugs need more voltage to fire.

I've been hearing a lot about this recently. Would it be better to buy a round distributor cap when I order a replacement? It would seem the fault is in the design of the standard winged caps. The car is a driver, so looks aren't as regarded as functionality.

Quote:

Originally Posted by Mike V. Florida

There was a thread on the old barn that reported "point bounce". It seems that the points spring was not very strong and when the engine sped up the points would no longer ride on the cam and would "bounce" over a lobe or two causing a miss.

Wow, that's a nightmare!!

Quote:

Originally Posted by Wick

Your Spark rod could be bent and is too close to the spark plug when your advanced all the way. Arcing will occure between the two. Also if you have just a key and the metal cable for the ingnition,the cable will sometimes arc against the head. look for this in the dark,motor running. wouldent hurt to wiggle a few wires and see if you get a arc. Ive been thru all of this.
Wick

I do have that, and I bet it's hitting the head. I'll have to check it out tonight and see if I can get any spark from the wiring.

Thanks again for the suggestions. I really do appreciate it.

Tom Wesenberg · 08-04-2011, 04:35 PM

I would not buy the round cap. I've never had a problem with the one cap I bought from Bratton's and the one cap I bought from Little Dearborn in Minneapolis. They both fit the metal body nice and tight and never had any crossfire.

Purdy Swoft · 08-04-2011, 05:34 PM

The problem with the round modern type cap is that you can't acurately measure and set the gap between the rotor tip and the contacts in the cap. I had one that was jumping about because the rotor tip was hitting some of the contacts in the cap. The rotor tip can be filed down but the gaps will vary, you can't see them to measure the gap.

08-03-2011, 04:24 PM	#1
AstroZombie Member Join Date: Mar 2011 Location: Armona, CA Posts: 61	My A misses at cruising speed... Any ideas? Just as the title says, I am experiencing a miss at cruising speed. Not anything I can really feel, but I can hear it. Car starts and idles perfectly, no other issues whatsoever. I have tried messing with the GAV, but there's no change. It has been getting worse the past few months then my el cheapo condenser died on me. I replaced it with a Henry condenser, regapped the points, and plugs last week. (hoping I would fix the miss also) It is running smoother than ever, but I still have that miss. It's frustrating, and annoying. Would anyone have an idea where to start searching? All ignition wiring is good Cleaned the carburetor out as well Plugs gapped at .030 Points gapped at .018 I'm clueless.... Last edited by AstroZombie; 08-03-2011 at 04:30 PM.

08-03-2011, 05:22 PM	#2
Gary WA Senior Member Join Date: May 2010 Location: Clinton,WA/Whidbey Island Posts: 4,105	Re: My A misses at cruising speed... Any ideas? Try 35 on plugs. and check gap on cap to rotor all four.20-30. may have a crack in cap. __________________ www.whidbeymodelaclub.com

08-03-2011, 05:41 PM	#3
John S Senior Member Join Date: Oct 2010 Location: Ellis County, Texas Posts: 337	Re: My A misses at cruising speed... Any ideas? Check the point gap on each cam lobe. It is possible for the distributor cam to be worn enough on one lobe to cause a miss. __________________ John _________________________________ http://www.dmafc.com/

08-03-2011, 05:43 PM	#4
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: My A misses at cruising speed... Any ideas? Have you checked coil polarity ?? Improper polarity can reduce secondary voltage by 15-30% causing a high speed mis-fire.. Check this;http://www.chicagolandmgclub.com/tec...neral/574.html

08-03-2011, 06:03 PM	#6
700rpm Senior Member Join Date: May 2010 Location: Portland, Oregon Posts: 5,906	Re: My A misses at cruising speed... Any ideas? Sponsored Links (Register now to hide all advertisements) "My cap is old and crappy looking, I was planning on replacing it anyway." "The wear block on the point is badly worn. I planned on replacing points..." "I have not checked the coil. It is old and crusty..." And you wondered why it was missing?

08-03-2011, 06:32 PM	#7
Milton Senior Member Join Date: Oct 2010 Posts: 837	Re: My A misses at cruising speed... Any ideas? If the miss is intermitent check the shaft for any deflection also.

08-03-2011, 08:47 PM	#8
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: My A misses at cruising speed... Any ideas? I had a high speed miss a few years back and it took a while to find the problem. the problem turned out to be a new repro dist. cap body. The plastic or what ever the repro caps are made of was thin in the area above where the number 4 contact wire goes through the cap. At higher rpm it was crossfiring to the number 3 plug wire-strip through the thin spot in the plastic where the number three plug wire-strip passed over it. I only noticed the miss at higher speed. One night I had the hood up with the engine running, I reved it up pretty good and I could see the sparks and discovered the problem that had tormented me for a couple of months or more.

08-04-2011, 02:48 AM	#11
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: My A misses at cruising speed... Any ideas? I've seen a couple distributor caps that short internally between the contact leads. That can be hard to find, since you don't see any sparks, and it may only show up at speed or under load, when the plugs need more voltage to fire.

08-04-2011, 10:56 AM	#12
Mike V. Florida Senior Member Join Date: May 2010 Location: South Florida Posts: 14,054	Re: My A misses at cruising speed... Any ideas? There was a thread on the old barn that reported "point bounce". It seems that the points spring was not very strong and when the engine sped up the points would no longer ride on the cam and would "bounce" over a lobe or two causing a miss. __________________ What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II

08-04-2011, 11:56 AM	#14
Mike Senior Member Join Date: May 2010 Location: ASTON, PA. Posts: 725	Re: My A misses at cruising speed... Any ideas? Check the amp meter and or loose wires going to amp meter!! mike

08-04-2011, 12:46 PM	#15
Wick Senior Member Join Date: May 2010 Location: Gwynn's Island Va Posts: 1,390	Re: My A misses at cruising speed... Any ideas? Your Spark rod could be bent and is too close to the spark plug when your advanced all the way. Arcing will occure between the two. Also if you have just a key and the metal cable for the ingnition,the cable will sometimes arc against the head. look for this in the dark,motor running. wouldent hurt to wiggle a few wires and see if you get a arc. Ive been thru all of this. Wick

08-04-2011, 04:35 PM	#17
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: My A misses at cruising speed... Any ideas? I would not buy the round cap. I've never had a problem with the one cap I bought from Bratton's and the one cap I bought from Little Dearborn in Minneapolis. They both fit the metal body nice and tight and never had any crossfire.

08-04-2011, 05:34 PM	#18
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: My A misses at cruising speed... Any ideas? The problem with the round modern type cap is that you can't acurately measure and set the gap between the rotor tip and the contacts in the cap. I had one that was jumping about because the rotor tip was hitting some of the contacts in the cap. The rotor tip can be filed down but the gaps will vary, you can't see them to measure the gap.