[wbferran]

I am searching for an annoying miss on the 351W. new valve job. rebuilt carb. good vacuum, no apparent leaks. wondering about possible spark issues now.

the plug wires are old, Autolite Pro Fit. is there any way to check for proper resistance? how often should they be changed out? i suppose if I could find an oscilloscope somewhere, that might help out.

appreciate any ideas.

 

[1970fastcat]

Do you have a multi-meter? If so, use the ohms feature and put the leads on opposite ends. Most plug wires have between 150 and 1500 ohms of resistance per foot. If any of them have more than 4000 or so then it is likely bad. They all should be pretty close to the same reading, taken into consideration the length.

 

[C Gauch]

Back when I drove these cars everyday I would change the wires every year or two. Plugs, cap, rotor, points & condensor once or twice/year.

 

[wbferran]

Back when I drove these cars everyday I would change the wires every year or two. Plugs, cap, rotor, points & condensor once or twice/year.

well, i have owned the car since 1979, but i don't get to drive it every day. i see from my records the plug wires were installed in 1999. that's a lot of years, but only 26,000 miles. i am grasping at straws trying to find this miss. since i have just about written off vacuum leak as a cause, i am left with fuel and spark. electronic distributor in 2000. what is the average life of the plug wires?

 

[Harvey]

Some plug wires last a lifetime some not so long. The ends might get corroded or burnt? When was the last time you changed the spark plugs? Didn't by chance drop one did ya? also might have had one dropped in the store or prior to you getting it? If you pull them all can you tell which one is missing? Fouled? or darker than the rest?

 

[wbferran]

Some plug wires last a lifetime some not so long. The ends might get corroded or burnt? When was the last time you changed the spark plugs? Didn't by chance drop one did ya? also might have had one dropped in the store or prior to you getting it? If you pull them all can you tell which one is missing? Fouled? or darker than the rest?

plugs are new following the valve job. pulled them for a compression check and they all looked fine. i have a feeling the miss is more sinister than a simple plug, plug wire or vacuum leak.........

 

[Bad69cat]

You'd be surprised at how much havoc a vac leak can cause....I'd start double checking that agian.

 

[catman]

I am searching for an annoying miss on the 351W. new valve job. rebuilt carb. good vacuum, no apparent leaks. wondering about possible spark issues now.

the plug wires are old, Autolite Pro Fit. is there any way to check for proper resistance? how often should they be changed out? i suppose if I could find an oscilloscope somewhere, that might help out.

appreciate any ideas.

Try this http://www.mercurycougar.net/forums/showthread.php?28622-Spark-Plug-Wires&