well i've out alot of advise thru the fast few years and now could use some opinions..

the old 472 , 460+ .060 over.. is have old age problems. with over 120,000 miles on the motor now at almost 10 years old it has developed a miss that comes and goes. i've changed just about everything, cap, wires, plugs, carb twice, module, voltage regulator, coil, distributor 2 times an older one a had that was still ok and a brand new one, compression is fine, but still has a miss. now sometimes it's not there it runs just great but other times it runs like crap. i have noticed that the spark plug gap on number 7 cylinder has been closed 2 times now. that is the unbelievable part. do you think i have a connecting rod going south?? it does smoke alittle on that side of the motor. the reason i say unbelievable is i can put an older set of heads on the ground and look at them and can see with a straight edge along the bottom edge can see that it is atleast about a 1/4 of an inch from where the piston would probally be at top dead center to where it would make contact with the spark plug electrode. i've never had a rod try to break up on me before, you can sit there in the truck and when it's running good rev it up to 3,000 r.p.m and still runs good sitting in the driveway, but when you start to drive down the road that is usually when it starts to happen. it has been a good motor but maybe it has seen better days... C.J.

 

Maybe a valve hanging up, weak valve spring, on the erratic missing.

Could be pieces of carbon closing the gap on the plug.

 

F.W.I.T. I had an intermitten miss on my truck. Most noticable between 40 and 60 mph. I was planning on getting a new carb. anyway so I didn't mess with the old one. After putting the new carb. on the miss went away. Starts right up an idles smooth. Perhaps you carb is the cause of your miss. Just a thought.

 

no it is not the carb, i wrote in my post that i have ysed 2 different carbs... i know it is not fuel and i know it is not spark. so i guess that would only leave something to do with the piston or the rod. for somereason the gap on the plug keeps closing off, ............

 

[updated:LAST EDITED ON 28-Dec-02 AT 02:36 AM (EST)]I agree with superdave on this one. I think you will end up having to tear it down. At the very least re-do the heads. If your piston, rod or crnk were going on that cylinder you would hear it for sure.

PS. be sure you have no forign material in that cylinder. One time I tore an engine down and found a wingnut from the aircleaner stuck between he valve and seat. The owner thought it would just pass through...... it didn't.
Nick from the frozen north
1974 F-250 4X4
soon to be 429
dana 60 front and rear

 

 

Just a thought...Did ya check the neg cable on the battery or maybe a ground strap?