Car runs great cold but misses at idle after warming up

[Tgriffin91 27]

Title basically says it all. I have a stock 302 C-4 combo. When I first start the car up everything is smooth and runs great but after it gets up to running temperature it sounds like one cylinder begins to miss. I checked the spark plugs yesterday and they look good. I checked the points gap and that looked ok too. The rotor cap looked like it was only hitting the front edge, which would indicate timing? I played with that a bit adjusting it a few degrees up and down (missing my timing indicator) and that didn't help.

I'm thinking at this point it may be bad points?

 

Does anyone have any suggestions?

 

Thanks! 

-Thomas

[Brian Conway 264]

Suggest you start pulling plug wires to locate the exact cylinder, plug and wire that is suspect. Could be as simple as a bad plug wire. Brian

[Tgriffin91 27]

Forgive my lack of knowledge. Pull them and inspect, or pull them with the car running?

Plug wires seem fairly new, but to be honest I do not like them much so that could be the problem.

[69RavenConv 286]

I think Brian's suggesting that you unhook one at a time while it's running. If nothing changes, that cylinder, wire, or plug is suspect. Of course, I would inspect each wire first for obvious problems. My center coil wire retreated into the boot such that the boot was firmly attached to the distributor cap but the wire was not -- the car ran like crap because the spark was arcing from the cap to the wire.

 

Also make sure your choke is operating properly and it's opening when warm.

[Tgriffin91 27]

Ok that makes sense. Thank you for the clarification. I will check them out. I did adjust the carb so it is opening all the way at running temp. Thank you for the suggestions.

[Gomach1 12]

Possible cracked cap opening up when engine is warm, try running car at night and check for arcing, spray cap with wd40 when running and missing to see if it clears up. You could could also have a plug wire breaking down when warmed up. Also try spraying inside of cap with wd40 and wipe off excess then run, this will eliminate any carbon tracking (doubtful this is problem but you never know)

[J's69Mach1 17]

I had a problem before with a very tiny hard to see, hairline crack on spark plug porcelain. Spark plugs were new but I double checked and found that hairline crack on 1 spark plug.

[Tgriffin91 27]

I checked the wires and they look alright. Like I said they are not my favorite ones. Currently I have the 8mm accel wires. I ordered a pertonix module to get rid of my points. I've been waiting to get one a while now and finally found one on sale. Hoping that will help with the issues.

What wires would you guys recommend for replacements?