patioman

Hello Again,

I have 302 V8 from a 1985 Lincoln Continental that I have dropped into a 1949 Ford F1 that I am restoring. The engine was rebuilt at a local machine shop. Here are the engine specifics:

Cylinders bored 0.040 over
New stock pistons
Stock heads with 120lb valve springs
CompCams Thumpr Roller Cam with 0.531 lift intake, 0.515 lift exhaust
Funnelweb 7-1/2" rise intake
600cfm Holley carburetor
HEI 50K Coil Disributor

I originally began with stock Autolite plugs. I start the truck occasionally to move out of the shop or a quick trip around the block. I haven't put it on the street yet. It began popping and backfiring on one cylinder and spread to 2-3 more cylinders. I tested everything I knew to test and finally bought a new set of Iridium plugs which cured the problem. However, a couple months later the problem started again. It got so bad the truck won't start now. I pulled the plugs and cleaned them but that didn't help. I pulled the coil, ignition module & pickup coil from the distributor and had them tested at the auto parts store. All checked out OK. I have since put new Accel wires on, tried a new coil in my distributor and finally bought a new distributor which is installed now. If I test a plug straight from the distributor I am not getting a spark. The plugs are gapped at 0.045. I tried one of my old Autolite plugs and I am getting a weak spark. I know if I buy a new set of plugs my problem will be cured once again for a short while. Since I have had 3 different new coils installed, I know it's not the coil, besides I have a new distributor in now. What is causing my plugs to go bad?

Thanks for your help......

patioman

I'm going to assume that the coil in my first distributor was bad causing my Autolite plugs to go bad. When I replaced them with the NGK Iridiums, it ran OK until the bad coil eventually ruined them. No matter how many new coils I put in, even a new distributor, it will not be OK until I get a new set of plugs in. I will do that this weekend and hope and pray my reasoning is correct.

Bert

We haven't had that problem. I hope you're right too. Good luck and let us know the outcome.

__________________
Bert

patioman

Well I put new plugs in last night. Went back to stock Autolite plugs. She fired right up. Does however sound stronger and the idle was actually higher than before telling me it is getting a lot more spark than before. I am going to replace my power valve today. I am swapping out the number 65 for a number 45 because of the low vacuum as a result of my high lift cam. I am currently running real rich so I will lean out the carburetor today as well. I think my old plugs fouled to the point of no return. At least by cleaning with a simple wire brush. I will put them in a spark plug cleaner and try them again later. I guess I will wait and see if the new plugs last longer.