Mild built 383 spark plug suggestion

Its a 383, bored .040, flat top pistons forged crank, 10.1 compression

-stock 452 heads

- MP .474 cam

- Headers

- Dual plane intake with 750 preform carb

- MSD ignition and Mallory uni-lite distributor.

- 3" all the way back

I'm just wanting to dial it in. Strictly street car. Hasn't seen the road in years so I'm sure it will need tuning. Always ran autolites, but they fouled out real quick. I've read resistor and non resistor plugs but not sure what the differences is. Any knowledge or suggestions appreciated.

if your fouling something like an autolite 85 then you'll probably foul anything else out there. find out why the plugs are fouling first.

I run Champion J12YC in my 383. Non resistor with copper core. Stock plugs were J11Y and these are as close as I've ever found to them.

I'm working on that. Bought a new carb with four coroner mixture screws. I had bad fuel contamination issue that I've addressed. It would plug the inlets of the carb. New fuel system from tank to carb. Just need a base line and a plug I can stick with while I get it where its good.

What carb. brand and part number is th new one? I would start with the stock jetting and put in a new set of Autolite 85 and set the ignition timing at 34 degrees total revved up beyond 4500 RPM, once I got the timing set I would check the timing at idle RPM, if it is less than 14 BTDC I would have the distributor recurved to get between 14 and 18 BTDC at idle and no more than 34 total revved up

Proform brand new, 67200.

I don't know or have I heard of any results on the Proform carbs, Sorry Let us know how that works out

FYI, A 383 with flat top pistons and stock 452 heads will have a lot less than 10:1 compression. More like 8.5:1. The domed KB400 piston would be close to 9:1 with that head. That said, any plug with close to a stock heat range should work.

there've been some good plug threads in the past if you can retrieve them with the general concensus that quality of most of em has deteriorated (like most else). As said I'd figure out if it is gas or oil fouling & if gas then check the choke and or the AF ratio. Timing in the ballpark. For oil, new valve stem seals (if that is it) or maybe a rebuild (read "breakin secrets" at www.mototuneusa.com