'59 Plymouth Forum

We overhauled my 230 engine it runs and sounds really good until get to 60 mph. The timing is correct got a new vacuum advance,took dist all apart everything looks perfect. A thought i have is, the machine shop decked the block and milled the head. The head had been milled before because when i got the car it had a blown head gasket. My thought is the compression is changed to much. Does anyone have any advice on this? Thanks.

There's a good chance that the compression ratio change could be causing the pre-ignition. Try a higher octane fuel, if that doesn't help, retard the timing some. Pinging will eventually harm the engine if it persists.

---John

Thanks John, i tried prem. fuel but problem still there. Is there a shim or possible 2 head gaskets may fix it?

2 head gaskets may lower the ratio enough to help, but retarding the timing slightly would be my first direction.

---John

I would now try disconnecting the vacuum advance and see if eliminates the ping. With L head engines it is hard to increase the compression to a point that premium fuel would not help,

Great advice! It's entirely possible you're getting too much advance, or earlier than you should.