Here's the story. About 12 years ago my son and I got ahold of a 67 and put a OHC6 motor in it. This was when Primatech first came on line with parts for the OHC6. Anyway, 12 years later (a few weeks go) my son is cruising through Texas from Arizona when engine quits in a puff of white smoke coming from under the hood. So, we tow it home, pull the plugs for a compression check and notice that five of the six plugs have melted. Compression check indicates a blown head gasket. So, rather than sink a bunch of money into the 6 cylinder, he's thinking of swapping out for a 400. Looking around, I notice this motor is kinda hard to come by, so I'm wondering about a chevy 350 which is readily available. Also, since we don't have a 400 motor now, we would have to get all the add on's which won't come with the motor, if we can even find one. How available are these parts. Any thoughts and advice would be appreciated......... PS: Why the plugs melted after a 700 mile drive with no problems is still a mystery to us...But then again, we're not mechanics...
Most folks here cringe on hearing you're thinking of SBC power. The coolest thing about Pontiacs is the Pontiac drive train. Otherwise, just drive a Camaro or Nova. There are plenty of Pontiac 400 motors around. Just a little pricier for parts. But worth it.
Maybe the ohc is still good and just needs a rebuild. They are good engines. With any luck the pistons aren't melted and it was just a head gasket that went. You have to take out the engine either way, why not open it up and see how much damage there is. It may be cheaper to rebuild than replace it and all the attached components.
Melted plugs, too high a tip temperature.
Running a car to lean can heat up the tip, running a plug with too high a heat range can heat up the tip, high outside air temp can heat up the tip, detonation can really screw things up. Too high a heat range, high outside temp, running too lean, high compression ratio, too much spark advance and low octane fuel can all lead to detonation.
The spark plug heat range is how much heat it can conduct away from the combustion chamber. The lower the heat range the more heat it will transfer. It's not the temp of the spark, just how much heat it will conduct.
OK. I can see I crossed a line with the SBC comment. LOL. So, please disregard. We might be on the lookout for a 400 pontiac motor. The good news is we put a new head gasket on the cammer and it seems to have done the trick. Compression between 160 to 170 on all cylinders. Intake manifold has a leak now so will have to reinstall, but I think the rest of the motor survived the spark plug melt down...Time will tell..Appreciate the comments and I'm glad to find out that a 400 motor might not be too hard to find after all...