1988 OMC Sterndrive plug amp piston problem

"I have had this boat since br

"I have had this boat since brand new. I put a four barrel intake and carb on it shortly after purchase. The first motor I burnt a hole through a couple pistons. Put heavier pistons in and ended up burning the top of the block out of the cylinders. Put a different engine in and melted the center out of the plug and sucked a valve into the head. I have a low to midrange performance camshaft and an automotive intake. I know that I need the marine intake, but will that solve the problem. When it starts to go bad, it will backfire into the carburetor. The plugs start out black and then burn out the centers. This happens mainly on the center four cylinders. Anyone with suggestions?"

yea what motor is this?

yea what motor is this?

The motor is a 5.7 liter 350.

The motor is a 5.7 liter 350.

"who is doing the build for th

"who is doing the build for the motors may i ask.

What sorta oil pump you running, as example: a high volume pump, stock pump?
What dizzy you running?"

"I am doing the rebuilding. I

"I am doing the rebuilding. I have rebuilt several motors, but they were automotive. Circle track race engines, street rods, cars, trucks and heavy duty engines. I have a high pressure, high volume pump.Not sure its an oil problem. I was thinking it may be a detonation or lean fuel mixture problem. It seems to be excessive heat in the combustion chamber."

I was using a higher rpm camsh

I was using a higher rpm camshaft and it seemed to last longer using roads lifters

"the hv pump will suck your pa

"the hv pump will suck your pan dry, and thats why your not getting oil to the critical parts.

You should have used a stock oil pump. and i would have used all stock internal parts.

here is a link, i just posted also to another thread here, will explain better.

http://forums.iboats.com/showthread.php?t=251215&highlight=oil+pump+high+capacit y%2C&page=2"

"You should tune your fuel sys

"You should tune your fuel system correctly so you can quit wasting engines.
You seem to be aware of your lean condition, do you think a marine intake will cure that? Re-jet, I'd start 4 steps richer since you are melting things."