My Turn for a Cam question - 318 Build

MileHighDart said

They are indeed .030 in the hole. They are not stock pistons. They were replaced the first time I built this engine about 17 years ago. At the time, I let the machine shop get all the parts, they told me they couldn't find a "mopar" piston the right size, with full floating pins. So what they put in it is pistons that have 2 valve reliefs, but they are in the wrong place to actually do any good as valve reliefs. I don't know if the're chevy pistons or what. I'll post a pic later to show what I mean.

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Cool... at least the shop was creative in getting the CR up. Per what I can find on the Egge version of these (L2050), these pistons should actually be about .010" below the stock 318 LA deck. So you might want to check again. The reliefs look a mite bigger than 5-6 cc's....I'll guess maybe 8 cc's total? Now you're up a tenth or so more for SCR. But still could use some CR help for the altitude.

Now for sure I would be checking the piston to valve clearance with a new cam and those pistons! Hmmm, are the cam and timing chain still on? If you tossed one head back on and lightly bolted it down, with clay on the top half of one piston, and put together a set of the pushrods and a pair of good lifters and the rocker set for that cylinder, you could rotate the engine by hand and see what you have for piston-to-valve clearance now with the present cam lift. (You may have to fill the lifters with some oil to get them to open up the valves right.) Then you would at least have some idea on the clearance you might have with a new cam. Durations and timing will have an effect on it too, but at least you will have a starting point for understanding the clearance.

MOPAROFFICIAL said

Poly pistons. HEAVY

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Do you have a weight on those babies, MO?