Pieces of steel in cylinder??
I got the Sealed Power H814CP pistons, they were recommended somewhere on this thread as high compression pistons.
OK that was what I was thinking. But go back an you will see that they are characterized as the highest stock-ish CR pistons.... not 'high compression' pistons.
So, running some numbers, your static CR with these pistons, stock 318 heads, unmilled, and a .028 thick head gasket will be right around 8.2:1. No high. Slap on typical 340/360 heads, and now your SCR is right around 7.8.... right in stock /6 territory.
Now what will really set your lower RPM performance is going to be something called dynamic CR (DCR) which accounts for the cam's effects on effective CR. The bigger you make a cam, the lower the DCR will be and get that too low, and the low end torque for grocery-getting type of driving will go into the toilet. Not good with a heavier pick-up truck in grocery-getting service.
Since you are going to put in another cam, then it is time to look at that and make a sensible choice. You can easily get the low RPM toque LESS than that of a stock 225 slant-6 by getting too big of a cam... and with this lower level of static CR, it won't take much.
So you are not going to use the 318 heads? Is there a reason? Honestly that is not making sense to me. You're gonna have to stick with a smaller cam to keep the low RPM from not dropping out of sight, and with that, the breathing of the larger heads is not of any big use.
For what you want to do with this engine, with these pistons, with the future build coming at some point, and to keep your daily driving torque up, this was recommended: 318 heads shaved to get the CR up.
- mill heads .040" or .050" and use the standard Felpro kit head gaskets and those same pistons; this will push CR up over half a point from the stock level
Hope this makes some sense.
