Engine and Transmission Tech

Hey man. The valve reliefs are cut at something like 7.5º if I remember right. Our heads have a really shallow valve angle. COOL. I used the head gaskets as a template and cut the heads the old fashioned way then cc'd the volume. The difference was minimal at ≈ 1cc.

The machine shop told me that I shouldn't notice a big difference in balance because the amount of material removed was small compared to overall weight and equal amounts were removed from each piston.

On the quench: You mean you don't think it will matter on our engine? or that .050" isn't enough?

I assembled the engine for the last time yesterday. I couldn't torque the rods because I didn't have the stretch gauge handy. That will have to come later. I was able to check the actual final dimensions of everything. I initially thought the pistons were going to be shorter at .012 above deck but when everything was assembled for the last time I ended up with .035 above deck. Right where it was when I started:

Head Cc: 46
Piston Cc: 4

Deck: +.035
Quench: ≈ .038

Head gasket dia: 3.77"

Bore/stroke: 3.74 x 3.4
Intake valve ABDC: 68º (@.050 + 15º) (adv: 71º)

CR: 12.6:1
DCR: 9.54:1 @ 1000 ft. (9.72:1 @ sea level)

Not huge compression but I'm happy with it. The pistons are not forged so it's just as well I'm not pushing it there. Since detonation is so ulikely with E85 I could get away with lighter/weaker pistons. We'll see how it turns out. It could be they don't last and I'll start this process all over again. LOL!

So no more waffling. This is where the numbers are. My course is finally set.

Nic, since your pistons are not "race" I'm thinkin you have pin offset? Know how much? This will reduce "I" loads at turn-around and lateral thrust. I'm sure you ring-gapped for Hyper,(hotter)piston per mfg'r? Your pistons should have minimum rock at reversal. Some of the reasons for squish and quench areas are to reduce end-gasses from going-off prematurely, (detonation), also to provide beneficial turbulence. The more one increases gap clearances the less effective they become. Personally, I prefer less than.05", aluminum rods not withstanding and considering rpm/stretch. I hope all of your effort is returned in "the loud pedal", roverman.

Boy me too. I fought with the engine all morning with a game I like to call the Heli-coil suffle! SUPER frustrating. I'll start a new thread for that. I'm sure we'll all chime in. LOL.

Pin-offset. Is that were the pin centerline is above the shear surfaces? I think so... Never checked this though. I did gap the rings VERY carefully. It took a few long hours. I gapped them to each respective cylinder and kept them with the pistons the cylinders where blueprinted to. Hopefully that will pay off a little.

Damn.. If I wasnt sick Id invite myself over for a look.. :-)

Nick, Art is talking wrist pin offset.

Ah I get it. Since I machined the top of the piston the offset is different now. Hmmm. I hadn't thought of that.