stock stroke 340 pistons.

Been looking all over and am trying to find 11 to 11.5 compression pistons. Everything I have seen are 9.5 to 1 or 13.5 to 1. The pistons are going with a 60cc combustion chamber. Trying not to special order anything. Thanks

What bore, hyper or forged? Closed chamber head?

I had to order custom pistons for my 340's, couldn't find any off the shelf pistons that would work.

Google TRW 2216 IIRC and you can use those. Are they the lightest piston out there? No, but they aren't as bad as most think. You should be able to find them in any oversize up to .060 if that's what you need.

With those Pistons you can set your combustion chamber volume and then mill the dome down to get the CR you want.

Also you'll need to stick the piston deck .045-.050 OUT OF THE BORE to use the least dome you can and get some quench.

Use an .039 gasket and only mill the heads far enough to get .050 or so piston to head clearance (you can squeeze it to .040 but you gain nothing and you'll still have some room to mill the heads later if you need to). You should be able to get what you want with a dome of .150-.200 and get the CR you want.

If you’re planning on using a closed chamber head and zero deck ...... you’ll either need to get the heads down near 55cc’s, or use a piston with a net dome volume of around 0cc’s(with 60cc heads).

Open chamber heads will allow positive deck heights...... but then you’ll have to balance the chamber volume, gasket thickness, quench pad area depth, valve pocket volume, etc.

The easy button is a 4” crank.

IIRC my 340 with 55cc chamber Edelbrocks and .030" over Diamond flat tops were 11.4-1.

The tops of the Speed-Pro L2316F pistons are about .500" thick. You could easily cut off the .045" or so to get a zero deck. That would take some weight out of them as well. I seem to remember they are around the stock 340 piston weight (~750g).

The first incarnation of my 340 used L2316’s.

With the fairly good sized Crane Hyd cam I had for it, I discovered the valve pockets weren’t generous....... and since I had the short block all assembled and didn’t want to take it all apart to flycut the pistons, I ended up having to install a smaller/wider cam in the motor.

My point is....... the stock replacement style pistons aren’t as accommodating for bigger cams as what newer design HP pistons would be.

If you’re not planning on putting too much cam in it....... it probably won’t be an issue.

The TRW’s are heavy...... about 890g piston and pin.
A set of SRP’s would be over 200g lighter .... each(almost 4lbs lighter for the 8).

I wanted to keep machining to a minimum with trying to go with some pistons and milling them down. More I see it a 416 or a 372 might be a cheaper option then trying to achieve what I want to do. I am looking at a fairly roudy solid roller camI (NT/EXH - Dur @ .050” Lift: 258°/262° RR: 1.5/1.5 Gross Lift: .624”/.627” LSA: 108° RPM: 3000 to 7000 Redline: 7500) Would also like to keep the rotating mass down too and make it live.