There may have been a change/modification in terminology since the days long ago when I spent more time on engine configurations; mostly these days I lean towards running 'factory stock' (but hopefully high performance) engines on the street. I never heard the term 'dish pistons' until the factory began to reduce compression and kill performance (mid-late 70s). Dish pistons were used to increase compressed volume and reduce compression in those motors.
I just searched for and found a fairly good article (by Wiseco - a piston mfg) which explains significant detail related to piston crown design.
https://www.hotrod.com/articles/insi...ons-explained/
Obviously the piston crown design is complicated and varies by what type of engine and induction is planned. He makes a statement, which should be obvious, that most desirable is a 'flat top' piston, because the maximum combustion force is directly applied to downward motion of the piston. You have to think about head combustion chamber shape/volume, quench, head gasket thickness, etc when choosing your pistons (or let the engine builder choose it for you based on your objectives).
+12 cc = dome, -12cc =dish not that complicated to me. We put a dish 383 in a 89 TPI IROC with vortec heads. Ran 13.0 and still knocked down 20 plus mpg on highway. I believe FE Fords had dish pistons in the 60s. Diesel's before that.
that's the definitions I've always used as well, Mark... A 'dish' piston ADD volume to the combustion chamber, whereas a domed piston reduces the combustion chamber volume.
What was bothering me was Mike55 stated intention to use 12cc dish pistons and getting a CR close to 10.5... I thought the CR would be much less than that (but I was thinking of a 350 ci engine.. Mike55 was referencing a 383.. so I went into my Compression Calculator and increased the stroke to 3.75 and the bore to 4.030 to get the 383 cid, and sure enough a (-)12 cc DISH piston with 64 cc heads, 0.020 deck height, 0.016 gasket (steel shim) will result in a chamber volume of 5.10 in**3 and a static CR of around 10.4...
So Mike please excuse my confusion, as I have never built a 383 and wasn't thinking about the additional 1/4" stroke and it's effects.. I think the use of DISH pistons in such an engine very likely is one of the reasons that those engines are so powerful!
PS. I've got a std 350 block (with bad forged crank) in my basement.... maybe I should consider buying such a 383 stroker kit for it..
So.... now that are all singing from the same hymnal, has anyone used the CompCams XE274 in their 383?
Ive used Comps 292, but would not put a flat tappet cam in
any rebuild, unless it was completely stock.
The 292 I used was yrs ago and it bent pushrods. Have two
383s now with roller cams.
Solid lifters are cool.