Hey guys, I've got a chance to buy a 416 stroker motor that was started but not finished as the poor guy passed away. Seems like a very good start to a nasty Camaro stomper. It has all the block work done (cleaned, magged, oil galleys cleaned, bored .030, align honed, ARP main studs), an Eagle 4340 forged 4.00 crank, Eagle H beam forged rods, Ross 4.070 forged pistons (12.5 to 1), MP 280 .509 solid lift cam and lifters and a MSD electronic distributor. Pistons seem a bit high on compression for a street car. I would rather get back to 10:0 or 10:5 to 1. Would I have a hard time selling these pistons?? They are $600.00 in Summit. Brand new in the box. Could I get $400.00 for them do you think?? Also is this cam ok for this set up. I have a 6 pack set up I was going to use on my 340 that I would use now on this. What do you think???????????????

Can you mill the dome off the ross pistons, will the top still be thick enough?

You can mill the dome off but, it would only knock down the compression about a half a point according to the compression calculator at Summitracing.com. I plugged in all the numbers there and came up with 14+ compression ratio. Even went back and rechecked several times, used different cc heads etc. Always very high.

Run propane

If you are getting a good deal on the motor, and its still a good deal if you have to buy new pistons, id go for it. Like most things you never know what something is worth to anyone else but ebay could be good place to get rid of the pistons. I have not run the calculations but depending on the choice of heads, head gasket thickness, rods they may be just right for someone.

See if E-85 fuel is available in your area..

105 octane..

How do you know you have 12.5:1 compression? I don't see any mention of flat top, domed, what the cc's of the heads are or anything. A bit more info would be appreciated.

A 416 has about 853cc swept volume per cylinder. To get r compression ratio, one divides the swept volume by (r-1).
So to get 12.5:1 you divide 853 by 11.5 = 74.2cc above the piston. For 10.5:1 it's 853/9.5 = 89.8cc

So you can see you need a way to subtract 15.6 cc. BUT, you still haven't told us about block deck height, head volume, etc.

Just saying a piston is "12.5:1" doesn't tell us much.

R.

cranking compression is more important for pump gas
anything under 190 psi should be good for street use...

Ross #99788 4.2cc dome pistons. 4.00 stroke 4.070 bore .018 out of hole. 65cc heads .040 head gasket=14.02 cr on the summitracing site. Milling off the dome only lowers cr to 13.23. Even going to 72cc heads(x heads) with dome milled off only lowers cr to 12.13. My conclusion:These are race pistons, not for street. Who would want stroker race pistons?? Most anyone building a stroker would buy a complete rotating assembly. I guess I'm going to build my 340, its mostly done already.