I am considering which pistons to use in my mostly street driven 440 based 493 stroker Challenger. I will be running Eddy RPM heads stage 3 ported and milled to 80cc. A 440 Source stroker crank and rods. With a small solid roller comp cam details:
Cam Style Mechanical roller tappet
Basic Operating RPM Range 4,000-7,200
Intake Duration at 050 inch Lift 262
Exhaust Duration at 050 inch Lift 262
Duration at 050 inch Lift 262 int./262 exh.
Advertised Intake Duration 308
Advertised Exhaust Duration 308
Advertised Duration 308 int./308 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.575 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.575 in.
Valve Lift with Factory Rocker Arm Ratio 0.575 int./0.575 exh.
Lobe Separation (degrees) 110
Intake Valve Lash 0.020 in.
Exhaust Valve Lash 0.020 in.
Grind Number CRS-308R
I am looking at Diamond pistons part#52415. They will give me 10.6:1 compression with .012 deck height or 10.86:1 compression with zero deck height. Will this be too much compression for 92 octane? Would you zero deck it or run the .012 in the hole. Any oppinions are greatly appreciated.

Your combo seems a little off in ways. Odd mix for a street engine. I don't think you will need a 7200 red line with a 493 either. Cometic makes a hg for any thickness you need. As low as .027 thick. you loose around 1 point in Comp with aluminum heads, so I have read here.

With the big cam the higher 10.8x compression ratio with zero deck should work fine. I'm running 10.2 and zero deck with a smaller 242@.050 cam and no problem with detonation at all.

With standard port heads and 493 ci it will be done by 6000 RPM regardless which cam you use.

A comment on cams. Everybody's needs and preferences vary. You have choosen a big cam for a mostly steet driven car. You will get the drawbacks of a big cam - low vacuum, power brakes won't work without a pump and soft performance in the common street RPM range of 2000-3500. Getting decent performance will require a high stall convertor that will make a lot of heat and burn a lot of gas. With standard port heads you won't get the benefit of a high RPM top end charge.

You may enjoy your car more with a smaller cam that gives better mid-range performance... the push you back in the seat torque that makes BB wedges fun. Something in the 240-250 degree @ .050 range.

With the 250 ish cam you would probably be OK with the 10.87 CR. With a 240 ish cam, CR may be a little high. Adding deck clearance to drop CR won't help either since it takes away the benefit of quench. If you do want to drop CR, a litle bigger dish is much better.

I run a very similar cam(Comp Cams lobes, 260 @ .050 intake, 266 @ .050 exhaust, 108 LSA in at 106.5 now ) in my 518 low deck stroker, 4.375 bore with a 4.300 stroke. It is a pump gas motor with a little overe 10. 8 to 1 compression now with a set of Indy SR M.W. ports, it use to be 10.29 to 1 comp. ratio with the Eddy RPM heads and six pak, that cam worked really well pull really well with the Eddy RPMs and six pak to over 7600 with out straining To answer your question on the comp. ratio I would stick with the piston down in the hole and go with Edlbrock head gasket that is(use to be) .031 thick What type and thickness head gaskets are you planning on using now?

I was going to use the Eddy RPM heads on my 493 and have them CNC'd. With the 440Source flattop piston I would have been in the 10.5 to 11.0 area. But I changed and went with the Indy EZ heads with smaller 75CC chambers. So I had to use the 440Source dished piston and I ended up with 10.6 having my pistons very close to zero deck as they came out about .006 down. My EZ heads are opened up to Max Wedge ports but I wanted that as I use a good size cam. Its a flat tappet custom grind from Dwayne Porter and it is 264 & 270 @ .050. With 1.6 rockers it has .624 & .630 lift with a 110 LSA. I have it in at 106 and I love the way it works and sounds. I just wanted to run 10's in my 63 thru the pipes on 92 pump and drive it to the track which it has as it has run 10.70's. I would shoot for a flattop piston at zero deck and you should be in the 10.8 area with 80 CC heads. Good luck , Ron

i ran that 262/.575 cam in a 11:1 440 on the street with a 3500 stall. it worked fine. i also ran the 244/.550 cam in that same motor (actually both cams ET'd about the same). the .550 cam was probably a little better in the 440 on the street. but in the 493 that .575 cam will work just fine.

put it at zero deck or even a couple thousands out with a 0.040 gasket.

I am going to run the Felpro 1009 .039" head gasket. Thanks for all the advice, it really helps.

Here is my experience -

493"
flat top ross pistons ( .004 in the hole)
eddy rpms 84cc
should be about 11:1
610 lift flat tappet/ 268 dur.
34 degrees total
.039 gasket (Edelbrock)
ran it on 92 pump for a while (all summer racing) .

popped a head gasket---could have been anything , but...
I replaced the gasket and started running 50/50 blend gas , 110 + 92 pump = no problems after that.

hope this helps

I have a set of new Ross flat tops but I am reluctant to use them with my 80cc heads. I am trying to stay away from racing gas and the extra cost and hassle. That is why I am looking at the Diamond pistons. Thanks for your input.

With that cam and your planned CR, you should be fine on pump gas, IMO.

that 7200 operating range for the cam is likely sized based on a 440, for an SR the lift is a little short for that @.050 duration but it'll make plenty of torque and power. It's probably a street endurance grind which to me is perfect because with a wedge head the peak lift isn't as critical as long as your in the sweet spot of the head flow (85-95% of peak).

Should work great, I'd look at the Indy dual plane (383man, BSB67 and myself all run them on ours ) and look close at a custom calibrated pro-systems 1000HP or similar. 10.86:1 calc'ed should be fine and a little lower than what I typically run on a 500 incher.

Thanks Wise. I am also going with 1.6 intake rockers.