What compression would a 60.5cc head give on a 383 stroker?

I know gasket thickness & piston type (dished/flat/domed) plays a big part of it, but can anyone give me any estimates based in different pistons/gaskets etc.?

 

Never mind......

I found http://www.angelfire.com/fl/procrastination/motor.html and by playing with gasket thickness & dished pistons I'm looking up off of Jefs.....It's not looking like a very streetable engine!

Flat tops gave 14:1! 12cc dished give 12.2:1

It would definately need a thick gasket and seriously dished pistons to work as driver duty on the street, even under a carb as planned.

 

I'm starting to doubt that sites calculator......Anybody have any input on this?

 

60.5 cc with conventional 5cc valve relief flat top gives 11.53 to 1 compression with a .040" gasket, zero decked block.

For aluminum heads, thats streetable with 93 octane, a big cam and a good combustion chamber. Keep the motor cool, run some colder plugs and it should live on pump gas.

To be safer, use 7-12cc relief/dish piston.

7cc flat top gives 11.26 to 1 using same conditions above.

12cc dish gives 10.63 to 1.

Depends on what cam you plan on running and what heads they are. Newer heads have some good chamber designs and can tolerate abit higher compression.

 

Thanks.

The problem is, that this block was prepped years ago along with the crank, heads & such, but never assembled. And it has just sat indoors.....Very minor surface "rust". Really just an orange looking coating.

And the heads are OEM iron 3884520 "Power Pack" heads. I have no idea what size valves are in it nor if the combustion chamber has been opened up or if the heads have been decked.

This isn't my engine, just doing some research for the owner.

 

Well in this case, the iron heads will want a pretty large dish piston. I know they have a few 16cc pistons but thats still 10.2 to 1 roughly. MAY work on pump gas with large cam.

To be in mid higher 9 to 1 range you would need around a 20-22 cc. Not sure they make that off the shelf. JE has 28cc dishes for blower setups but that gives under 9 to 1 and would be rather lazy. The 16 cc could be your best bet, just have to watch out for detonation. Carb may beable to get away with more since the fuel has cooling effect on the intake air and may help supress detonation. A healthy cam will help to bleed off some cylinder pressure and give lower dynamic compressions.

 

Download the CR /DCR calculator from here. ( bottom of page )
http://members.uia.net/pkelley2/DynamicCR.html

Have found it to be more real world accurate than most others out there especially on the DCR calc