Making power out of the 318
Ok why do you say flat tops not a dome piston? because some of the forms i have read say the domes are the best for the 318 i am just curious
Flat top pistons have the best flame propagation. The dome can get in the way of the flame propagation. Have you ever tried pouring a bit of gasoline in a line on a driveway or sidewalk. Make certain nothing that could catch fire is close. Cap your gasoline can and put about 10 feet away. Then light one end of the spill. You will see how the gasoline burn spreads. In the cylinder is quite similar, it is a progressive burn, not an explosion. If it explodes - detonation, bad and expensive things follow.
The decision between flat top or dome is reliant on the cylinder heads available or chosen. Open chamber heads do not promote cylinder mixture motion which aids a quick and efficient burn. If you watch DV's porting videos, he shows how to promote swirl, which is mixture motion. Those factory open chamber heads are prone to dead mixture motion which allows detonation.
Quench heads have a flat area that is level with the head gasket surface. Generally you want about 0.040" clearance between the piston top and that quench area. As the piston approaches TDC it squeezes the air/fuel mixture out of there at high speed, generating mixture motion and a quick burn. A thought, look up Somender Singh "groove technology". A local here uses it on his sled engines and swears by it.
With some heads you just need to use a dome piston, but keeping it down to say 0.100" is best for flame travel. Considering you can still drive with the leaning tower of power it may be wise to keep your eyes out for a good set of aluminium.heads with tight combustion chambers of about 60cc, and then chose the pistons. Remember, form a plan first. Getting good heads with small combustion chambers is part of the planning. Used parts are out there and someone on here may have what you need. Swap meets will be coming up soon. Get there EARLY as the good stuff gets snapped up early.
I hope that helps some.