Can I use flat top pistons with 64cc heads on a 400? Or should I go with the dish pistons? I'm looking at vortec heads with the dishes or maybe aluminum heads with flat tops if I can. the reason I'm rebuilding it is it beat it's self to death with 64cc iron heads (World Sportsman II) and too high gears (spark knock finally broke the top ring lands on a couple of (stock cast aluminum) pistons. I changed the gearing from 3.73 to 4.56 so no more lugging. the 350 in it now is pretty stout but a 3/4 ton 4x4 needs more torque than the 350 musters up. No pulling, no hill climbing or mudding, just normal use but some 4 wheeling when necessary. MSD ignition, Edelbrock EPS, Holley 670 streeetmaster, 700R4 trans with the 4.56 gears. I'm using a comp Extreme 4x4 cam right now but leaning towards something else if you have any suggestions to get an almost 6000 lb truck moving AND get 20 mpg (thought I'd throw the last part in for a laugh)
depends on what compression ratio you're looking to gethttp://www.kb-silvolite.com/calc.php?action=compthis might help
I'm looking at no more than 10:1 for use with pump gas. It is a truck after all.
I would think you would be safer with a dished piston, especially since you are using pump gas. Aluminum heads would help if you go with the flat tops. I would only use 93 octane and never lug the engine.20 mpg is possible if you only run downhill or you run with a tailwind of say 100 mph ..... maybe 125 it is a heavy truck. I laughed at a previous post where one guy was told a 4x4 weighed around 3400 lbs.Maybe one of those little Toyota crappers but not a real truck.
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Dished pistons is the safe way. Like Dave said use only 93 Octane nothing lower in octane. Go higher (Racing Gas)you will see a nice difference in power.