Hemi vs Non Hemi

Packman88

Member
Hello all,
I am new to the predator engine and have been seeing some post on hemi vs Non Hemi. Can anyone tell what if any the difference is between the two?

Thanks!
 
Hemisperical combustion chamber vs wedge/bathtub shaped chamber.
Slightly different diameter cam bearing size .
 
they have different tapers on the flywheel, cam journals different size by .006"? hemi has shorter spring pockets that make going into coil bind a real issue with high lift cams and strong valve springs... since they cant come up with ovate valve springs (oval spring to prevent going into coil bind so soon). hemi has canted valves that are more apt to run into piston on HIGH lifts ("high"... is...???? ) so ppl "eyebrow" the piston to try to keep valves from kissing head.

some think that the NON hemi head on the HEMI engine is the ticket as the HEMI has a flattop piston whereas the NON hemi has a dished piston... but a .009" metal head gasket stock. the HEMI has a .045" fire ring head gasket... that can be swapped with .009" head gasket shim . my HEMI piston was in the hole .017" so with a .009" head gasket shd have the minimum head /piston clearance of ~.030" ... some say .025" minimum piston/head clearance? UMMV (ur mileage may vary)

the crankshaft apparently flexes when screaming the motor and the dipper on the connecting rod hits the bottom of the motor, breaks off, taking the rod cap with it and ruins engine. some cut 3/8" off the bottom of the stock dipper to avoid this when they open up the motor to remove gov/oil sensor. make oil holes bigger on stock rod so gets MORE OIL so rod wont spin weld itself to the motor for lack of lubrication... hone out big end with bottle brush hone a LITTLE BIT for more oil clearance? polish crank journal and piston pin wth 2000 grit sandpaper to make them SMOOOOOTH. $65 for billet rod is probably a good investment as if rod goes... it ruins motor.
 
On the stopwatch I've measured very little difference - and those differences appeared to be more due to production tolerances than head design. But that is with box stock engines. However, a few years ago I did see somebody who was running an early version of the Predator (not sure what its part number was, but the owner said he bought it when they first came out, and they don't sell that version any more) that did seem to be down on power.
 
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