Can't say exactly how much different it is between them. Just that it can't be made as thin up there, and the hole adds to destabilizing the valve train. Then having something shaped like that, and that thin threaded into the port is going to leak, and crack eventually. When you have to mow a hole all the way through, top to bottom, then plug off the top, why expose yourself to all the potential problems if you're starting from scratch? Starting with a wedge block, i'd still take the preds over the 600.

As for blocks, no one is going to do it for a while as I understand it. AJPE says they may be in the mopar block business soon, so maybe. I can take a standard deck, and plate it up, but then I'm still stuck with 48 degree lifter angles. A .5 up deck with 45 degree lifters really helps, and I don't want to do it any other way.


I thought Digby's stuff was forced induction.

When the summer is over, if blocks aren't available I may just redo the one I have as an NA. More stroke, +.03 bore, more valve, an NA cam, more compression, thinner rings with 20 pounds less tension, lighter piston, and pins, lighter rods, way way more port volume, shorter runner manifold, big bore carbs, take the nitrous taper out of the quench, correct the lifter galley oil waste, and get serious about weening it off oil. Not having to contend with the nitrous will make it reasonable to drop the pressure in half.

I've swapped my car from a 2 to a 3 speed, so the motor could stand to be more peaky now.