426 Mega Block Numbers

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J

Jim1175

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New guy here, I have a question for the board. Here is my story, I bought a 69 dodge dart with a 440 and 671 Blower for my son`s 2nd birthday. I smoked the motor racing it and bought a 426 Hemi to replace it. I had big plans for it then Life happened. Now about 15 years later I ready to get back on track. I`m in the planning stages and trying to figure out what block I have. I pretty sure (from Research) I have a early Mega block, Not sure what year or part number. Does anyone know anything on this block. Thanks

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It does look like an old Mega Block, does have the dash M casting number, and is clearly finish machined as a Hemi block with pushrod clearance, inner row head studs, and original style engine mount pads. So, the only thing we don't know is if it's a street block with water passages between the cylinders or is it a siamese bore version. If heads or core plugs are still off/out, just look through the coolant passages to see if there is a passage between adjacent cylinders for coolant. There were several part numbers available, but they varied based on siamese or non-siamese, original style or 440 ears for engine mounts, and which bore diameter it was finished with.
 
Bobzilla said:
It does look like an old Mega Block, does have the dash M casting number, and is clearly finish machined as a Hemi block with pushrod clearance, inner row head studs, and original style engine mount pads. So, the only thing we don't know is if it's a street block with water passages between the cylinders or is it a siamese bore version. If heads or core plugs are still off/out, just look through the coolant passages to see if there is a passage between adjacent cylinders for coolant. There were several part numbers available, but they varied based on siamese or non-siamese, original style or 440 ears for engine mounts, and which bore diameter it was finished with.
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mega block. All gen 2 hemi blocks I ever saw HAD RL cast in the side of them. Looked like a 12.5 to 1 engine w/ extra water cooling in the center freeze plug hole. Aftermarket rocker arms and stands, roller lifters . Dang it nice to see the inside of one again! Now about that drain plug hole !
 
Looks like an early 90’s replacement 426 Street Hemi block. Its not beefed up around the lifter bores like the later mega blocks
Probably P4529850
 
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Am I the only one to question why a 2 year old needed a blown 440 Dart?

I mean damn, I need one now and I'm not much older than 2.
 
And those pistons don’t jive with that blower either
 
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