383 or 400 Block for stroker motor

[Garys1969RR]

As outlined in another thread, my race only 496 has a case of excessive blow by, in that the valley pan has pushed up against the bottom of the intake manifold, due to excessive crankcase pressure. So I am going to take it apart, and use the internals to build another 496 or 512. It has the 4.25" crank, and I have both 383 and 400 blocks laying around. So to use that 4.25" crank in a 400 block, I would need new pistons. I could probably use the pistons that are in my current 496 in another 383 block, with new piston rings. Just trying to figure out if it"s worth another $700 for 400 size pistons. That only gets me another 16 cubic inches. Is the 400 block that much better than a 383 block? Anyway, just kickin ideas around. Any thoughts/experience on this? Thanks for your input and ideas.

 

[Ironbuilt]

Definitely go with the 400. Much better block for a stroker.

 

[m79ded]

Definitely go with the 400. Much better block for a stroker.

Unshrouds the valves better due to bigger bore.Stronger mains as well

 

[mopar 3 B]

Unshrouds the valves better due to bigger bore.Stronger mains as well

How one figures the mains are any different 383-400 is beyond.my understanding.
With the stroker crank the mains will change anyway.

 

[mopar 3 B]

Definitely 400. Please dont screw up another 383 block.
Also better figure out what went wrong. No reason to make the same mistake twice.

 

[Garys1969RR]

I didn't build this one, it came in the car, and no telling how many runs it has on it. We've put it thru 25 or 30 hard runs. I prefer the 400 block, as has been suggested. Definitely a stronger block.

 

[Garys1969RR]

How one figures the mains are any different 383-400 is beyond.my understanding.
With the stroker crank the mains will change anyway.

The 440 Source website points out the advantages of the 400 block over the 383. There is Alot more iron cast around the main bearing support, and the 400 is much stronger in this area. The early 72 block ending in 230, is the strongest and most sought after. I havent ran across one yet, but they are out there. I believe the main bearing journals are the same size in the 383 and 400.

 

[Garys1969RR]

Just got done finishing up the Holley 750 installation on our Tunnel Ram equipped fire breathing 496. Will be transforming this into a 512, or another 496, due to there being excessive ring blow by in this 496. The reciprocating parts, crank, rods, roller cam and heads will all be re used. If I use the 400 block I have on hand, all I should need is new pistons to match the bore size, as well as the other bottom end parts, rings, gaskets,

etc. Here are a few pictures of what it looks like now. One more trip to the strip this year, to see how it runs with the 2 Holley 750s, then we'll pull it out, tear it down, and go from there.

 

[moper]

If it was me, I'd replace the pistons either way. I'd sonic test the blocks U had, and use the one that's in the best shape. Your experience should tell you the 400 might be better, but you don't need it. You need the tallest piston you can get in the package. So take the one with the thickest walls, and order new pistons for it. If the rods you have require a piston with a ring support rail, I'd get shorter rods to let the piston be taller.