Is it possible to take a 1 piece rear main seal 350 block .030" over with a 4.00" stroke crank to yield a 408? I saw in JE/SRP's catalog that they make a piston for a 408 with a 4.030" bore, but I had no idea a 4.00" stroke could fit in a 350 block. I understand a small base circle cam would be in order, along with only a 5.7" rod, but I would think you'd have to really grind on the block a lot! Let me know what you think! :)

Don't know about the (late) 350 blocks, don't use 'em. They go in the 400's (we've done 'em without cement). Another consideration is this, a 350 block with the 4.000" stroke and a 5.700 rod (we've never tried that either, as I doubt it would clear on the down-stroke) has a horrible rod/stroke ratio and an even worse bore/stroke ratio. You could fix part of the problem with a 5.850"/6.000" rod, but you'd be still stuck with the bore/stroke ratio. Thanks, Gary in N.Y.

I don't think you can put a 5.85" or a 6.0" rod in it, with out the compression height on the piston being dangerously low.

As for the bore/stroke ratio, I don't think its that bad. Ford guys build 408's all the time and they get awesome results. I've just never seen a bowtie guy do it.

You want to get that serious,, they make Motown blocks that require no grinding.. $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$.

I'm not that serious, but I have 2 blocks just sitting here taking up space. If I use one then I want to make it worth while. Maybe a 391 or 396 would be cool. :/

Sure, they used to do this with 283's before the bigger SB's came out! Called it a "4x4" motor!!

Like the lovely Miss Dolly say's, "5 pounds of sugar in a three pound bag"!!! He, He!!

I figure you would have to start with a crank that has 350 crank size counterweights, stroke it a 1/4" and then heavi-metal it for balance, then rod notch the block everywhere, plus use the small base circle skinny cam as mentioned to get it done.

Plus use as long a rod as you can to still create a half decent r/s ratio as mentioned too...

(This is why the bigger 400 crank and block is mentioned b/c of balance and more clearance)....

A whole lot easier to do with an aftermarket block, standard deck or tall deck....

pdq67