How about 421?

[dfhotlm33c]

So, it seems that stock block 434 isn't a great idea, unless you spend a significant amount of money to prep it, in which case an aftermarket block is better anyways. So, how about going the 3.875" stroke route? Will a 421 have a better chance of survival? I have two, 2 bolt 400 blocks and a four bolt 400 stock block. Again, planning 13:1, AFR 220 ported head wet sump engine. Just looking for advice/experience regarding what a stock block, with splayed caps, would support. Thanks

[SLM98]

If you add up everything you spend on a stock block, caps and machine work you are not too far away from the price of a SHP block. I would spend the money now and avoid the headaches later.

[JustAddDirt]

I would not personally throw that big of a crank in a stock block.

3.75 stroke
3.625 stroke
is what I would install
depending on what weight of car you were putting it in

[hpmaster]

For years we ran 383's, 406's and had problems until the Dart blocks came along. After buying a crank, rods and all the stuff for a good motor I rather put it in a minimum of SHP, personaly I have never used one, and better yet a Little M. You lose a block you lose everything in it.

[vanness9595]

I just broke a brand new 421 in a stock block. It was race prepped with main studs and the webing where the mains bolt in broke destroyed a 1600.00 lunati crank cam 2 carrillo rods and 2 je pistons bent some valves in head. Lesson learned hard way

[c.mac.4]

I just broke a brand new 421 in a stock block. It was race prepped with main studs and the webing where the mains bolt in broke destroyed a 1600.00 lunati crank cam 2 carrillo rods and 2 je pistons bent some valves in head. Lesson learned hard way

Was it a stock 4-bolt block or a converted 2-bolt? We ran 430s on methanol for years in converted 2-bolt blocks, NEVER had bottom-end block issues.

[Mosidebite]

Tried the 3.875 and 4.00 everyway posiible. It always failed in a stock block. That's been my expires ce.

[bob75]

you have to cut out to much of the stock block for clearance on a 4in stroke ,wont last,spend the money on a shp block you will save in the long run.

[Brian Gray]

Its because you think you need 4 bolts in the mains. That's where you lost with the stock block. I have 0 issues with 2 bolt stock blocks. Now none are in a late model turning 8500 rpm but many 7800 rpm mod motors.

[Brian Gray]

I will offer some advice That you probly won't take or believe but if your building this for a stocker or modified your missing the boat big time. Think more bore less stroke. You'll win on durability and driveability.

[nguyenvinh2]

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