max stroke ??

[Tiger]

Hi all,

I have a 400cid sbc block that is half hard block filled that I'd like do do something with and I therefore wonder: what is max stroke with steel rods in a SBC400 block ??

3,875" or maybe 4"??

or should I get a 3,75" cranck and be happy with the 406?

Thanks
André

[Lowend]

You can do a 3.875" stroke but that is honestly the limit for a factory 400 block.

Someone is bound to hop in here and say that a 4.25" crank will fit. They are right it will physically fit, but the factory blocks are not strong enough to resist the flexing caused by these mamoth cranks.

[Tiger]

So making a 434 is out of the question with a standard block then.

what would you go for?
1. 3,75" making it a 406 cid
2. 3,875" making it a 420 cid
3. sell it and go for a dart or motown right away?

If I build it, should I go bananas eg. all forged H-beams stc or just cast and some nice rods and pistons and make a cheaper one?

André

[TurboLark]

So making a 434 is out of the question with a standard block then.

what would you go for?
1. 3,75" making it a 406 cid
2. 3,875" making it a 420 cid
3. sell it and go for a dart or motown right away?

If I build it, should I go bananas eg. all forged H-beams stc or just cast and some nice rods and pistons and make a cheaper one?

André
Depends on your power goals. I went with the Dart block to save problems when I decide to up the power.

[jjump59]

Stock block can be modded to live at 550 hp or so. in the long run its better to start with an aftermarket block. you can spend 1000.00 building the stock one or spend 1800.00 on a good aftermarket.

[justanova]

I have seen a 434 built on a stock block by a dirt track racer friend of mine, I believe it was a 4" stroke. he used H beam rods from eagle, and said he had to use a small base circle camshaft to get everything to clear, not to mention there wasn't much of the bottom of the block after all the machining. He said he would never build a 434 on a stock block again, too many exotic parts had to be used and the cost per HP gain was too much,

It can be done, but probably not worth it.

my .02

[Lowend]

I would go for the 3.875" myself - but know you are probably going to have to buy custom pistons

[kball]

I agree with turbo lark. I went through this before. Stock 400 blocks are inherently weaker than other stock blocks, or I should say have weak points/ cracking at the steam holes beside the head bolt holes mainly. And I never really was a fan of bearing spacers. I'd either build a 383 or buck up and get a good block bow-tie , dart and save headache in the long run.