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Thread: max stroke ??
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10-29-2004 #1
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max stroke ??
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
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10-29-2004 #2
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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.1971 Camaro, 383 stroker ~500HP,M21 Trans with lightened flywheel. All Sorts of Auto-x Goodness in the Suspension. 12" Brakes ->SOLD
But ask me about my 2004 STi Auto-x car...
Just call me Brett
10-29-2004 #3
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no 434 then
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
10-29-2004 #4
Starting The Transformation
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Depends on your power goals. I went with the Dart block to save problems when I decide to up the power.
Originally Posted by Tigergutt
1965 Buick Skylark
10-29-2004 #5
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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.
10-29-2004 #6
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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 .0272 Nova SS, on the back burner for now.
current cruiser: "The green machine"
'70 Impala 4drht, 26K original miles, 2" drop springs and large swaybars, drives pretty good for a land yahct
in the middle of an ls1 swap, but thinking about changing directions to a duramax diesel swap.
10-30-2004 #7
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I would go for the 3.875" myself - but know you are probably going to have to buy custom pistons
1971 Camaro, 383 stroker ~500HP,M21 Trans with lightened flywheel. All Sorts of Auto-x Goodness in the Suspension. 12" Brakes ->SOLD
But ask me about my 2004 STi Auto-x car...
Just call me Brett
10-30-2004 #8
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400
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.
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