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Thread: bOre VS stROke BBC TECH

  1. #1

    bOre VS stROke BBC TECH

    okay a guy i work with happened to mention to me the other day he has a 402 bb lying around that he wants to sell for 500 bucks heads and all says it has a forged crankshaft etc etc. anyway i was thinking about stroking it out for a future motor by putting a 4.250 stroke crank in it which would make it the effective cubic inch of 461.2 which a .030 over 454 is 460.6 would this combination run as fast or neck+neck with a 454? i realize the smaller bore would hurt the flow on the heads and the longer stroke will wear out faster.

  2. #2


    etc. etc. is a very big range on a 402. What I mean is, what 402 is it? All 396/402's came with forged cranks, into the mid 70's anyway. If it is a 2 bolt block, save your money. They can't be bored past .030" (402), .060" (396) unless they are sonic checked for core shift/wall thickness. And then you still have weak 2 bolt block. If it is a 2 bolt block it has oval port heads. Not a bad little street engine with the right cam and manifold. But not worth spending much machine work/parts on. Now, if it's a 4-bolt block, that's a different story. #1, it could be worth something to a restorer (depending on what it came out of). #2 those blocks also came with nitrided cranks, forged pistons, and big port heads. Those blocks can be bored (if sonic checked) to 4.250" and then you've got something.

    Good luck, Dan

  3. #3
    Senior Member DYNO OPERATOR
    Join Date
    Feb 2006
    VA Hospital, Dallas, Tx (214 302 1924) cell-972-464-7400
    Dan gave good advice.

    Besides that $500 bucks for a 396/402 even with heads and crank in my opinion is not a good deal for anyone but the person doing the selling. Not popular. Not wanted. Not much potential. This all means that in the performance world and in the market of buying and selling it is pratically worthless.

    If you want an economical building block to use get any 454 block and a set of either 049 or 781 oval port heads. Then you have something with potential for not much cost. A 4.250 crank can really wake that one up. That block is strong enough to handle just about all you would expect of it.

    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.

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