I have not been able to find after market forged cranks for the 425. How much power can a stock crank handle?
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I have not been able to find after market forged cranks for the 425. How much power can a stock crank handle?
The stock 401/425 crank and rods are forged. They were often used in supercharged engines over 1000 HP. The cast pistons are the weak link in the Nailhead.
Mickey Thompson made a stroker crank for the 401/425 that you see for sale on the web every so often. I had seen a custom stroker 401/425 made by by King recently. I attached a picture of that crank. It is in the 470 CI range.
The M/T and King crank are cast and are not as strong as the stock crank. If you want to build a stroker. have a machine shop offset grind the crank and run BBC rods. You will get int the 450 c.i. range depending on the bore.
Some have used the 401/425 cranks in 455 Buicks to be able to spin the engines to 7 & 8000 RPM's. There is someone now that will offset grind a "Nail" crank for use in another 455 Buick engine offset grinding the rod journals to 1.88", Honda size, for additional cubes.
Tom T.
To All:
I must be missing something.
Why add the extra Cubes when the heads don't flow well with 425 cubes?
Are there any new/re-designed Heads out on the Market? (Please say yes!) ;-)
Thanks,
Ty O'Neal
they may not flow well, but more cubes is still more cubes.
plus, you can always solve the flow problem with forced induction.
Go back to my post. I was talking about using a "Nail" crank in a 455 Buick!!! When you force induct the intake the exhaust now becomes the problem. It just cannot get out fast enough. Will make some serious power & torque to 4500 or so RPM's though.
Tom T.
Why mess with a good design????
well, partly it was to move to lightweight casting techniques. i believe the tall deck Nails weigh north of 700lbs compared to the ~625lb of the BBB.
also, they converted the big block to the integrated aluminum timing cover, oil pump, water pump like the small blocks had.