Crude Intentions

iTrader: (1)

Mildthunder on here Joe has some tiny little 468s with some 420s on top making over 800 reliable horsepower. Runnin a straight bottom 38 fountain to 96 mph. What's your goals?

ezstriper

have run cast cranks in drag race BB and beat the crap out of them, never heard of a crank failure than did not come from something else 1st, have run them in marine apps as well no issues

B38

If I can get 87 mph I would be happy. Respectively 80 + is my goal. I need to cruise at around 70 mph. I currently full wicked at 70 mph running 28 bravo 1s at 5K rpm. Probably go 30 - 32 p with new setup. Maybe run her to 5200 rpm.
the rub is with the 496 crank kit in a 7.4 block, Only savings is the block. The rest of the internal parts are shelved. Just sell my shortblock complete and use money towards 540s.
ezstripper = thanks for the tip on cast, figured that's why most crank kits are cast. My gen 6 blocks with all cast junk will not pop with 5lbs boost.

B38

I have a total of four 7.4s. Two gen 6 currently in boat. Two gen 4s old school 420s with all forged goodies. Gen 4 where going to be the rebuild. Now I think sell all four engines now. Keep my external parts and blowers for 540s. The rectangular heads I'm keeping from the gen 4s.

Baja Rooster

iTrader: (1)

That sounds like a wise course of action and probably cheaper in the long run.

getrdunn

iTrader: (7)

One of the keys to cast not turning into a bad day is the best balance job you can get. I ran the 454/330 on roads years ago and beat them like a red headed step child at 5,700/5,800 rpm constant. Never ever a problem and that was with 3/8 rods with are 2000 bolts. If I built marine engines for a living I wouldn't advise unless in anything than stock applications but...

I haven't run a cast 4.250 crank though so I can't comment on that but if you make sure rotating assm is balanced well and keep the r's down you should be fine. BBC just doesn't sound right anything under 5,600.

MILD THUNDER

iTrader: (3)

why not freshen the 420's bottom ends, put a decent pair of heads on them, and some blowers

airjunky

iTrader: (2)

I assume the gen 6 is not the mag motor.
Still , a couple of plug and play gen 6 mpi motors should be worth something.
If your blowers have the nads, those gen 4 mags with a careful bottom end refresh and some good heads gaskets and the right intercoolers and ex. manifolds will throw down some serious horsepower

SB

iTrader: (1)

I'll bet $1000 that GM factory modular cast iron cranks are better than cheap hunk of schit cast steel china cranks. Only person I knew to run a 4.25 cast steel crank, after me jumping up and down saying no for months, had many issues with it - balancing $$$$, bearing issues, seal issues, and finally built better motors.

The cast steel chinese schit that has been doing pretty well are in the much smaller stroke and less journal overlap and less reciprocating weight small block chevies. Popular in mild 383 builds.

MILD THUNDER

iTrader: (3)

The 4 inch stroke, GM Forged steel cranks are tough as hell. They were the chit back in the day, before all these companies came out with "stroker" cranks. Whats good for a guy like me, is you can find good clean used GM steel cranks, for a song these days. Everyones upgrading to "496" stroker motors. Usually, they would have been better off keeping the stock cranks and rods, and focusing on cylinder heads, camshaft, induction and exhaust, but hey, everyone wants to think cubic inches rule over everything else.