Started on the BBC, 427 or 454... ?

[fine69]

It was relatively temperate out today, so I started to clean the big block heads... Holy crap these are some heavy muthas!:eek

The casting # is 336781. They're open chamber heads with oval ports. The date codes are L773 and K1973. I believe these are from a 1973 454 motor. I am going to have these machined with 2.19" intake valves and 1.88" exhaust valves.

Since I ruled out the 502, and decided to stick with my Mark IV block, I'm still undecided on which way to go, 427 or 454.

I also have two crankshafts:

• a 427 crankshaft that came out of a 1969 Corvette 427/390 (casting # 6223). The journals will need to be polished - but I got it free!; and also
• the beautiful LS-6 454 crankshaft (casting # 14015445) that I bought from ZL1Johnny. This has been reground 10/10 and is in pristine condition. Of course the 454 rotating assembly would need to be externally balanced. Is that really a big deal to do?

Any comments or suggestions are welcomed.

Thanks.

Ralph

 

[TimAT]

That's a tough one. The 6223, 427 crank is a forged 1053 steel crank. The LS-6 crank is very likely 1053 steel too, but is also tufftrided. BUT! did the .010/.010 take the tufftriding off? Maybe. No idea how thick it was. Or really if it is a heat treat process that covers the whole crank. You may need to do some reasearch on that process.

As far as balance- unless you are planning on a full tilt race balance (not needed IMHO) just use a 454 balancer/flywheel for the 454 crank. The factory thought that was close enough. Same for the 427- just use the correct stuff.

Your head casting number comes back as Open chamber 73-85 113cc.

http://www.nastyz28.com/bbcmenu.html#crank

There's no replacement for displacement.


I've got a 454 in the vette right now- If I could figure out how to drop a tall deck block in there with no more hassles than the standard deck block I'd shoot at 700+ cubic inches. I can get 632 with a short deck, but for the difference in $$, I'll run the 454 until it dies.

 

[fine69]

Here are the heads...

I shot some PB Blaster in the valve ports to help keep them from rusting up.

 

[Ed's 1970]

454 all the way. U can even build a 496 quite easily! Just use a 4.25 inch crank with possibly a little clearancing on the block, guys are building these instead of the smaller motors now. I myself started out with a bowtie block with a 4.5" bore, could build a 509 or 540. Chose 540 because it is a bigger engine. Crank fits in my block with no clearancing and lots of room!