Chevy 307 crank for 327

[Beagle]

Bob, Crackerbox racing is a trip. Check out youtube, they're a riot to watch. This probably shows the proportions / locations a little better.



they spend a lot of time looking like this as I remember it..

[65RHDEER]

For the Boatjunkies in Bangshift!

These photos should explain the layout and yes that is the flywheel just behind the drivers back!

Photos aren't the best.







First day back on the water after 12 years. It took me 3 spasmodic years to get it there. I started from the bottom up, Rebuilt the trailer, re-glassed the hull, built a few new bits like the cav plate then got it on the water. Still to do is the deck and the interior but at least it can get on the water.

It's an early 70's fiberglass clinker that was originally fitted with a straight 6, someone before me put the SB in it.

[STINEY]

Neat!

I was going to comment on the no-snails thing, but I am guessing with that much drop from the manifolds and the flapper outlets right at the waterline reversion isn't a problem?

And an x-pipe. Too cool.



Mine is a '72 Wreidt Stinger 390FE 16' Jetboat like this one. Only not as purty. Not sure I am brave enough to eliminate the snails on it.




My junk behind Johns truck. He bought the 428CobraJet correct date-code for his mustang, I bought the rest.

[65RHDEER]

Water reversion isn't a problem, most of the marinised motors built here don't have snails.
The only time a boat here has snails is when the motor is from one of the big marine motor companies.

The X pipe takes a lot of the loud out of it, sometimes I think too much for a boat!

The jet is a good thing. Is your on the water or is it almost there???

Will it be running an FE or are you changing power plants?

A link to a blog on Australian ski boats, it's been going since 2012 and there's pages of good stuff to look at here:-

http://aussieskiboats.blogspot.com.au/

[STINEY]

Still a trailer queen......but you may have saved me a bunch of time by not bothering with finding snails, thanks.

Need to source a new fuel tank, this one is fiberglass and it turned to black goo inside from the ethanol in todays fuel. So pulling the deck and replacing the tank is in the cards.

Definitely keeping it FE. Have all the parts and they are polished nice. Just needs that tank and reassembled with some spit polish.

That link is great. I can spend days in there!

[Beagle]

can you flip FE headers? I'd point them up front, do a u bend and go over the transom. Kids need to learn shiny means don't touch at some point...

[Deaf Bob]

Yes! FE exhausts are flippable..
Did that with old 352s and 390s in derby cars..

[STINEY]

Ha! They actually came with tubing that does sorta that. Bends upwards (no flipping) and over transom with SuperTrap spark arrestors. They capped off the thru-hulls with plumbing rubber caps hose-clamped to the inside, left the flappers alone.

Was just a touch too ghetto for my tastes......maybe I am getting old?

Maybe not. Will have to give that setup a second look.


Anyways, to un-derail the thread - the 327 I have that wants a C3 Corvette home, it had the cast crank replaced with a steel OEM one by my buddy who I bought it from. He was nervous about winding a cast crank to the heights he liked on a regular basis, and went steel flywheel and blow-proof bellhousing at the same time. Guess he saw something come apart because it was cast, I forget the details.

Anyways, it was no big deal for the Bowden's machine shop to get everything in line again.

[65RHDEER]

After one of the Power Pack heads dropped a valve seat near the end of last season I've gone down the road of building this 327 for the boat.
Got the 4" bore block, 327 pistons, new set of rods and the 307 crank. All off to the machinist, crank gets cleaned up and onto balancing to find that is to light for the rods and pistons. The machinist tells me it will need 125 grams per pin to come into balance, total of 500 grams to be added to the crank. This surprised me as there is only .175" diameter difference between the two pistons, but that difference works out to be 62.5 grams.
I measured out 63 grams and it's not much at all, you'd be lucky to tell the difference if you were holding a 307 piston in one hand and a 327 in the other.
The machinist has a 27 crank that's going on the balancing machine tomorrow to see if that has enough weight.

[Loren]

Am curious as to the original reason for using the 307 crank, not a forged 327 unit...although the cast one should certainly live, in a medium-rpm boat.

[65RHDEER]

The reason for using a 307 crank is that there is a lot more of them in Australia than 327 cranks.
Turns out the pistons that were purchased for this were very heavy at 900 grams, we got hold of a 327 crank and that didn't have enough weight in it for these pistons.
I have now ordered a set of Speed Pro H660CP hypereutectic pistons for it, they weigh 766 grams and so should be good with the 307 crank.

[anotheridiot]

The reason for using a 307 crank is that there is a lot more of them in Australia than 327 cranks.
Turns out the pistons that were purchased for this were very heavy at 900 grams, we got hold of a 327 crank and that didn't have enough weight in it for these pistons.
I have now ordered a set of Speed Pro H660CP hypereutectic pistons for it, they weigh 766 grams and so should be good with the 307 crank.

I am just a little confused on the balance questions. If you get all the pistons and rods the same weight, arent you balanced again?

I know you are talking about more of a rare piece here, just wondering.

[cstmwgn]

I'll chime is (as I have had a few beverages) - having all the components weight the same (rods, pistons, bearings, pins, clips) is a requirement for a well balanced combo - the reciprocating weight (bob weight) is critical part of engine balancing. The weight of the pistons (and rods to a lesser extent) are the most influential in the bob weight calculation and the resultant need for heavy metal.

[65RHDEER]

There is weight in the counter weight of the crankshaft that is traveling in the opposite direction of the weight of the piston, pin, rings and small end of the rod.
For balance you want these wights to be the same so they cancel each other out.