Building a Johnson 70 hp Race Motor

[hoodooguru]

We have decided to have one last race (this sunday) on our pretty standard 75hp Stinger then get a motor built within 3 weeks for the next race in a month.
I have done alot of reasearch here and elsewhere on mods we should do.
We are getting a mid 80's big block 1000 cc power head so our torque / power will have a good bump from the smaller 75 hp block.
We hope to have a dual carb front end.
We plan to:
Do intake and exhaust porting / enlarging / smoothing
Deck the head for higher compression
New rings / honed
Better pistons and rods (still to sort that out)
Lightened flywheel
Boyeson power reeds
Dual carbs with ported intake manifold
2 inline fuel pumps
Finger porting

What other tricks are there we can do to stay under 1000 cc for our class of racing?
We have to have a standard exhaust but are there any other mods we can do to it?
Any suggestions on pistons / rods? We want to get around the 110 - 120 hp range.

Cheers

Jon

[scc82]

I would not use the boyesen reeds. There are better reeds out there, try call Chris Carson @ 1800-329-2725 and he will get you set up. Also all the 3 cylinder omc have three Carbs on them. I think you mean two barrel Carbs?!

[olmo40]

It will all be pointless if your setup and prop isnt right :confused: been reading your other posts .I did a "Wingboat" in OZ circa 1990 i think ,it was basically a standard motor on a paper weight boat .

[hoodooguru]

Our setup and prop is now correct.
And I don't have a wing boat.
Yes - Dual barrel Carbs.

[LightNBug]

Due to the exhaust restriction of the 56 cu in, with no practical way of improving it, I would use the single throat carbs and intake. I would also use the permanent cast block from 86 & 87. The exhaust flow is better and the boost port velocity is greater. These are just my opinions based on actual experience.

[mcyama]

What type of fuel can you run? do you have any restrictions in your class? I ran methanol and bean oil for years on roundy round boats for years. It was the winning touch. thanks martin