Re: prop sugg. on a 84 272 ls w/ 5.7 twins?
 

MUCH BETTER!!!!!!!!!!!

You still have 19% slip though. You should be at 15% at a minimum with the 3B Cleavers. You are running right were you should be with the 5.7 L motor at the 4800 RPM at WOT. I think you should try to test some Mirage Plus 21P props and see if they bite a little better.

Julie

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?
 

Can anyone give me some pointers on swithing the gears around in the drives to make the port drive turn LH? I have no Idea how to tear apart a drive though I am very mechanically inclined do most of my own work on my trucks and hot rods. Is it something I should take to a shop?

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?
 

You have to buy a counter rotating alpha drive. they are very hard to come by.

Re: ok new #'s
 

This may sound like a stupid question, but I had a friend that made this mistake last week...
Are you sure your gps is reading mph and not knots/hr?
Your boat should go 60mph with 21p at 4800 engine rpm.
53knots is about 60mph...

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?
 

Just installed a counter rotating drive on my 1986, 24ft Daytona. Went from 20p aluminums to 23P Mirage. Runs straight and handles much better. GPS at 61MPH at 4400 rpm. Have stock 260hp 5.7 w/ alpha I drives. Got a new drive on Ebay for $1600. Now need more power.

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?
 

to make an alpha counter rotate you switch to a counter rotating lower.......you do not have to change the whole drive...............doug

Re: prop sugg. on a 84 272 ls w/ 5.7 twins?
 

Thanks guys I will start searching on ebay for a counter rotating lower.

Re: ok new #'s
 

your alphas arnt going to limit you ......they are actually faster than a Bravo due to a smaller gearcase and less mechanical drag from smaller/lighter gears and shafts.......there are no shorty lowers available only a VERY rare "Alpha SS" drive from Mercury that is 2" shorter than a stnd Alpha.....from what I understand (Ive never seen one) you cannot modify a stnd Alpha into an SS they are their own animal ( I could be wrong though)........my very knowagable drive guy said Merc did offer a hardened upper gearset fothem but now the new ones have all been brought up to that spec.......you can have aftermarket nosecones installed and a Simrek drive shower is definatly a high performance modification......they run hot!!!! ........change drive oil often and watch the level.....if it gets even a little bit down you are in trouble