I agree a 1:50 would improve all around.

Is the gear reduction in the upper or lower?

If i go to a 1.50, everything after the gear reduction will see that much more stress. They put 1.36's behind the 502's for a reason, i figure. That's their band-aid for weak components, if i take off the band-aid it might start bleedng.

The 27 in my shop has a
1:50
502
23p
jumps out the water and runs good, not sure of rpm or speed ?

The new XR's change it in the lower I believe.

Higher gear ratio is better on the drive due to less torque load, you may also see a speed increase.

I did the IMCO thing last year, had the same results.

That would be the approximate equivalent of running a 20.8" prop on my boat. I'm running a 21" Mirage +. I highly doubt the hydrodynamics are so wildly different between a 21" and a 23" prop (of the same type, of course) that i would see significantly different results by going to a 1.5 ratio and a 23" prop.

That said, there's definitely room for improvement in my setup, and i don't believe a Mirage + is necessarily the right prop for my boat. But i think the only thing i'll gain by going to a different ratio (i'm not, by the way, i'm cheap) is a better selection of props, and i think it will put more stress on certain (expensive) outdrive components. Definitely more stress on everything after the gear reduction.

What does the boat you're referring to have for torque? Is it a stock 502? (mine's a stock 502 mag, carbed).

What kind of prop is it running?

What's your idea of "jumping out of the water"? What kind of load? What kind of tabs, and how much are they used?

is it a step hull? Mine's a 1991, non-step.

What does it top out at? I'm getting 61-62 mph, might have another 1 or 2 in it if i get out there by myself on low fuel.

I'm not trying to be a dick here, i'm serious, i'd like to know more about the setup on that boat and how it performs.

I can get my boat to "jump" out of the water if it's just me and a friend, with a reasonable fuel load (less than full, more than half), and i put the drive and the tabs all the way down. Sometimes i like to slow down for a second though, just to grab something that fell off the dash or something, then get right back up on plane. Putting the tabs down to get on plane is easy, but it's a pain in the rear to pull them back up, adjust the drive, steer, and adjust the throttle all at once when the boat comes on plane. Given the cost of outdrive repairs, though, i think i'm just going to make sure the tabs are all the way down every time i get on plane, to minimize stress on the drive. In the same light load conditions, i can get it on plane at just over 1/2 throttle with all the tab and the drive all the way down. With a full load on board, it's a different story, though.

With 4 people on board, completely full fuel (filled it to weigh the boat / trailer setup) and a tool box in the cabin, not taking the time to put the tabs all the way down (leaving them at a good cruise setting, puts the tips below the hull at least a couple inches), it takes a lot more to get on plane.

You should only go to a 1:36 unless you run out of prop i.e. 34pitch. I would say 90% of bravo BBC configurations are 1:50. Did you just get the boat? Maybe the previous owner had big power in the boat, therefore the need for the 1:36.

It's not my boat but I can find out some details, I know it's stock

Clymers manual says in 1991, they put 1.36 drives behind 502's and 1.50 drives behind 454's. Best i can tell, it's a stock 15 year old drive.

A previous owner did have a blower motor in there, though. I couldn't tell you if this was the drive it was attached to or not.

I called merc and ran the serial numbers before i bought the boat. Drive and transom housing are 1991 vintage. Block was originally a 1994 MPI motor.

Your drive in a 27 ft fountain should last at least 300-400 hours behind a stock 502. I ran 625-675 hp in a similar weight boat for over 125 hours before shearing floor out of stock bravo upper gears and I was running a 26 pitch 4 blade prop w/ 1.50 gear ratio. Drive broke the first ride out after going to a 28 pitch 4 blade and some other improvements. Was your coupler aluminum or steel splined? You probably already been told this but if not insist on the xr type coupler with longer snout on it,they support the shaft real nice and last ,Smitty

thats the same thing I was thinking,had biger power