Lower unit question

Ratio is set in the upper end. Lower end should be a general swap. the 1.5:1 is the baseline for the B1 + 7.4/454

My Chaparral 2550 had a 1.5:1 Bravo1 with the 19" S/S prop and was a rocket on top end.

Ratios don't get crazy till the B3 is in the mix. My B3 is a 2.0:1 with 28" pitch props

 

With a boat your size, I would be strongly considering going to a B2 or B3 if replacing the lower. It is my understanding that they are all interchangeable. You may lose a knot or 2 at wot, if that is even a thing for you, but the low speed maneuverability and hole shot gain is day to night.

 

Steve,
I JUST went through tis. 91 same boat, motor, drive. Needed a prop seal. Was too corroded to remove the seal. B1 Merc lower is expensive. B2/3 even more. My mechanic recommended SEI. I asked around a lot (thread on here somewhere).
for a new lower with 3 year no fault warranty it was 1250 for lower, plus tax and shipping. Mechanic charged 500 labor. So for a little under 2k, i am good to go. Highly recommend this route.
See General Discussion, page 6, SEI outdrives.

 

Missed the part you already got something, good luck.

 

@Pirate Lady