DuoProp Gear Ratio and Small Block V8’s

[LegacyT]

I’m looking into options for upgrading from my original 305 AQ231A. I’m considering a 383 or maybe a tuned 350. I’d like a 383 but a new crate 350 is also quite a bit cheaper. But regardless, AQ DP lowers are available in 1.95 and 1.78 ratios. I know the 1.95 was made for the small block 305’s and 350’s and the 1.78 for the big block 451’s and 500’s. If I chose a high performance 350 or 383 which ratio should I be looking for since power is starting to reach big block territory?

 

[Scott Danforth]

stick with the drive / ratio you have. I went BBC and kept the 1.95:1 ratio on the 290DP. its literally one prop-set away

for example.....I still use the B6 props I was spinning with the warmed over 350 for water sports, I have a set of B8's which are a bit too aggressive until I change the carb to a 850DP from the current 715. so right now, looking for a B7 set.

your currently spinning B4's or B5's. you may end up with B6's going to a 350 or a 383

 

[QBhoy]

I’d say there are plenty you could do with just props. Pretty sure you wouldn’t need to go higher ratio. Just FYI...these came with 4.3. Powering them too. Some 4.3 were almost as powerful as the 305ci too. Like the AQ205 I had. My 23ft heavy U.K. built 4 berth pocket cruiser had a aq205 turning B5 props to dead on 4800 rpm and mid 30’s. There a few levels of props to go above that and the c series stainless versions would lower rpm too. But those aren’t cheap at all. Of course they have all now been replaced by j series and something else which I can’t quite think of. Been a whole since I had a VP. Back to Mercruiser and merc V6 smoker...and recently a 4 stroke merc too. Love the VP drives and their brilliant engineering...but it true that I could buy a new alpha for the cost of repairing an old VP.