bertram31.com

Good evening guys,
I have a 1983 B26 with Inboard Vortec 4.3s. I am looking to replace them with 350s. I know many have been converted. I was curious about real world performance numbers. Also looking for prop recommendations with the 350s and 1.5 to 1 boxes. Thanks in advance!

Flexxman:

I see there has been no responses and I am not sure this will help you:

- The B28 I have runs the 350's and I believe the weight of the B28 is almost double the weight of the 26?
- standard cruise is about 20 knots at 3000 rpm's for the B28's in this config, so you can obviously assume a significant performance increase given the size and weight differential
- Fuel burn at 3000 is about 20 gph combined
- 350 engines and blocks are readily available and affordable
- unsure of how the size might impact accessibility
- I can look but I think I am running 18X18's on my B28 currently and have an extra set you could try if the shafts are the same size but I can't imagine given the weight they would be the right application.

Good luck.

Mark

Thanks for the reply and the information. I am hoping to get 23-25 knot cruise @ 3000...I don’t know if I am being to hopeful or am about in the ball park.
Matt

My 25 runs approx that with a single 383 mercruser.

Matt I sea trailed a B26 with two 50 hr carbureted Crusader Classic 5.7s last July in NJ. I didn’t buy the boat but recall that 3000 rpm got about 20.5 knots and it took about 3200 revs to get to 22.5-23 knots. 4000 rpm got the boat to 30 kts. The shafts were 1 1/8” . Props might be noted in the survey I had done.

Question: what are the performance numbers for your 4.3s? For the boat I did buy, I’m looking at repower

As I look at choices, I’m thinking about budget. Going to 5.7 means new shafts, stuffing boxes, props, cutlass bearings, Upsize to 4” exhaust Including hose, elbows, exhaust logs, transom exhaust fitting. Maybe I should stay with V6s and replace with original Crusader 165s with modern EFI models. Maybe I can live with the performance... It sounds like you are not happy with it.

Back to the 5.7 idea, If I keep the same velvet drive trannies (rebuild them), the 5.7 motors would sit tight forward and may be hard to service from the front. If I changed to hurth, they seem shorter and would allow the motor to be more centrally mounted.

Chris,
The 4.3's numbers are not great. Obviously, or I wouldn't be considering a repower. I have Vortec 4.3's with 2 barrels approximately 190hp. I have new props on it which are ACME 4 blades, it is slightly over propped. I can only get about 4300 WOT.
Best I can recall below is the approximate performance with this set up. Normally get around 1 mpg no matter how I run it. The hull really wants to run at least 24 mph before the wake flattens out and runs efficiently.

3000 16 mph
3300 17.5 mph
3400 18.5 mph
4300 28 mph