305 cu in Performance Options WHICH

"We have a 1987 Bayliner Cierr

"We have a 1987 Bayliner Cierra 2550 with the 305 Chevrolet engine. Being remarkably underpowered I am looking at the more effective methods of reliably increasing speed of this boat. With 2 adults and 1/2 tank of fuel, we may top 22 knots near 4200rpm. IN THE LONG RUN, is it better to swap engines, maybe the drive unit as well or can some other performance mods pay off with a little less work."

"Assuming your 305 already has

"Assuming your 305 already has a 4 BBL carb, swapping in a 350 long block would net you another 30HP, and would be the low budget option.
You can get a 350 crate engine (called a 290HP) from GM, swap the core plugs to brass and put in a marine camshaft. It's called a 290, but at the 4200-4800 rpm range, it makes 260, which is 30HP more than a 305 4 BBL.
If you have a higher budget, a 383 stroker would help immensely to bring top speed up, but the Cobra drive would be working slightly above it's maximum HP rating.

1987 is the transition year for Chevrolet small block V8's from 2 pc rear main seal to the newer 1 pc rear main.
Do you happen to know which design your 305's rear main seal is?"

"This block has the 1 piece se

"This block has the 1 piece seal.. I do think the drive would be operating beyond its capacity as you said and that part is what starts to make me draw the line on whether or not to spend $$$ on a swap of so many components VERSUS the option of finding another boat in todays market. We paid $4000 for this boat 4 years ago and it has been worth 4X that in its fun, reliability and flexibilty of use. Cosmetically it is exceptionally clean and EVERYTHING works. I replaced the entire instrument panel with new gauges and we put on a new camper style top. I COULD NOT ASK for more out of it EXCEPT....speed.

In my motorcycling days a stroker did produce power. But the trade off in reliabilty stunk! Spending that much more on a 383 and drive train probably makes little sense. Do you think that 30HP can get 4 people and a full tank on plane in less than 2 minutes ? I can swap this myself so I am not concerned with labor but eventually, it gets to that magic $$$ point.

Honestly, with 4 adults she REALLY bogs down. In the wrong bay conditions, we barely make 15 knots. Our current prop went from 15 1/2 x 15 to a 13 x 14 Mirage SS. Makes a bit more lift to plane the boat since it does not bite the water as much.
I do appreciate this exchange of information..!"

"I think driving that boat wou

"I think driving that boat would be a completely different experience with a 383.
I had a very similar 10 foot beam boat (Cruisers 266 Veesport) with a single 454 rated @ 330HP.
It was not speedy, topped out at about 32 mph, but JUMPED on plane. If you have trim tabs and with that 2550's wide beam, planing would be very decent with a stroker.

There are always people who are in no particular hurry that you could sell that boat to.

You would have to respend your purchase price in parts to get a 383 in the boat. Not decisions anyone can really help you with.
Selling and buying no fun.

Here's your 383 part:
http://www.jegs.com/p/GM+Performance/1151134/10002/-1"

"You know, it's not like I

"You know, it's not like I'd want to be a speed demon like those Cigarettes I see all over the place. It's just that at 15-16 knots when the throttle is almost full, you would like to just get it going another 5 or so knots so it LOOKS like you are getting somewhere ! I like this boat, it also has new upholstery etc. etc. Looks like it is destined to chug along...Thanks HyStat"

"Ayuh,...

I think, that You

"Ayuh,...

I think, that You'd think, that you had a Brand New Boat,...
If you drop in a 350, with Vortec Heads,+ a 4bbl. Carb....
That could easily net you about 280hp... Possibly more..."

"In looking around the area fo

"In looking around the area for an engine /driveline combination, I found several 350 cu.in. 5.7 efi bravo 1 and bravo 2 setups where the boat was repowered. Would this be a straightforward swap or do I need to be concerned about the physical cut out dimensions of the old cobra drive currently in place. I know the 305 to 350 block should be a simple drop in....
Thanks AL"

"[b]" Would this be a stra

"" Would this be a straightforward swap or do I need to be concerned about the physical cut out dimensions of the old cobra drive currently in place."

Ayuh,....

You'll have to drill 2 more holes....
And possibley alittle tuning with a diegrinder...."