1982 Bayliner 1950 capri top speed with 4.3

[Jim P.]

I bought a 1982 Bayliner capri about a week and half ago that had a 3.8 volvo with a cracked block for 600.00. Somebody didn't winterize it properly and it froze and broke. I bought a 4.3 from a 98 s10 pickup and rebuilt this to put in the boat. I used the old 3.8 heads, intake and carburetor. We also had to replace the bearings and seals in the bell housing and also the raw water impeller. We got it to the lake today and it runs like a swiss watch. we took it easy for a while to break it in a little but we did open it up a couple times but it will only do about 40 mph with about 900 lbs people in it. I figure it would do a little better. It runs about 4600 rpm wide open. It jumps up on plain very easy. It has planer boards on the transom. Would it go faster without these. Another thing is it seems to be hard to keep going straight when idling slow. You have to keep turning the wheel back and forth to keep it straight. It is fine when you open it up

 

[Sparkinator]

What pitch prop are you running? If it's a smaller pitch, 40 mph sounds about right.

Have you weighed your boat? A lot of the older ski boats, are notorious for soaking up water like a sponge. They didn't have nearly the build quality that manufacturers have today, and lots of older boats end up with water-logged foam insulation.

As far as the steering at idle speed, I think they all do that. I know mine does.

I'm not sure about those planer board. I assume you are talking about trim tabs. Can you post some pics?

 

[Jim P.]

The prop is a 14 x 17. I have had a couple other boats but this one extremely hard to keep on course at idle. The wheel will turn almost a half a turn before it effects the boat. It is possible that the boat is water soaked as it has sat outside for about a year with a cover but the cover does seem to leak. We are going to try and waterproof it. It there a way to dry the boats out after this happens?

 

[83Evinrude]

Another thing is it seems to be hard to keep going straight when idling slow. You have to keep turning the wheel back and forth to keep it straight.

This is called Low Speed Wander and its very common among v-hull boats.
Mine had quite a bit of it but installing smart tabs has fixed that, do a search on iboats and you'll find them.

 

[MikDee]

A couple of items, if you just rebuilt it, give it time to break in, & get faster. Next, is this a 2bbl, or 4bbl motor? I wouldn't expect much more of a 2bbl. One more thing, are you fully trimmed out with the drive at WOT? Also, if you have too much weight in the bow, the boats gonna wander more steering? What's your WOT rpm, and prop pitch?

 

[Jim P.]

The prop is a 14 x 17 and the wide open throttle was 4600 rpms. It has a 2bbl. carb. The boat doesnt have power trim and I havent tried moving the pin to a different trim setting yet.

 

[500dollar744ti]

Whats your WOT range? Adjusting the trim should give you more top speed but it will also raise your engine rpm a little, as long as you trim up and the rpm is still in the acceptable area it will be good.

 

[MikDee]

Why did you use the 3.8 heads? Aren't the valves on those smaller then the 4.3 heads? You'll probably pick up more speed as the engine, & bearings wear in, I'd guess 45mph would be about it, without power trim, or a 4bbl carb. Oh, make sure your outdrive is always at least parallel with the bottom to start with, to keep your bow up, if it were to get too low, the boat's bow could dig in affecting your steering.

 

[doyall]

... about 900 lbs people in it. ...

That's a lot of weight. How many ice chests? What other provisions/gear? Ditch everybody but you and everything not safety related. Only then will you get a good top end indication. Oh, and don't rely on the on-board speedo - use GPS if you want an accurate reading.

 

[Jim P.]

I used the 3.8 heads because I didnt have an intake that would work with the vortec heads and a carburetor. I was also told that the exhaust manifolds would hit the valve covers of the 4.3 but I don't know if that is accurate or not. There seems to be plenty of clearance now. I was using a gps for the speed.

 

[jestor68]

The on line 1982 Bayliner 1950 owner manual lists a 15 X 17 prop as standard and suggests tilt pin hole # 2 as the trim setting for the out drive.

I believe 4800 rpm is the max rpm for that motor; so 4600 rpm with that load on board sounds good.

I suspect that it would gain close to the max rpm with less people/gear in the boat.

It should be noted that the early VP drives were not known for high speeds; so doing 40 mph with that load is actually OK.