Reproping 1989 Sea Ray 340 - shaft drives

[boatman4520]

I own a 1989 Sea Ray 340 now kept at a resivoir in Pueblo Colorado. I probably know less about this boat than any other I have owned. The boat runs well but will not plane. It was first kept and I assume outfitted for a low altitude lake in Texas so I am assuming the props need to be changed. But with shafts I am unfamiliar with the prop pitch or size. I have also heard that with shaft drives the gears can also be changed. Anyone out there familiar with prop or gear outfitting would be helpful.

 

[KayKook]

The boat came stock with 17" x 17p 3 blade 1.25" shaft. You can probably figure out from there. Your post says 1989, but your info says 1988. The info I gave is for a 1989 340DA.

 

[dpmulvey]

That is a lot of boat for a pair of 350's. Are you reaching the MFG WOT range?

 

[hottoddie]

You need to clarify what engines you have. Are the engines 350 cubic inch or 350 horsepower? If they are 350 cubic inch then the boat is under powered and will struggle to get on plane. how long have you owned the boat? Was this a problem when you bought it? If the engines and gears are original to the boat then maybe they need to be tuned for a higher altitude but that's beyond my expertise.

 

[ron tremeer]

1989 340 have 454 or diesel engines

 

[NorCal Boater]

You also don't say if it is a DA or DB. Makes a difference. My 1989 340DA had 340hp 454's. The props on the boat when I bought were 16 x 16. One engine runs in reverse but I cannot remember which. Starboard I think.

At sea level the boat got over the step at about 22 MPH and would stay on plane to about 1800 RPMs/20 MPH if lightly loaded. At WOT she would turn 4400 RPMs and reach 30-32 MPH depending on the load. You've got a problem.

I would start by completely tuning the engines if it has not been done in a while. And that means plugs, cap, wires, timing, fuel filters, etc. Make sure the spark arrestor is clean as well as the bottom of the boat. You need to do this before you start spending money on props. I think you can re-jet the carbs for the altitude. A local mechanic should be able to advise you on this.

Remember, if you have the DA(Sundancer)this boat is a$$-heavy and does not get up on plane easily. The best method is with the tabs full down, punch it to get it over the step and then back off the throttles to a comfortable cruise. I crused at about 2800-2950 RPMs and 22-25 MPH again, depending on the load.

Good luck and keep us posted.

Shawn

 

[Saverio]

Are you using ur trim tabs. My 31 and 39 won't plane without using full trim. You need the tabs to bring the now down. While at the slip with a partner have him hit the trim tab rocker switches and look at the stern u will see the tabs in the water they should go up or down if they don't check breaker or fluid in reservoir

good luck
Saverio

 

[Lugnutz]

I would start with a compression test on both engines first regardless of what engines they turn out to be. If the inside of the engines are not doing what they are suppose to be doing you will have alot of wasted time and money spent on other things that won't make any difference. Just my .02 worth.

 

[jitts3]

The fast way for a novice engine guy to tell the difference between the 454 and the 350 CID Chevy engines is the center two exhaust ports where the head meets the exhaust manifolds. The 350 CID has siameased exhaust ports for center two. The 454 CID has separated exhaust ports. Kinda like this

oxoxoxo.......454
oxxooxxo......350

o being the exhaust ports.

I don't have a photo available of a 454. This is a photo of a 350 that came out of my 78. The exhaust manifolds are removed. Now you can see that port pattern.
Hope that helps

 

[Lugnutz]

Or a quicker way if the manifolds are still on, the 454 valve covers are wider than the 350 engines. I think the 454's are almost 7" wide and the 350's were roughly just under 5" wide at the bolt holes.