4.3L variations on HP

[ggundersen3]

Im looking to upgrade from a 120HP Force/Mercury OB on my present boat to a 4.3L V6 IO on the next boat. I've had 3.0L 4 Cyl and 5.0L V8 on older boats but never a 4.3L. I've been looking. What are all the different variations on HP on the 4.3L? I see them as low as 165HP up to 210HP, some 2 barrel carb, some 4 barrel and some EFI. Explain what I should look for and what I should avoid. The newer the boat the higher the HP? Explain. Thanks!

 

[Rick Stephens]

All the 4.3L's I have seen are either 190 or 205/210 at the prop. The 2 Bbl at the low end and the 4 Bbl at the top. I have never been around an EFI model. They get up to 220 from what I have seen. EFI is a bit spendier to build and less likely to need routine maintenance. Of course with EFI, when you feed it dirty fuel it is more apt to cause more difficult issues to repair. All in all, I don't think it matters which you get as long as the horsepower is appropriate to the boat. The 4.3 is a really nice motor. There were a number of major modifications over the years, main one being Vortec heads in 1996.. Balance shaft came out in '92. Often times, Mercruisers was a year behind the Chevy factory as they used up inventory, so you usually see '97 before the Vortec heads came out and '93 for the balance shaft. The balance shaft uses about 15HP. Without the balance shaft the V6 needed fluid motor mounts.

 

[ggundersen3]

Thanks Rick. I saw a '95 yesterday and dealer said it was 165HP. Then I looked at a '93 that the owner said was a 4.3LX and was 205 HP. Just wonder what raises the HP so much.

 

[Scott Danforth]

4 barrel intake and cam change

the 4.3 went from 155 hp (crank) in 1985 to 220 hp (prop) in various carb/efi models

here is some reading on the 4.3 http://forums.iboats.com/forum/engi...history-of-the-4-3-liter-with-casting-numbers


I would suggest looking 96 or newer with the 4.3 and get the best of everything.

 

[ggundersen3]

Thanks. Very helpful.

 

[ggundersen3]

How many hours are just too many hours no matter how well the engine and drive were maintained? Somebody said to me once time that around 800 hrs is the maximum.
I'm looking at a '93 20' Sea Ray bowrider with a 205HP 4.3L. Clean, immaculate, really well maintained all original boat but....hour meter is showing 1100 hours! Way way too many right?

 

[Scott Danforth]

Rebuild at about 3500 hours if it has been maintained. 1100 hours is like 30,000 miles on a car

 

[Bondo]

Ayuh,.... I've got a '94ish 4.3LX, that started as a Fresh motor in '99 when I did a 3.0l swap to this 4.3LX,....
It's the 205 hp, with the Merc/ Weber 4bbl,....
I've got the Vortec heads in the garage, just never got 'round to that swap yet,...

It's got something over 2,000 hours on it now, 'n last compression test said it's still in A1 condition at mid-140s to 150 psi all 'round,...

The Charter Captains 'round here generally shoot for 2,000/ 3,000 hours outa their BBCs before rebuild or replacement,...
It depends on how badly they're abused,...
Hot Rod Cigarette boats are generally Lucky to see 500 hours,..

 

[Rick Stephens]

How many hours are just too many hours no matter how well the engine and drive were maintained? Somebody said to me once time that around 800 hrs is the maximum.
I'm looking at a '93 20' Sea Ray bowrider with a 205HP 4.3L. Clean, immaculate, really well maintained all original boat but....hour meter is showing 1100 hours! Way way too many right?

Do a compression check on it. If it looks good, the number of hours is fairly meaningless.

 

[QBhoy]

In the last 20 years and generally they came in;

175hp 2 barrel carb
190hp 4 barrel carb
205 4 barrel carb and vortec heads
210hp and efi single point injection
220hp and MPI multi point injection

At least here in the uk, that's the usual guises
Great engines.

 

[Scott06]

Immaculately maintained is the key words. Wouldn't worry about the hours check compression (135-150 psi) and oil pressure (10 lbs per 1000 rpm hot), if it's priced right go for it.

 

[bspeth]

Guys,didnt some of the 4.3s have them bat wing manifolds on them? I think I read on here to avoid those.

 

[Lou C]

Both OMC and Merc used the one piece bat wings in certain years. I had the OMC bats on mine for 15 years of salt water use and never had a problem with them but I ran each set only 5/6 seasons in the salt pond. Merc and also Barr Marine made conversion kits to convert these to a 2 piece system. I converted mine to a center riser Volvo style exhaust (Barr) during my top end overhaul.