Rebuild Mercruiser 165 or buy Mercruiser 4.3L

[mastergat]

Hi, I was going with the idea of rebuilding the original 165 in my Flamingo but my local boat mechanic told me it would cost more than buying a 4.3L.

What do you guys think I should do? I get so many opinions and I would like to make the best decision.

Thank you!

 

[nola mike]

4 or 6 cyl?

 

[mastergat]

4 or 6 cyl?

It's a 6 cyl

 

[biggjimm]

I'm assuming (which I know I shouldn't do, ha) you're talking about going from an inline 6 to a V6? If not then never mind but If so you'll have the added expense of whatever accessories you'll need like exhaust manifolds & risers & whatever brackets & pulleys you'll need & if you're getting a new long block 4.3 you'll need intake manifold & carb, water pump, distributor, possibly a starter (yours may work??), flywheel is probably different, harmonic balancer & motor mounts & ??? The 4.3 V6 would be a nice upgrade if getting everything you need to swap it is do-able. Performance wise, most of them are comparable to small V8's. They are basically a small block Chevy with two cylinders lopped off so it's no surprise that they would perform well. Of course my experience with them has mainly been fuel injected vortec trucks but they are plenty powerful. Good luck & keep your project posted however you decide to proceed. Jim.

 

[Bondo]

Ayuh,...... Welcome Aboard,.... Basically, What big jim said,.....

The only practical way is buy a donor boat, with the motor ya want in it, to get all the tiny expensive swap parts,...

 

[Scott Danforth]

That's a hard one. I would probably rebuild the existing inline as I have a soft spot for inlinners The 250 inline runs about $1200-$1500 for a rebuild at many machine shops.

 

[Fishermark]

I too like the inline engines - especially the 250. In addition to what the others have said, the front mounts are different as well. So you would need to fiberglass in new pads for the mounts to bolt to. Lot of work for not much gain. Rebuild or find a good used straight six.

 

[mastergat]

Thanks for the replies guys! I'm in Canada by the way (dunno if the price for rebuilts are the same as in the US)

I was told that the rebuild of a 165 inline 6 would cost me way over $2000 so that's why I thought of buying a 4.3L, also it's cheaper on fuel.

 

[achris]

I went through that same exercise in 1994. Rebuild (an aging in-line 6) or fit a brand new 4.3... Went the 4.3 route, and don't regret it for a second. Yes, the old 250 is a nice engine, but the 4.3 is way more powerful, better on fuel and much quieter. I had a lot of hull work to do, but it's worth it. I had to widen the engine cover, open out the floor at the sides to accommodate the new mountings, and slightly modify the transom cut-out. Would do it again, and recommend it to anybody consider it.... As Bondo suggests, get an old boat with a 4.3 in it and transplant the lot. I'd even look at a freeze damaged engine you could get for a steal. Plenty of base blocks available in truck wreckers

Chris.......

 

[mastergat]

Well, I just got back from my mechanics, a 4.3L can't fit in my Flamingo ! I have no choice but to go the rebuild way!

 

[Bondo]

Ayuh,.... My guess is, yer mechanic don't do glass work,....

 

[Scott Danforth]

you may want to check the classifieds on inliners. http://inliners.org/

 

[biggjimm]

Ayuh,.... My guess is, yer mechanic don't do glass work,....

There's a difference in "it won't fit" & "I don't know how or don't want to do the work to make it fit" Thats the beauty of fiberglass & wood construction, you can pretty much do what ever you dream up. It might not be "easy" or "quick" but it can be done.

 

[HT32BSX115]

The 250 L-6 is probably one of the BEST, smoothest running engines ever installed in a boat. "Long-Blocking" [rebuilding] one shouldn't cost all that much but if I'm not mistaken, the manifold and riser are getting more expensive these days..........


The 4.3L V-6 would require side engine mounts (read: a little fiberglass work) PLUS, maybe your engine compartment is a tad narrow [read: a little more fiberglass work]..........

You would also need a slightly different drive ratio, since the WOT rated RPM for the 4.3 is a bit higher than a 250 L-6. (maybe a little more than a "bit" higher)

If you could find a rotten boat with a COMPLETE newer (Alpha Gen II ) 4.3L engine + drive, it would be absolutely worth the swap. But understand you would need to do some engine compartment "stuff" to make it all fit properly AND it would be more money over just rebuilding your 250 and bolting it back in...........depending of course, on how cheaply you could buy the "donor" boat.

It would be a worthwhile project if you wanted to do a winter project. If you have to pay someone to do it, you might just be better off just getting the 250 rebuilt and bolted back in. (Don't forget to replace the manifold, riser and coupler while you have the engine out.)

Cheers,


Rick

 

[achris]

....You would also need a slightly different drive ratio, since the WOT rated RPM for the 4.3 is a bit higher than a 250 L-6. (maybe a little more than a "bit" higher)....

Nope, can use the same drive. WOT on the 250 is 3900-4300. On the 4.3 (4 bbl) is 4400-4800... The 250 has a 1.65:1 drive ratio, and my new 43.MPI came with a ......1.62:1 drive.... Earlier 43.s were supplied with 1.84:1, but they moved back to 1.62 about 10 or so years ago.

Chris.....

 

[HT32BSX115]

Nope, can use the same drive. WOT on the 250 is 3900-4300. On the 4.3 (4 bbl) is 4400-4800... The 250 has a 1.65:1 drive ratio, and my new 43.MPI came with a ......1.62:1 drive.... Earlier 43.s were supplied with 1.84:1, but they moved back to 1.62 about 10 or so years ago.

Chris

Well, there you go then....And they're all reverse rotation down there in OZ aren't they?

 

[achris]

...And they're all reverse rotation down there in OZ aren't they?

Yes. And we put the prop on the front of the boat, and I have to write this upside down so you can read it.....

Chris