Replace engine and outdrive or just outdrive?

[jpstude]

I am looking at a mid-70's 18' fiberform with a 165 Mercruiser in it. The engine is toast but, the owner said the outdrive is fine. Should I just get another 250 six or, upgrade to an Alpha one and a 350? Any ideas on what this boat with the 165 would cruise at? She's for fishing not waterskiing but I want to be able to outrun the weather. On the tech side of the question: would I have to replace the transom if I put in an Alpha one or, will it fit with some modification of the old hole for the 165?

 

[Bondo]

Re: Replace engine and outdrive or just outdrive?

On the tech side of the question: would I have to replace the transom if I put in an Alpha one or, will it fit with some modification of the old hole for the 165?

Ayuh,.. If any modifications are necessary, it'll be minor,..
Redrilling a hole or 2,.. diegrinding alittle clearance or whatnots...
I'd sooner think you'll find wood Rot,+ have to rebuild the whole hull due to it's age...

You'll have to decide if you want 165hp, or 265hp,.... though a V8 in an 18' hull is abit much...
A 4.3l/ Alpha might be a Nice package...
She'll probably Cruise in the 25/30mph range,... Maybe alittle less, I doubt any More...

Welcome Aboard,...

 

[mkast]

Re: Replace engine and outdrive or just outdrive?

How much money do you plan on spending on this project?

 

[jpstude]

Re: Replace engine and outdrive or just outdrive?

She's glass, appears to be sound and the transom seems to be OK. If I have to replace the transom, I've done that before so, I can do that myself. I think you're right, on the 350 V8. I'm not trying to set a speed record, just get to the fish and home again. 20 to 30 mph would be fine. I am on a fixed income so, I'm trying to do this "on the cheap" but, it takes what it takes. Safety first. I'll check out a 4.3L and see what they run. Thanks for the welcome and the info. I'll be picking your brains from time to time. I'd rather have the knowledge from those that know than do the job more than once. Oh, she'll be all over Puget Sound, loads of lakes, and even some fishing on the Skagit River. J.P.

 

[ziggy]

Re: Replace engine and outdrive or just outdrive?

the 165 should be fine imho. i like mine anyways. it's a good torquey engine. i've out run the weather with mine and had to deal with it too. works just fine. max speed for my 19'er w/165hp is 42mph, gps. had me a 72 trihull with a 165 too. it did 40ish per speedo, not gps.

if your on a budget, going to something other than whats there seems like it'd be more expensive. it's expensive enough trying to maintain a boat in good condition w/o trying to make it something it's not.

i just did a shade of looking on line about fiberform recently. there's a pretty limegreen cabin cruiser on my lake that i thought was cool, so i looked around online. anyways. to sum up what i read was they were heavy boats. they also, like everything else, have wood rot issues. bayliner bought them.

ya may also want to consider the max hp rating of the boat in question. if you go over, the dnr man may not like you if he catches on.

 

[PiratePast40]

Re: Replace engine and outdrive or just outdrive?

I have a 76' Fiberform I/O runabout with closed bow. Best I can tell, it was the Monteray model. I've gutted and rebuilt the interior so I'm not hauling around waterlogged foam and extra water. Mine has a 130 hp volvo 4 cylinder. With the current 14" x 15 pitch prop, it maxes out at 27 mph at 5100 pm. It's underpropped and can get to 5800 rpm and 29 mph if I'm not paying attention. What I'm saying is that at the estimated weight of around 2400 lbs with fuel, gear, and a couple of fat guys, it'll do 27 mph with 130 hp. And that's with being underpropped. It's certainly not a speed demon but that gives you an idea what it does at that hp, prop, and estimated weight.

I have a 17 pitch prop that I'll try as soon as the snow melts enough to fill up the reservoirs in the spring. Ziggy, I'm pretty sure that max hp rating for a hull only applies to outboards - at least as far as the law is concerned. Common sense, weight distribution, and your wallet may be a better ways to determine max hp for an I/O

 

[Fishermark]

Re: Replace engine and outdrive or just outdrive?

The engine is toast but, the owner said the outdrive is fine. Should I just get another 250 six ...?

I recommend getting another 250 straight six. They are great engines.

Better yet, simply rebuild, or have rebuilt, the engine that's in the boat. When the owner says the engine is "toast" - it could be as simple as it hasn't been run and won't start due to needing a tune up... or it could have a rod sticking out of the side of the block.

Bottom line, find out what's wrong with the engine before buying a replacement.

If you do buy a replacement, you need to be aware that the block used for marine engines has an extra area cast around the front timing gear area for the front mount.

One more thing - even though the owner says the outdrive is fine... it would be worth a check of that as well.

 

[jpstude]

Re: Replace engine and outdrive or just outdrive?

Man, you are a great bunch of guys! As a result of your input, I'm going to stay with the 165, see if is OK, and if not, see if it can be rebuilt. Thanks for the tip on the "wet foam", I'll be checking that very carefully and getting rid of it if it's wet. I don't see any on the hull, is the foam under the floor? No sense in hauling that kind of weight around. Additionally, thanks for the heads up on the marine vs landlubber blocks on the 250's, that makes me much more inclined to see if the old one can be fixed. I'll have the outdrive checked to make sure it's OK, I really don't feel like rowing too much at my age LOL. Oh, yeah, she's a closed bow model. Thanks so much for your advice and input. I'll have more questions as I go, I'm sure, and I'll keep you updated on progress. J.P.

 

[ziggy]

Re: Replace engine and outdrive or just outdrive?

sounds like ya got a good plan to me. ya'll probably like the engine. can't say i've ever heard of anyone that don't.

i do stand corrected and PiratePast40 appears to be correct about the engine size for i/o's.. http://www.boatus.org/onlinecourse/ReviewPages/BoatUSF/Project/info1a.htm

yes the foam is under the floor..

mines closed bow too. guess it's not desirable these days as boats don't come that way much anymore. don't know why though, i sure like mine....

 

[fuzzybob]

Re: Replace engine and outdrive or just outdrive?

jpstude, welcome to iboats... you may want to go to the top of the forum page and click on the "Adults Only" sticky. You'll find a ton of great info on all kinds of boating questions plus you can download the factory OEM manual for your engine and outdrive. All for FREE thanks to dons and other forum members!!! Good luck on your project.

 

[jpstude]

Re: Replace engine and outdrive or just outdrive?

Does a 165 Merc have a seperate heat exchanger? Or, does it just pump enough water to keep it cool?

 

[Fishermark]

Re: Replace engine and outdrive or just outdrive?

You will have to look and see... but I suspect it does not.

 

[jpstude]

Re: Replace engine and outdrive or just outdrive?

Thanks for the info. This boat doesn't have the engine with it so, just the head and 165 outdrive is there. After alittle research, it appears you could get them with or without the heat exchanger. They must pump enough water to keep them cool, although the owner said he broke the block on the old one... maybe a shot impeller or water pump. Well, on to finding another 250 cu. marine block.

 

[jpstude]

Re: Replace engine and outdrive or just outdrive?

Update - found whole running 165 hp. Has everything I need! I think $400 was a great price. It will sure make the job a lot easier, and shorter. NEXT - my 21' SeaRay CC. Repower with 454- Yahoo! Tanksguys.I'll be back with more questions.