Classic 18 Project, need guidance

[boatnut]

Well we have finally made a decision on how to proceed (at a high level, now need help). We have a beautiful '69 powered by a H&M 302/250 Volvo package. Boat is stock, original gelcoat, engine is original other than a few valve jobs. Drive is original other than a new lower seal and a u-joint rebuild.
After 36 years of running it still is a blast to run although speed is barely 50 due to a somewhat tired motor. We would probably nurse it along but your (appreciated) gas tank info has us worried -- no sign of leakage yet but the deck is coming off. We pondered the repower with a new Merc/Bravo package but have finally decided to stay with Ford/Volvo to keep the H&M heritage and to not have to rebuild the transom etc. We now need some consulting from you experts to help decide how to proceed and what to buy. I realize the value of your help and just made a donation to the registry to assist in keeping this great resource funded. We will provide experience as we get going (later this year) to the forum. Our questions at this time:

1) We have a 250 Volvo that works fine. Are there any advantages to moving to a 280 or 290 drive (other than trim which would be nice but I don't think is really needed on this boat, the most trimmed manual position on the 250 seems to work well).
2) Do the 280 and/or 290 drives have more prop options than the 250
(assuming they require different props which may not be the case??)?
3) If we change to a 280 or 290, I assume we need all the transom parts as well as the actual drive unit --- is that correct?
4) If we stay with the 250, I plan to have the unit completely gone through by someone to check gears/bearings etc. and have it blasted and properly repainted (needed), do you agree that this drive should be rebuilt?
5) In a past thread, some of you suggested going to a 351W (we would like to get over 300HP). Is there any difference from our current '69 302 truck block that H&M used as compared to a 351W regarding use of existing exh manifolds, crank mounted water pump, engine mounts, Volvo drive attachment etc.?
6) Another option is to buy a new Ford high performance 302 long block (I have seen some with aluminum heads although that might not be wise??). We are not at this time considering having the current block rebuilt as it has 36 years of aggressive marine use -- hard to believe it still runs so well. Any comments?

Your guidance on these strategic items will assist us in starting to gather what we need to start the project. Thanks in advance.

[txtaz]

Hi BoatNut,
I'm a fan of keeping things original. I can't help with the HM or Volvo part, but the restoration I can.
Remove everything. Test the stringers and transom for rot by digging into it (after removing the drive and engine) and looking for wet soft wood. It's most likely you will need to replace both. You can also tap along the transom with a hard object and see if the sound changes. A dull sound = not good.
If your going for a change, do it all at the same time. Some of the motor guys will chime in to help.
Have fun, It's a big project.
Wes

[Morgan's Cloud]

Ok, I'll start the ball rolling ... :biggrin: oops, maybe not .

The 250 280 and 290 Volvo drives are all great pieces of equipment (don't know too much about the 290) but you are aware that none of them have been in production for years ?

Are you proposing to replace your still working 250 unit with another 'older' unit ?

I don't think that the 280 or certainly the 290 will bolt onto your existing transom .

If you went with the newest of the lot and chose a complete 290 package the transom would have to be filled and re-cut.

[JimG]

Beautiful boat! Keep it original, the 250 is a great drive. Simplicity is what that boat is all about, just gas it and go!

[boatnut]

Beautiful boat! Keep it original, the 250 is a great drive. Simplicity is what that boat is all about, just gas it and go!

thks Jim, I notice that you have the setup we are considering (351w, H&M,
250), what speeds are you getting? On your just gas it comment, that has always been our philosophy on handling rough water with these boats -- just gas it and fly over it -- note the reminder label on the dash.

[JimG]

My boat will run 54.7mph (gps) on the last hole. I didn't like the way it handled, so I went back to the second hole, (my wife drives this boat a lot.) Second hole, 53.5mph. My 351w is very conservative, you can make a lot more hp with a modern cam, better exhaust, etc. I like the look of the old logs, so I kept them...

[gcarter]

if you went with closed cooling, you could go w/ any combination of heads and manifolds you chose. I'm sure your output would be higher w/ an operating temp of 180*-190*. The H.E. can be mounted low on the stringers and would still look very original.
I can't say enough good things about closed cooling. I love it.

[boatnut]

if you went with closed cooling, you could go w/ any combination of heads and manifolds you chose. I'm sure your output would be higher w/ an operating temp of 180*-190*. The H.E. can be mounted low on the stringers and would still look very original.
I can't say enough good things about closed cooling. I love it.

True George, we also boat (we live on a lake) in the winter and closed cooling also gives you the option of running a "bus heater" and blowing some
warm air from under the deck. It will be considered once I figure out what the basic drive and engine will be. thks, Ed

[olredalert]

Ed,

-------Any competent high performance marine engine builder can build you a nice 347 stroker motor out of your original motor. Most of these stroker combos can pull around 350hp without even breathing hard. Considering that you probably have less than 200hp now can you guess how much fun you will have? All that and your original 250 drive can handle the hp with no problemo after a simple re-fit! Its like having you cake and eating it too! You will still have yor original drivetrain but you will be having a ball. Only downside I can see is that it usually costs a bit more to rebuild your old motor than to just go out and by a stroker 347 crate motor from any of the dozens of engine builders out there...............Bill S

[boatnut]

Ed,

------- All that and your original 250 drive can handle the hp with no problemo after a simple re-fit! ...............Bill S

Hi Bill, are you indicating that the 250 (that we have) will need some sort
of refit before handling the HP? I asked a sterndrive rebuild company in Washington about using the 250 with 300-350HP and what it would cost for them to go thru the drive, change bearings any worn gears etc. and to bead blast and thoroughly paint the drive when it is apart. Here was their response:

"Only the 290 drive qualifies for that kind of horsepower...and would be a very expensive exercise to change over to. Suggest you stay with what you have and keep the horsepower at less than 260.
The average cost to custom rebuild an existing 250 is around $3500.00. Let us know how we can be of further assistance."
Wayne
www.sterndrive.com

They are likely being conservative on the HP rating --- but maybe 300HP is a better target if we use the 350? What do you think?

[JimG]

Are you having trouble with the drive?

[boatnut]

Are you having trouble with the drive?
No, none. The drive has some corrosion/paint issues and to me it looks like it should be taken apart to be painted properly (otherwise the corrosion will continue on the surfaces that mate each other). Once it comes apart it seemed logical to inspect it, change some bearings etc. ---- however I might be going overboard with this??? What do you think about their comment that the drive is limited to 260HP, I have heard a much different assessment from members of this forum.

[JimG]

I'd paint it, and forget about it. If it ain't broke... :biggrin:

My original 351W was factory rated at 290hp, so I wouldn't worry about bumping the HP a little. I guess if I were going to 400+, I'd worry about it a little, but you are most likely OK if you don't do a lot a full throttle air! Volvo's are very over-engineered drives.

[boatnut]

I'd paint it, and forget about it. If it ain't broke... :biggrin:

My original 351W was factory rated at 290hp, so I wouldn't worry about bumping the HP a little. I guess if I were going to 400+, I'd worry about it a little, but you are most likely OK if you don't do a lot a full throttle air! Volvo's are very over-engineered drives.

I hear you, I subscribe to the same religion usually so I will look into what I can do about painting with minimal dissassembly---the drive can always easily come off when and if it ever breaks. Do you know if the prop selection is more limited on a 250 as opposed to say a 280 or are they all the same??
I read that there is different prop shaft lengths etc. Also will the same H&M log manifolds that I have and the crank driven water pump etc. bolt onto a 351 the same as onto a 302? Of course staying with a 302 would be closer to original I guess??

[JimG]

The 250 is a "short-shaft" and the 280 a "long-shaft", I believe. No problem, just drill & tap the shaft andyou can use the long shaft props like an Ultra on your 250. I did it with no problem at all.

Everything should bolt on, no sweat. The only thing you cannot use is the intake manifold. Btw, the 302 has a better selection of killer intake manifolds than the 351. Check out this site http://www.jason.fletcher.net/tech/intakes/intakes.htm

I went with a Stealth.

[olredalert]

Ed,

------I would certainly pole us about our durability issues with horsepower and Volvo drives. However, the DONZI factory ran Chris-Craft 330 hp LT1 Chevy engines on 270s in 1971/72 era. It was a great package as it sounded good with those solid lifters and all. I, personally would not have a problem running 350hp thru a good 259 drive!!!!
------The only reason I mentioned going thru your 250 was because you said you were going to, and that way you have a base line with the new power. Your rebuilder may be worried about warranteeing his rebuild, but he isnt the only Volvo rebuilder out there. Im somewhat mechanically challenged and I took mine completely apart and re-gasketed and painted it. Biggest problem was finding the right shade of Volvo grey.
------In regard to the intake, if you stick with a 289/302 stroked motor you can call up Holman-Moody and order a good aluminum intake. That way you stay with the H-M theme. 351 has a taller deck height and H-M does not make a manifold for that motor. Hope this helps..................Bill S

[JimG]

In regard to the intake, if you stick with a 289/302 stroked motor you can call up Holman-Moody and order a good aluminum intake. That way you stay with the H-M theme. 351 has a taller deck height and H-M does not make a manifold for that motor. Hope this helps..................Bill S

Yeah, that HM manifold is SWEET! Wish it could have worked on mine! You can still get the original HM cam grinds, too.

[boatnut]

Bill, Jim, others thanks so much for the flow of shared experience and knowledge. The plan is formulating: current thought is to keep the 250 (I assume the mention of a 259 drive was a typo) take it apart and paint it ourselves -- rebuild it only when our new motor smokes it, so maybe never.
Find the correct 302 crate motor to buy, check out the new H&M intake manifold or use our existing intake manifold ( we do not want to put a scoop on the hatch), and try to use our existing H&M log exh manifolds --- (they need to be inspected carefully as about 15 yrs ago some of the exhaust ports were erroding from the exh flow. I had them built up by someone with a heliarc) Have never had any problems so hopefully they can be used. I am thinking I will look for a 302 that has
300 to 320 HP with a good torque curve. (I had two of the 320 HP LT1/270 packages that you mention marined by Chris Craft -- they were dynamite packages). This engine/drive plan is coming along nicely and sounds like fun.
(our goal will be to get close to 60???)
Taking the deck off and changing the fuel tank along with all the interior hull work sounds like a lot of work though---scary. Thanks again guys, and keep the comments coming.

[boatnut]

Another thought, is H&M still a potential source of a 302 motor with their goodies --- I didn't realize they were still in business --- talk about keeping the H&M theme!

[JimG]

Call Lee Holman, he's a great guy!

Are you having fuel tank issues? My 1970's tank is original, and I'm not having any problems at all. I just run an additional fuel filter/separator and keep it maintained. Never a fuel issue.

[boatnut]

Call Lee Holman, he's a great guy!

Are you having fuel tank issues? My 1970's tank is original, and I'm not having any problems at all. I just run an additional fuel filter/separator and keep it maintained. Never a fuel issue.

Well I guess I am violating the 11th Commandment "if it aint broke---". But this forum has us (my son and I are partners on the 18) convinced that the tanks in these old vintage Donzi's are overdue time bombs. This is due to the corrosion you get in aluminum, galv steel, or even stainless when you do not allow enough oxygen (or disolved oxygen in water) to properly "protect" the metal surface --- the poor design practice of surrounding these tanks with foam (which is not an industry practice anymore) allows oxygen starved moisture and condensation to errode the tank metal and sooner or later there will be a leak and it could be significant and rapid. Some on the forum believe it is like playing russian roulette. I know from lots of marine experience that the corrosion exposure is true. For example, a stainless steel shaft in salt water will last almost forever --- but if you provide "dead water" areas such as not providing enough water to flow through a shaft log area--- the shaft within that small area will start badly pitting within a year or two and will ultimely fail. This pitting can also be seen on something like a stainless rub rail that is partially bedded such that moisture can get behind it but not adequate air or water to allow the surface to be protected---when you remove such a rub rail you will find significant pitting. Such pitting sooner or later results in gas and then fumes getting in the bilge. I still run the boat but I am trying to keep the grandkids out of it. When we get the tank out we will find out how paranoid or wise the tank change was. An interesting question to the forum would be ---has any Donzi ever gone boom as a result of this tank corrosion issue??? I would love to be convinced it is not a needed thing to worry about but as of now I am concerned. thks for the tip, I am going to contact Lee.

[boatnut]

I forgot to add: we are having no tank problems other than when we forget to fill it we have to push another boat to the gas dock with a rope.

[JimG]

I hear ya! But, if it were me I'd run it until I had a problem. I also have had a 1976 Blackfin and currently own a '79 Trojan on original tanks with no problems. I just run a good separator...

[boatnut]

I hear ya! But, if it were me I'd run it until I had a problem. I also have had a 1976 Blackfin and currently own a '79 Trojan on original tanks with no problems. I just run a good separator...

it is not the age of the tank, we have a 1965 Arena Craft in the shop that gets used once a year and it has the original steel painted tank --- but it is mounted correctly out of the bilge and so air can surround it ---as are the tanks in most old wood boats, in fact many used old car/truck tanks in homemade boats--laying a metal tank in the bottom of the deep vee (which is ideal for weight distribution) and surrounding it with foam is the problem, this corrosion problem is from the outside so you will not detect it with rust etc. showing up in a filter or separater -- that would be nice---the first symptom is gas and fumes in the bilge----or :kaioken:

[JimG]

I'm with ya. I'm keeping a eye on mine, but so far no problems.

Were the 69's and 70's tanks foamed in? I can't see any foam around mine. Maybe it's on the bottom?

[gcarter]

The problem w/ the original aluminum tank was that the metal wasn't even primered, much less actually protected. The new RDS tanks are blasted and zinc phosphate primered. With an adequate coating of coal tar epoxy, the tank is completely sealed. BTW, I still have several gallons of the epoxy.
Another issue was that the drain pipe located under the tank was not sealed, only installed w/ double sided tape. Water could and did enter the area and sit around the tank. I teplaced my pipe w/ a larger diameter pipe and sealed it w/ epoxy.
I believe that foam is the best support you can give the tank bottom. There are no hard spots to cause weakening of welds or cracks in the tank.

[boatnut]

george, I think the job you did was quality and will work as you expect -- I understand why you wanted to foam it in (maybe we will take the same route??) as it is an excellent way to place a tank into a cavity and have it supported. However in a production environment they aren't typically as careful and thorough as you are, a few nicks and the tank can corrode. Also the tank cavity can get moisture from above and from condensation even if the bilge water flow through is properly sealed and installed as you did. I just picked up a '97 22 and was very surprised to find a metal tank foamed in as well as other parts of the forward bilge filled with foam?? I'm not sure what Donzi is doing today but in the recent past they were still foaming the tanks in-- likely without the care in priming and sealing that you did.