repower??

[SLS233]

I have a 1976 formula 233. Originally it was powered w/ a 351 and omc. Around 1998 the original owner repowered with a 5.7L and cobra. When I got the boat a few months ago the engine block was cracked. I purchased a re-manufactured 5.7L, and began the install. I took it to the local shop to have the engine aligned. The mechanic told me he thought the outdrive was installed too low when the re-power was done. He explained that the "thingamajig" part of the outdrive, sorry I can't remember the name of the part (it is a horizontal fin just above the prop), should align on the same plane as the bottom of the boat when the outdrive is in its lowered position. Well, it doesn't. It's about 1.5" lower than the bottom of the boat. He explained a number of problems this might cause. The guy I got the boat from gave me an original OMC manual for installing this outdrive. In the manual there is a chart that shows install specs for installing the outdrive at +1", +.5", 0, -.5", and -1" (these measurements represent the difference between the aforementioned "thingamajig" and the bottom of the boat. Whoever did the outdrive install made some marks in the manual in the -1" sections, which makes me think he had a reason for installing it at that height. But he left no explanation. The manual gives no info on why to select which elevation. ANY IDEAS would be appreciated!

 

[JustJason]

Re: repower??

what he's talking about is the antiventalation plate.
the rule of thumb is it should be level with the keel.
But the boat is a 76.... so it's been operating that way for 32 years.
And..... it's an OMC.
Who really cares where it sits as long as it's aligned.
What are ya gonna do? rebuild and recut the transom for an inch?

 

[QC]

Re: repower??

But the boat is a 76.... so it's been operating that way for 32 years.

Well probably only since the switch to the Cobra . . .

Who really cares where it sits as long as it's aligned.

Agree. Why do you care at this point? Have you ever ran it the way it is? With a heavier boat this could be a good thing.

 

[180shabah]

Re: repower??

Don't worry about it, just have him align the engine and move on.

 

[SLS233]

Re: repower??

Thanks for the input guys. If it is as easy as just going ahead and aligning the engine and moving on, I'm all for it. My concern is, and my question is, if the engine is too low what's the possibility of water surging into the engine through the exhaust. The engine that was installed at the first repower had a crack in one of the cylinder walls. The back cylinders were completely frozen from rust. There had to have been water in the cylinders from somewhere. I'm not sure if the crack in the cylinder wall was from freezing, or is it possible, that was a result of a waterlock? I don't know wheather an inch difference is an issue or not. In golf and football it can cost you the game. In a boat, can it cost me an engine? Any Ideas???

 

[Don S]

Re: repower??

The back cylinders were completely frozen from rust.

I wouldn't take a boat out on the water that was freed up after being frozen with water and rust. The cylinders and pistons are scored, the rings are probably not working because they are frozen into the piston. Your engine has hours to live, not years.

 

[QC]

Re: repower??

Don . . . that was one engine ago . . . one inch is probably not going to have any significant impact on reversion . . . The water in the cylinders at that time could've been from a head gasket etc . . . Maybe reversion, but hopefully the flappers are where they belong and the risers are still well above the water line . . . Just be especially careful when you come off plane to do it slowly and give a little burst of throttle just when she settles. You shouldn't have any problems as long as it will align properly.

 

[chiefalen]

Re: repower??

Sir: We are talking about a stringer here.

Leave that drive alone as long as the engine coupler is good, the proper sized flywheel, the shaft is good, the ball gears good?

Water pump good? Last time you put in a impeller, inspected the water shafts?

Inspected the gears?

 

[rodbolt]

Re: repower??

if it was actually repowed in 1998 with a 1998 package you have a Volvo. so before we get to far into this we really really need a positive ID.
Volvo did away with exaust flappers years and years ago.
however a good thing to check is the static water line.
Volvo says from the top of the riser to the static water line must be 13.5".
if less, riser extensions are nessasary.
the X diminsion will vary with transome angles so its hard to say where your center line will be as we dont know the angle of the transom but its all in the installation manual.
on an outboard anti-ventilation plate we typically see 1" above or below the hull bottom. most stern drive plates are 1.5" to 3" below the hull.
but like I say,X dimension is determined by transom angles which vary all over the place even among production runs and between hull designs.
myself I would simply align the engine,then reassemble everything, then with a normal load and the hull sitting in flat water check the static riser water line.
if its greater than 14" go boating,if less than 13.5 buy the riser extension kit.

 

[QC]

Re: repower??

Yes, what he said ^^^^^ . . .

 

[GiMLit]

Re: repower??

I think this thread gives a couple really good examples of
#1 people not reading what is already in the thread and specially the first post.
#2 good ideas and willingness to help.

Problem is if you are guilty in #1 you can often give wrong/bad info in #2

According to what you have said, you have a hull orginally powered by an OMC stringer. It was repowered and fitted with a Cobra drive. This would mean a rework of the transom to fill in the hole the Stringer drive occupied and give a surface to mount the Cobra on.

Yes your drive might be a little low to be considered ideal.
No, not likely that it would cause a problem with reversion of water by being an inch low, I guess not impossible but very unlikely.

IMHO if you had the desire and know how and wanted things to be perfect then go to and and redo the transom etc....
Reality is you took it to someone else to repair it so you likely do not have one of the 2 prior ingredients (not a slam or hit on you in any way) so I woudl go boating and have a good time!

Hope I helped.

 

[HT32BSX115]

Re: repower??

I have a 1976 formula 233. Originally it was powered w/ a 351 and omc. Around 1998 the original owner repowered with a 5.7L and cobra. When I got the boat a few months ago the engine block was cracked. I purchased a re-manufactured 5.7L, and began the install. I took it to the local shop to have the engine aligned. The mechanic told me he thought the outdrive was installed too low when the re-power was done. He explained that the "thingamajig" part of the outdrive, sorry I can't remember the name of the part (it is a horizontal fin just above the prop), should align on the same plane as the bottom of the boat when the outdrive is in its lowered position. Well, it doesn't. It's about 1.5" lower than the bottom of the boat. He explained a number of problems this might cause. The guy I got the boat from gave me an original OMC manual for installing this outdrive. In the manual there is a chart that shows install specs for installing the outdrive at +1", +.5", 0, -.5", and -1" (these measurements represent the difference between the aforementioned "thingamajig" and the bottom of the boat. Whoever did the outdrive install made some marks in the manual in the -1" sections, which makes me think he had a reason for installing it at that height. But he left no explanation. The manual gives no info on why to select which elevation. ANY IDEAS would be appreciated!

Howdy,

I worried about your very concern when I removed the King Cobra and replaced it with the Bravo.

When I put the 2 drives side by side, I discovered that the distance between the crankshaft and the propshaft were essentially the same. (And the anti-vent plate for both were in about the same place relative to the bottom of the boat)

My point is, if they had been different, by an inch or so I would have still installed the Bravo. I don't think it would have made huge difference.....

For yours you're essentially stuck. It's installed. unless you want to remove it and re-do the transom like someone indicated above, just run it.

The downside of having the drive a little lower is additional drag and maybe a slightly lower top speed......but if the install manual indicates plus or minus 1 inch as an acceptable tolerance then don't worry about it if you're only 1/2" lower than that, and it runs ok, just go boating.

If it bothers you a lot. Then find yourself another boat and part that one out (or sell it and tell whomever buys it what's going on)


Cheers,


Rick

 

[rodbolt]

Re: repower??

and Gimlit is guilty of not reading
the last of the OMC Cobras was avalible in early 94,after that it was a joint venture cobra SX that lasted until about 95 then Volvo bought OMC's stern drive division outright and EVERTHING since was and is Volvo.
by the statement"repowered in 98" it would lead one to believe that it is a WT model volvo.
however its not uncommon to sell a "new" 3 year old motor in the crate.
thats why I asked for a positive ID.
we still dont know what we are dealing with.
however the static water line was the same for both the cobra,the JV SX and the Volvo SX.
as the economy goes more Global it gets funnier and funnier. about the time OMC sold the stern drive divison to Volvo, volvo sold their automotive side to Ford. hence no more rubber band inline 4 and 6 cyl Volvo pentas.
then ford withdrew from the marine market about 95.
then about 97 or so Volvo spun off again and dropped the Penta name.
dont even get me started on the 700Billion cash for trash deal

 

[HT32BSX115]

Re: repower??

Yeah I don't want to go there either.

I guess I could have put a pic in there for comparison. everybody likes pictures.....

I think ALL the stern drive manufacturers made everything "the same" to make it easier for hull makers.....

 

[rodbolt]

Re: repower??

yep, ya shouldda worked in this industry before BIA standards.
nothing interchanged and sometimes no interchange in the manufactures line.
made figguring out what you had and how to fix it interesting.
something like 2 sizes of steering cables,maybe 7 styles of mounting the steering,more contol box cable types than I care to remember and we wont even talk about engine/outdrive mounting bolt patterns.
and now it seems to be heading the same way again.
makes it tough on the consumer but so does this 700B cash for trash deal.

 

[SLS233]

Re: repower??

Thanks for all the info. It seems you all are in agreement that its not such a big deal about the x dimension being an inch or so below the hull. I guess my next step will be to check the distance between the static water line and the top of the risers. If that looks good, I'll fire it up and take it for a run.

 

[chiefalen]

Re: repower??

Yes leave it alone.

Yes i missed the part where it was re-powered by a cobra.

Yes i thought he still had a stringer.

Yes i can't read as good as i used to, must be the diabetes.

Yes i was trying to help.

 

[Boatin Bob]

Re: repower??

You know as long as we are talking about not reading everything I think some are guilty of reading too much.

No where did I read that when it was repowered in 1998 does it say with "NEW", for all we know they could have taken the complete package out of a donor boat and repowered this one with it? So it really could be an OMC 5.7 with a Cobra, if the original poster had posted the model from the engine or drive we would know what year the unit was.

 

[SLS233]

Re: repower??

Oooops! Well, some people can't read and then there are those who can't type. I guess I fall into both categories. In the original post I said It was repowered in 1998. Actually it was in 1989 with a new 1986 engine and cobra. Engine #574pmkwb. Sorry for the confusion. However, I don't see that it changes the bottom line. I really appreciate all the help! I'll post again once ist in the water.

 

[GiMLit]

Re: repower??

I was in no way intending to insult anyone with my comments.
While reading through many threads I have noticed that as they go on they go farther and farther off track etc..... assistance is great, I have learned lots on this forum. My point was wrong info or misguided info based on wrong application etc.... could have someone spending time and or money that, or god forbid panicing, for no reason at all.
Offer assistance, it is what makes places like this so great, just make sure you have all the details correct before you do.

Later