Finally!!!, but it bust loose on me

[Hallett of a Dream]

Well, I finally found and purchased my childhood dream, a jet boat. It's a 1976 Hallett with a 455 Olds and of course the Berkeley 12JC-A. Well, I took it for a test drive and everything seemed great. I could get 5200rmp out of the motor, stamp out about 62mph. The oil was changed in it before I bought it. The motor was supposed to have 108 hours on it, great, pretty new, right??? Guess not. After the second day of running it, I had to add over 1 qt of oil. By the end of the third day, she was knocking bad. It came on all of a sudden. Everything was fine, headed back to the ramp, running a steady 4300rpm, tried to get on it, but it wouldn't. Let off the throttle, knock knock.....uh oh. Spun the #7 and 8 rod bearings. the oil was black as coal. I only put 8 hours on the damn thing, now I am looking for a new motor. She handles like a dream and looks and sounds great, well, when it runs. Now I am looking to do things right the first time, over. any suggestions????? Yes, the first thing I did was cut the stops off of the Jetovator, but the damn brass tooth gear is seroiusly worn. HELP!!!!!

[RiverToysJas]

The two happiest days of a man's life are the day he buys his boat and the day he sells it. We all have stories just like this and if you don't, you haven't owned a boat long enough. If you're handy with motors, you can rebuild that thing w/o too much trouble. If you're not handy with a wrench, you will be soon enough. If you don't believe me, ask to see the tools that us 70s squirt boaters carry on board - I can rebuild the motor right on the river these days!
G'luck!!!!
RTJas.

[riverlover]

My suggestion, and I'm no expert, is to pick up a couple cases of bullets and start hunting around for buddies that like to rebuild motors. You might even find a helping hand here. Sorry, I can only offer moral support because I'm a newbie when it comes to motors.

[Hallett of a Dream]

I guess what I'm comtemplating here is it a good idea to buy a rebuilt marine motor, long block for $1200 and go from there? I do know motors, inside and out, but when it comes to marines, one guy tells me you can't take one out of a car and swap it in, and the other tells me that the cams are different between cars and marines. I find that hard to believe. I do believe the head gaskets are different though. I am about 5 hours from Detroit and there is a supplier that has my engine. should I make the trip?

[Heatseeker]

BOAT:
Break
Out
Another
Thousand
I have a bud that pulled a 455 out of an old Vista Cruiser wagon. The engine had 100k plus miles on it. He put it in his jet and it ran fine. That was 4 years ago and it still runs tits.
[This message has been edited by Heatseeker (edited September 01, 2001).]

[riverlover]

I met a guy at the river a few years back that told me he got a 454BBC at a junkyard. He said he went through it, freshened it up, painted it, bolted on some chrome stuff and stuck it in his boat. It ran as strong as any other boat I saw on the water. BTW, he didn't mention any special marine mods.
I'm sure someone more knowledgable about this subject will chime in by Tuesday (big weekend here)RL

[jetboatjake]

IMHO Now would be the time to think about getting away from the olds.I am no expert by any means. From what I read the chevy valve train and top end is much more dependable and also hase a better oiling sys and bottom end. I also believe the are tons more after market mods available.Drop a comment here on what your budget is and you will get tons of input.Couple cases of bullits and a rebuild would be cheapest or just pick up a crate motor.Or Call my engine guys here in illinois they are building big cube dominator chevys way dependable and big torque and HP numbers.I can help getting it out to you also.

[Hallett of a Dream]

Well, the budget isn't weak, but I can't have a Summit truck here every week without the wife having a cow and wanting another new car. As far as the big weekend goes, I have to take our other boat, a 17' open bow 85 horse outboard. But hey, it floats, it runs and burns up gas. Better than nothing I guess, but not quite the jet is it?

[Havasu Hangin']

Originally posted by Hallett of a Dream:
I guess what I'm comtemplating here...one guy tells me you can't take one out of a car and swap it in, and the other tells me that the cams are different between cars and marines.
Mercury buys its marine engines from GM's truck division. Since there is no gearbox or coasting in a boat, marine engines are constantly under load, unlike a car. Therefore, the engine is similar to a truck engine- build torque fast, and use beefy forged parts.
The main difference between a car and a boat engine is brass freeze plugs.
The cam grind may be a little diiferent, only in that it has to build bottom end torque, and not allow reversion (water getting sucked back in). This comes into play for larger cams, not the milder ones. When looking for a cam, if you stay with a cam that has a Lobe Separation Angle above 110 degrees, and an Intake Lobe Centerline in this area, with not too much duration, you should be fine. http://www.goldenplasma.f2s.com/forum/smilies/happy04.gif
If it were me (and believe me, you don't want to be me) buying that short block, I would make sure I got a forged crank and pistons, good rods, and make sure it is align bored, deck plated, and balanced. I'm sure you don't want to go through this again in a couple years. http://www.goldenplasma.f2s.com/forum/smilies/sad03.gif
Uh...my bad...wrong forum...sorry guys.
http://www.goldenplasma.f2s.com/forum/smilies/happy25.gif

[Hallett of a Dream]

I think what I'm going to do it just buy a used engine, replace all the gaskets , including the head gaskets and run it until I get my other engine built the way it should be...beefy and horsed. At least that will get me running again.

[jbj]

first you should consider a bbc. if you stay with the 455 then u need a high volume oil pump w/at least an 8 qt pan. olds is hard on the bottom end so u need more oil there,as for cam crane & comp have good selections for marine use. it has been my exp with used motors i was buying someones problems &junk.

[572Daytona]

5200rpm sounds high for an Olds engine unless it was specially built for it. At high rpms the Olds have a bad habit of leaving all of the oil in the the top end of the engine with usually a bad effect on the bottom end. You didn't say what impeller you have but if you are getting 5200 with an A your pump may need rebuilding as well. I have a '76 Tahiti with a 12JC with an A impeller with a slightly modified Olds (edelbrock intake and carb, electronic ignition) and get 64mph GPS at about 4700rpm.
There a things that can be done to the Olds to improve oiling (Bigger oil pan, restrictors in pan) but even so I would still try to avoid extended high rpm runs. Putting in a BBC is also a solution but can be pricey since you need to replace the exhaust, motor mounts, bellhousing, etc. Depending on how much you are in love with the boat and what shape it is in, it may not make sense financially. I debated for years about doing this for the Tahiti and finally decided just to leave it alone and saved until I could afford my Daytona 21 with a BBC.

[Hallett of a Dream]

Actually, the boat is in beautiful shape, just a handfull (honestly) of scratches on the hull from being beached or the occasional "missing the trailer with too much speed and not enough steerability" scratch. I may be guilty to one or 2 of those, but other than that and a new clear coat, she is perfect.
I now know of the Olds oiling probs which is why I am getting the $500 Mondello 10qt and restrictor system, but I think the biggest problem I had was letting my wife and her girlfriend take it for a run when it was only 2 days old (to me) and hearing it come around the corner. I figured it sounded a little high on the revs side which might have starved the oil pan and burnt the bearings.

[572Daytona]

Sounds nice...from what I understand the Hallet were very well built hulls it is probably worth spending the $$$ to fix her up. I still think it may be worth your while to have a pro look at your pump. With a good rebuild you can make the same or better speed with less RPM which would help you with both engine life and fuel economy

[bajaruner]

Stop now while your ahead. Although it my seem like a little more time and money today, In the big sceme of things if your going to keep your boat, and want to enjoy it, loose the OLDS.. While you can make the OLDS work, it's just not worth all the money spent only to still hope it lives, and although it's all built-up the engine still won't out live or out perform a well built Chevy or Ford of the same caliber....

[Bubbledeck2]

572Daytona what type of Tahiti do you have?
Mine is a 76 also .. just bought a GPS today and hope to get to the lake Monday and see how fast I really go. Mine is a stock 460 with a JC and according to my tach I'm spinning 4400rpm
Hallett as for the Olds, I don't know what to say .. some guys swear by them. Personally I have a problem with a motor that you have to spend money on to fix a design flaw. I'd go with a Ford or a Chevy .. in fact when I went boat shopping I'd already made my mind up that an Olds was not on my list. I'd check around to see what all the marine goodies are gonna cost you before you go swapping motors though. It may be cheaper to fix the Olds and hang with it. I just saw a complete set up for sale in the local paper here .. $1650 for a 460 Ford with a JC pump. I have no idea what kind of shape it was in, but that may give you some idea what it costs. Hope this helps.

[572Daytona]

Originally posted by Bubbledeck2:
572Daytona what type of Tahiti do you have?[/
The model is a Super Tiger it is a low profile semi-v hull. Here is a picture that I just took, it needs an interior badly:
http://www.sammythieme.com/images/dscn0552.jpg
[QUOTE]Originally posted by Bubbledeck2:
Hallett as for the Olds, I don't know what to say .. some guys swear by them. Personally I have a problem with a motor that you have to spend money on to fix a design flaw.
I don't know that I would consider it a design flaw since the 455 Olds weren't designed to spin 5000rpm for extended periods of time. I still have the stock pan on my Olds and I've never spun a bearing. Again though I only turn 4700 max and am real careful not to run max rpm for extended periods of time.

[Bubbledeck2]

572 Daytona outside of the seating arrangement and mine being a bubbledeck, the lines on your boat and mine are very similar. Someone told me mine was called a "Thunder Tiger", but I don't know that it is for sure.
Have you replaced the control cables in yours yet? I just did mine and it was fun .. not

[wsm9808]

The olds is a strong reliable engine if used within its limits. The heads only have one small oil drain back hole on each end and at high RPM (over 4500) the oil pumped to the top end can not return quick enough and the bearings get starved for oil, and well, you know the rest. Bigger oil pans and restricters in the oil passages are a popular bandaid and do help, (I personaly don't recomend restricters), but if you want your olds to live a long happy life, limit your high RPM bursts to about 20 to 30 seconds at a time and drop your cruising RPM to less than 4000. I own an engine machine shop and have machined dozens of olds motors over the years for "new" jet boat owners, most with stories just like yours on their first weekend at the lake.
A car motor will work fine, but will not be optomized for marine use. The marine cams are a little more agressive than the cars and if you bore your block be absolutely sure you have .001 to.002 extra clearance on your piston to cylinder wall clearance than a car engine. the cold lake water running through the block will not let the cly walls expand at the same rate as in a car and will gall and ruin a new set of pistons in a matter of seconds. Good luck, and enjoy your new adiction....ooops, I mean boat.

[058]

Olds engines are also prone to detonation due to a combustion chamber design that has very little quench area, almost like an open chamber design. Inaudible detonation will pound at the rod bearings like a ball-peen hammer on a piece of steel curling the bearing ends which in turn will scrape oil off the journal- result: spun rod bearing. If the compresson is kept to about 8-8.5 to 1 the engine can give excellent service for years.

[Hallett of a Dream]

I am going to keep the olds, but I am not going to be taking any chance, so I am ordering Mondello's oiling system that has the 10qt pan, oil pump and restrictors. Even though it runs $500 I think it is one hell of an insurance policy against oil starvation.

[SPECTRABRENT]

SAve your pennies and get a Big Block Chevy or Ford. Junk the Olds.
SpectraBrent

[058]

I concure with Spectrabrent, Junk the Olds and get s BBC or a BBF if you like the boat and plan on keeping it. Too many things to change and modify to get the Olds to live and they don't make that much power anyway.

[triple x tx]

turn that piece of $hit olds in to an anchor get a big block chevy.....$500 for a oil pan is f#&*ing stupid $500 will buy you a complete (REBUILDABLE) bbc toss in another $1500 to $2000 and you will have a BETTER more RELIABLE motor......there is a reason oldsmobile went out of buisness......."BECAUSE THEY SUCK ASS"

[manuel barje]

would this help? mercruiser 502 EFI 400 hours
w/exhaust,p/s pumps,oil pan,engine mounts,
flame arresters,at $2,025. on ebay #1184759512