1971 Tahiti Jet boat project

**jeepster21** · 10-22-2008, 06:20 PM

I propably screwd my self when I traded my 15 ft Hustler Wildcat for a 1971 Tahiti jet boat with no motor and a Berkely pump but I couldnt help my self. Ive been reading up on the Olds 455 that the boat is set up for, and it sounds to me like the motors are kinda weak druability wise. I found and automotive 455 and was going to put it in the boat with the proper marine carb,starter,head gaskets,alternator,and freeze plugs. But before I go thrugh all that work and $ and have it blow up any way i was wondering if there are any cheap, free mods that can be done to increase the druability of the motor? I know that they dont like to be reved high, Im not looking to have 500 hp or anything, just something that can stand up to a wide open run once and a while and a few years of summer crusing.

**benski** · 10-22-2008, 07:35 PM

Look on the net for some builders of hi-perf Olds motors for automobiles. If I remember right they have some oiling issues, either the oil gets pumped up and stays in the heads, starving out the sump, or the valvetrain doesn't get enough oil to it, I don't remember which issue it is. Can you put in a big Chev crate motor and be done with it?

**SSweet87** · 10-22-2008, 07:51 PM

i believe the oil stays in the heads and dosnt drain abck fast enough, not sure if thats it or not. Id throw a forged crank, rods and pistons 454 or 502 at it for a some what budget wise engine. Work over a set of good iron heads and a nice intake and have ur self a decent motor up around the 450 plus range if id say so.

**jeepster21** · 10-22-2008, 07:56 PM

I would put a 454 in it but i alredy have the motor mounts and exhaust manifolds for the olds. Other wise i would slap a 454 in right a way

**OldSleekOlds** · 10-22-2008, 11:16 PM

Originally Posted by jeepster21

I propably screwd my self when I traded my 15 ft Hustler Wildcat for a 1971 Tahiti jet boat with no motor and a Berkely pump but I couldnt help my self. Ive been reading up on the Olds 455 that the boat is set up for, and it sounds to me like the motors are kinda weak druability wise. I found and automotive 455 and was going to put it in the boat with the proper marine carb,starter,head gaskets,alternator,and freeze plugs. But before I go thrugh all that work and $ and have it blow up any way i was wondering if there are any cheap, free mods that can be done to increase the druability of the motor? I know that they dont like to be reved high, Im not looking to have 500 hp or anything, just something that can stand up to a wide open run once and a while and a few years of summer crusing.

I have been running Olds powered jet boats for more than 20 years. I spun a bearing in my first Olds powered boat after about 30 minutes on the lake. A lot of $$$$ later, I still have an Olds powered boat. I have learned it all the hard way. You are in a position to learn all the same stuff. No one told me what I'm about to tell you. If they had told me, I would not have an Olds powered boat now.

An Olds can be just as durable as any other motor IF the necessary modifications are made. A 455 Olds weighs less than a 454 Chevy or a 460 Ford. The Olds heads are so short that there is no room for a proper oil return passage. This means that any extended WOT run (like more than about 8 seconds) will result in most of the oil staying in the overhead area and the crankcase being emptied. Spun bearings (or worse) soon follow. There are things that can be done to help the motor survive. They involve a lot of work and at least a little money. Now the bad news.

ANY engine that is going in a boat requires "marine" modifications. Unless the motor has extra clearance in bearings and pistons, it will not be likely to live long. Of course the obvious starter, alternator, and fuel system mods are gonna cost a few bucks for any motor. All Olds parts cost more than the same Chevy parts.

If your situation was my situation, I would sell the Olds stuff that is in the boat and go with a 454 Chevy. It will NOT cost you any more than it will to get a "marine" 455 Olds in your boat.

If you can't handle the cost of a proper "marine" engine, the next best would be a 454 with a LOT of miles on it.....the more, the better. A lot of miles means wear which means clearance which can mean survival. An Olds with a lot of miles still won't survive without oil mods.

Good Luck

**Raceman** · 10-22-2008, 11:19 PM

Try RealOldsPower.com

Here's a link right into the forums: http://72.22.90.30/phpBB2/index.php

A lot of Olds gearheads there.

**jeepster21** · 10-23-2008, 12:24 AM

So your saying I should just get a 454 and be done with it?

**benski** · 10-23-2008, 03:45 AM

Unfortunately. that would be my recommendation..If you wanted to keep your boat "period correct", by all means keep the Olds. If you want to go kicking and screaming into the 21st century, the BBC is the affordable and sustainable replacement. If you want some more "wow" factor, a 502 or 572 crate motor would be alternative choices. Good luck with your decision, I hate to see the passing of another icon..

**Unchained** · 10-23-2008, 07:17 AM

I assembled a 455 olds for my bro in laws 70 cutlass w-30
The main problem I found was that the rod side clearance was only .0025
Chevys are around .018 - .020
That side clearance problem is a bottleneck that makes them prone to spinning rod bearings.
I had the side of the rods ground to increase the side clearance and installed oil restrictors to the top end oil passages behind the main bearings.

The olds motors can work fine with the proper improvements but they are never going to perform like a BBC and parts are always going to be harder to find.

**jeepster21** · 10-25-2008, 06:19 PM

ok this is what i got so far, i picked up a 455 yesterday complete for $100 its not marine or any thing but i have found all the marine ready accessorys like starter,carb, ect. Definatly needs to be rebuilt, the crank needs to be turnd and needs at least one piston since the skirt is broke off. If I decide to rebuild it, i will rebuild it to marine specs and clearances. if Dont rebuild it i will part it out or just sell it as is.
One the other hand i have found a Marine 454 BBC complete but then i will still need the motor mounts and manifolds and a few other things.
What should I do Rebuild, or bite the Bullet

**SSweet87** · 10-25-2008, 10:52 PM

Hate to say it but, bite the bullet! Mabee part out that 455 and make more on it then what yah bought it for.

**jeepster21** · 10-26-2008, 11:14 AM

Well i just might bite the bullet i found a 454 rebuilt, that its complete from carb to pan, including the manifolds its got an aluminum intake and some other goodies, im going to look at it today and ill get the full list of parts that it has. not to bad for $1500

**benski** · 10-26-2008, 04:07 PM

Well, in the long run I think you'll find life easier with the BBC. Good luck with it and don't forget that your Olds parts are worth something to the right audience..

**jeepster21** · 10-26-2008, 08:00 PM

i ended up buying the 454, now i have lots of 455 parts for sale, i will propably post them up for sale in the classifieds, along with some of the 454 parts that i dont need some time this week . Does any body know where i can find the motor mounts and the water input tube that bolts on to the front of the motor?

**Hippie459MN** · 11-24-2008, 06:06 PM

Originally Posted by jeepster21

I propably screwd my self when I traded my 15 ft Hustler Wildcat for a 1971 Tahiti jet boat

Where was I when you were getting rid of that Hustler? I have been on the hunt for one for a while now and short of going to Hustler Sports Center in Illinois I cant find one to save my life. lol

http://www.youtube.com/watch?v=rgSWdPfVLOo

New boat does look nice though. Cant wait to see it finished.