BOOM!!

BWR1953

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What size was that Jupiter? Sixteen feet? Looks bigger. And what size were those motors?

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BWR1953

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Twin 60s on a boat similar in size to my Chief. Interesting.

Those older motors were powerhead rated. My 1982-83 Mercury's may be rated at the prop and if so, would put out closer to 150HP in the older powerhead ratings, right?

Joe, do you happen to remember what MPH that Jupiter achieved?
 

Watermann

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Yeah early to mid 80's for the power rating change, Merc 82 and OMC 85. I wouldn't worry at all about there being a problem of overpowering a 1970's 150 rated OB Chief with twin 70's from the 1980's especially after being rebuilt with new materials and added knee braces..
 

Watermann

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Oh I forgot to make my prediction on the MPH achieved with twin 70's. Due to the added drag of an extra drive in the water and the Chief's heavy wind resistance I would guess 40 MPH would be very close to the top end.
 

BWR1953

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Oh I forgot to make my prediction on the MPH achieved with twin 70's. Due to the added drag of an extra drive in the water and the Chief's heavy wind resistance I would guess 40 MPH would be very close to the top end.
Yeah, I'm sure it'll also depend on the compression and power making ability of the old outboards as well. If they were rebuilt and had 200PSI in each cylinder compared to 135PSI in an older motor, it might make a fair difference.

One thing I've read over the last few months is that with twins, I can go with a bit more "pitchy" prop since there will be plenty of low end thrust to get the boat on plane quickly. I was thinking 45MPH might be the top end once properly set up if the engines are nice and tight. Not the 70MPH of my old bass boat, but still not too bad. :smile-new:
 

laurentide

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Were any 2 strokes close to 200 even when just broken in? Honest question, I've just never seen one above 150.
 

BWR1953

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Were any 2 strokes close to 200 even when just broken in? Honest question, I've just never seen one above 150.
I honestly have no idea. I've seen newer 4-strokes advertised with 200PSI so just used that figure as a general reference. The point simply being that a new or rebuilt engine will have more compression and power than a used and worn engine.

I've seen some older motors advertised with 90PSI that "run well" but I'd be dubious about such claims. ;)
 

BWR1953

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The story?

It?s all g0nef1sshn?s fault! LOL! :lol:

He posted the C-list ad for this boat and called it to my attention. That?s all it took. One look and I was hooked on the boat. So was my wife! It was just what we?d been looking for.

I contacted the seller and went through a great harangue because there was no current title or registration. That was a major issue but eventually a way was found to overcome that obstacle.

But the PO insisted on releases of liability, certified this and notarized that? totally unnecessary. The PO could have filled out a single Georgia form to get the sale done along with a simple bill of sale, but instead he chose not to go that way. So I had to take the long route. Ridiculous. :rant:

I knew it would take time to get the title worked out. My wife and I decided to just go for it and make the deal and take whatever time was needed for the paperwork. And we?re both glad that the waiting is finally over.

One item of confusion was that the seller stated that the boat was a 1977 (as in his ad) when in fact it?s a 1976. The wrong year got put onto several of the documents, but was finally corrected. The good news was that the seller drastically reduced his price.

The boat was 500 miles away and a road trip was in order! :car: This was fine with my wife because she and the boy are from the Philippines and hadn?t been out of Florida since arriving here in mid-2012.

We?d agreed to meet the seller at his place in Athens at noon the next day. We took off on Nov. 13[SUP]th[/SUP] after my wife got home from work and drove from our place to Valdosta, GA, arriving about 9pm, where we stayed overnight. We?d not told my stepson what was going on so that it was a surprise for him. He really loved staying in the nice motel in Valdosta, GA. Other than that he was pretty bored during the travel portions of the trip.

The next morning we got up early and hit the road, arriving right on schedule at noon at the seller?s house in Athens. We checked out the boat and trailer and made the deal. Then we had to work on the trailer lights. The PO had said they worked fine but such was not the case. :rolleyes: Spent a couple hours getting them straightened out but they were finally fixed. We also did some other prep work for the trip by covering the boat with a blue tarp. That didn?t work out too well once we were rolling, so it was removed along the way. :p

We stayed overnight in Athens and the next morning made the journey south back home in one trip. It took about 11 hours since we were on slow back roads for the first 100 miles. Once we hit the interstate it was smooth, speedy sailing the rest of the way. The trailer tracked straight and true and the Chieftain rode with grace and style, garnering a few admiring looks along the way. And my old truck performed flawlessly.

All in all, I?d do it again! :peace:
 

g0nef1sshn

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Glad i could help. If i wasnt in a hoa, that might have been in my backyard!
 

Watermann

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Yeah, I'm sure it'll also depend on the compression and power making ability of the old outboards as well. If they were rebuilt and had 200PSI in each cylinder compared to 135PSI in an older motor, it might make a fair difference.

One thing I've read over the last few months is that with twins, I can go with a bit more "pitchy" prop since there will be plenty of low end thrust to get the boat on plane quickly. I was thinking 45MPH might be the top end once properly set up if the engines are nice and tight. Not the 70MPH of my old bass boat, but still not too bad. :smile-new:

One can always hope for the best which is around 135 psi for 2 stroke engines of that era even rebuilt.

These Chiefs have some serious "at the wall" issues with hull design and wind resistance over 40 MPH. I can hit 40 no problem on primaries and then the secondaries start to open up and it become a real push beyond 45 as the 205 HP V6 is roaring like a monster with the pop can secondaries sucking air and fuel. Sure gets peoples attention though. :D
 

BWR1953

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One can always hope for the best which is around 135 psi for 2 stroke engines of that era even rebuilt.

These Chiefs have some serious "at the wall" issues with hull design and wind resistance over 40 MPH. I can hit 40 no problem on primaries and then the secondaries start to open up and it become a real push beyond 45 as the 205 HP V6 is roaring like a monster with the pop can secondaries sucking air and fuel. Sure gets peoples attention though. :D
Put a supercharger on that bad boy! If some is good, more is better and too much is just right! :lol:

I know you have 205HP with your I/O but you're also pulling along an extra 400 lbs. of weight compared to the outboards, if my calculations are correct.

I have a 1985 50HP Mercury that I'll be putting on my Kingfisher and it has 130-135 on all cylinders. So it should be like new? I hope so! If it performs as well as the brand new one did on my 1985 Bass Tracker Tournament TX-17, I'll probably only get 30-35MPH on the Kingfisher, which is what I got out of the BT. Never measured the compression on the BT motor though. Just used it a lot!

It'll be nice if I can find a pair of 70s with similar compression.

I think a pair of these blue stripe 70s will be right at home on the Chieftain! :D

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BWR1953

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Dang it all! Stuff like this drives me crazy. :wacko:

One option I've considered for the Chief is to repair the transom first and stick a single low-cost motor on the back just to putt-putt around and make the boat usable while I complete my Kingfisher project. That way I won't be without a boat for fishing. Might have to make two separate transoms over the long term, but I'd have the leftover plywood anyway.

And this updated ad popped up a couple hours ago. A running 70HP Evinrude for $400 with 150-145-150 compression. :facepalm: :lol:

http://tampa.craigslist.org/psc/bpo/5414106187.html

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Watermann

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Right at double the weight for the 4.3L with A1 outdrive when compared to the 2 70's. Future plans to include AL exhaust manifolds and intake which would shed about 100 Lbs of cast iron. I could even go with some vortec heads and gain 15 HP.

Heck yeah that's great compression numbers for a 30 year old OB, it's sat longer than it's been run. My 1977 55 HP Johnny was 135 psi on both cyls 12 years ago and is still going strong!
 

laurentide

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BW, I think with these older 2 strokes as long as all the cylinders are within 10% high to low it's going to run fine. I have 130-135-130 on my OMC and it runs great with lots of torque. They're closer to string trimmers than automotive engines.
 

BWR1953

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BW, I think with these older 2 strokes as long as all the cylinders are within 10% high to low it's going to run fine. I have 130-135-130 on my OMC and it runs great with lots of torque. They're closer to string trimmers than automotive engines.
Hmmm... a Paul Bunyan sized string trimmer. :lol:
 
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