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BANG FOR THE BUCK.... GO 49 OMC...CHOOSE WISELY

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 PostPosted: November 4th, 2019, 4:36 pm   
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Hey Matt, go to the APBA web site for engine specs.


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 PostPosted: November 4th, 2019, 7:24 pm   
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hec2buck wrote:
Hey Matt, go to the APBA web site for engine specs.


I don’t think it is listed as the motor isn’t raced anymore except in some regattas

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Bullet 20 cc Super Comp
Delta with a slow 56
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 PostPosted: November 4th, 2019, 8:05 pm   
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I couldn't find it on apba.org, but some folks have it.. Don sent me this:

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Critchfield T850 OMC 75 49ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: November 4th, 2019, 8:07 pm   
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At this point, I'm looking for details: Exhaust Port Height "B" -> what kind of chamfer is allowed?
I've never seen a photo or anything showing the 1975 block exhaust port chamfer/deatils..

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Critchfield T850 OMC 75 49ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: November 4th, 2019, 10:25 pm   
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 PostPosted: November 5th, 2019, 5:37 pm   
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Critchfield T850 OMC 75 49ci
Delta T750 Yamaha 55
1989 Voodoo Yamaha 70
1980 Thundercraft v142 Restored


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 PostPosted: November 6th, 2019, 10:44 am   
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Most of the FE and SE racers ran motors right out of the box. For approximately $900.00 OMC Peterborough would sell you a new motor and choice of prop. I had no experience with the OMC motor until mid 1990's. I thought I could build a very good motor using all brand new parts and have Gord Bush blue print it for me. Very costly project! The boat was competitive. After a Saturday race I noticed scoring in one cylinder. I decided not to race it on Sunday. Another racer offered me his back up junk powerhead to run on Sunday. We tested on Sunday prior to the race. That motor turned 6800-6900 compared to my 6400 to 6500. So the article above is very true. The 49 was produced between 1968 and 1988 with the last version being the Formula E. The last version had a forged steel crank not cast crank. Since my mid 90's experience I have had several 49's. I found it was very easy to get any of the STOCK 49's to turn 6200 to 6400 on a V hull. It was a challenge to get one to turn 6800-6900 and impossible to get a 6200-6400 motor to turn 6800 regardless of the money you put into it. You had to have a GOOD 6500-6600 to start with. I am talking pure stock......not any of the 180-200 compression motors later racers ran in EP and T850.
In my view the 74 to 76 blocks are the best and they can differ. You need the small 150 compression stinger head and the 1.5 bore carbs, plastic reeds and maybe? 19 degree timing. There are lots of old 74 to 76 GOOD powerheads for less than $200. Clean one up and switch the parts. You will be surprised at the performance. It does not make dollar sense to spend big money on a 49 now that you can run a 56'r.


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 PostPosted: November 6th, 2019, 3:30 pm   
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I have a beauty low hrs '88 sprint ss.
Big 1.5" carbs, reeds etc.
Ive been trying to sell the powerhead for $600 with no sucess so I think I'll keep it and build a gearcase. Might be a good motor for something I shouldn't buy lol


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 PostPosted: November 6th, 2019, 3:31 pm   
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Streamin wrote:
I have a beauty low hrs '88 sprint ss.
Big 1.5" carbs, reeds etc.
Ive been trying to sell the powerhead for $600 with no sucess so I think I'll keep it and build a gearcase. Might be a good motor for something my wife says l dont need lol


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 PostPosted: November 6th, 2019, 5:03 pm   
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I will give you the same advise I gave another fellow with a 1988 49'r.

Your 49 has good parts that fit a 56'r!
- the 4 spline steel crank
- the big carbs and primer.....just need bigger jets
- flywheel
- CDI electronics only need longer wires to mount on 56 bracket and they are way better than the later China stuff.

LOOK FOR A RUNNING 56 oval port!
EXAMPLE:
https://www.kijiji.ca/v-powerboat-motor ... 1456586578

Switch the parts over from your 49 to the oval port.
You can sell the extra parts from both motors on ebay.

A couple of things to remember.
[1] the oval port requires only a port clean up to perform. Bridge ports require costly machine work to get equal performance.
[2] using running GOOD motors saves parts costs....clean up....honing...seals and gaskets....should be all you need.


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