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I my view the best low budget T motor is the T750 OMC twin.
The only problem with it is the drop in performance on lake runners that are heavier.
Most lake runners are going to the 56 omc.
Most of the 56 motors are basically stock motors on 15 inch mid with nitro cases.
Once you get into the T850 race motors the cost increases and most do not build an altered T850 OMC.
Most of the used nitro casts are worn out and the cost for new nitro replacement parts is VERY costly.

NOW LET's LOOK AT THE 49 OMC 1973 to 1975 powerheads.
You only want to look at those years....THEY ARE THE BEST!
Best porting and lightest rotating mass.

HOW GOOD ARE THEY?
On another thread I posted the 1976!! EP 5 mile record at 60 to 61 miles per hour. That record was set with an out of the box 49 OMC in 1975! Paul set the Canadian EP 5 mile record in 1991 at a similar speed on a lighter hull and with power trim. The SE and SST 60 mile records are both in the 90's miles per hour with only a few miles per hour difference.......put the SST60 nose coned lower unit on the 49 OMC and they would be almost the same.

I would keep running the originally nitro until it broke.....
I would change to the twin nitro case rather than spend $1000.00 or more to rebuild the original nitro.
You can buy a twin nitro complete lower unit for $200. to $300. and so far all the used ones have been excellent condition.
AND the 3 cylinder drive shaft fits.

I was asked....Why would you NOT just rebuild the 56, it costs the same money?

A year ago, I would agree. The cost of the nitro lower unit replacement parts, the cost of the 49 parts, the fact that the twin nitro case cannot handle the torque of the altered 56 and the fact that most lake runners run in the 60's mph are the reasons.

HERE IS A 1975 75 hp PARTS BOOK:
https://www.marineengine.com/parts/john ... =75ESLR75B

BANG FOR THE BUCK!!
You need a 15 inch 49 mid and drive shaft....everything else is easy and CHEAP.
There are long shaft twin nitro parts motors for sale all the time...cheap.
Because the majority of the 49s were on long shafts and were not oil injected there are lots of good ones.
You can use a 73 or 74 short block provided it has the good porting.
The 75 year has everything including the head which is a must use.
You can find this stuff cheap or even free.
New original rings and pistons are on the web and you can get them cheap.
By selecting a good block you will not need to go oversize....just new rings.
Carbs and ignition parts all work.

For under $1000.00 you have a rebuilt good running 49 short with a very good nitro case.

JUST TO ADD:
The drive shaft can be an easy fix.......just cut and weld a junk 49 on to the twin nitro...that way you do not need to take the nitro case apart to replace the drive shaft.....less cost.

Another problem with ALL stock OMC 49 15 inch mid and clamp brackets is the extra hard to find separate side brackets.
There is a simple solution for that as well.
https://www.marineengine.com/parts/john ... Midsection

Part # 97......................https://www.marineengine.com/newparts/p ... OMC0325914
This bushing will fit in the clamp bracket of ANY steering tube model side bracket and allow you to run a bolt in place of the tube.
You don't need the original extra brackets.
Part # 83.......................https://www.marineengine.com/newparts/p ... OMC0325017
This clip fits on the bolt and presses against the bracket so you can tighten the bolt.

Most of the raced mids have play in the bracket....this fixes that problem...plus you could use narrow side clamp brackets and make the overall assembly narrower so it fits on the narrower and lighter PT35 CMC trim unit.

I have an extra set of brackets i’d sell if someone is looking.

FROM ANOTHER THREAD
There were several equipment changes that happened before the 1998 race season.
- the lighter Marty Brodeur Critchfields were running....Both Steve Wrong and Jim Whittington had them.
- the new 59 cubic inch Mercury was running...both Brian Sherriff and James Allen ran them
- the 70 Yamaha was running.
As a result the mod VP never finished any better than 4th in a heat in 1998.
Steve Wrong won the Nationals with a 49 OMC. THAT BOAT ENDED UP WITH JUNIOR.
The mod VP never raced after 1998.

HOW DID STEVE BEAT THE YAMAHA, THE 59 MERCURY'S, THE 650XS MOD VP'S WITH A 100% LEGAL 49?

CAM MORLEY!!
It wasn't until Cam stopped racing that he and I talked about OMC 49 motors. Cam built the race 49's for Steve and himself. Cam won EP high points one year and for a fellow at about 300 lbs that is an accomplishment. Cam never had one of his motors fail inspection. I learned the history of the 49 from him and he told me about the changes made in the motor between 1975 and 1986. The major changes were the porting, the crank, the carbs and the ignition. The changes made the motor more user friendly and less racer friendly.
As a race motor the 1986 Formula E was a 64 to 66 mph motor compared to the 1975 Stinger/Hustler that were 68 to 70 mph motors
on that SAME boat.
Cam said the the APBA spec sheet for the 49 was based on the 1975 model. He said you could not even blue print the later model blocks to the APBA spec. That spec gave the motor more top end.
Cam had played with the 1972/73 65 hp lighter flywheel, but was not impressed. He did like the primer style carbs, but they didn't make any difference performance wise compare to the original butterfly style and he liked the early 80's ignition.

We got our brand new in the box 70CES in 1997. We didn't race it in 1997 because it was not fast enough. It ran 63 mph. It took us the complete summer of 1997 to get it to run 67 mph. Before the 1998 race season we helped and tested with Brian Sherriff who was running the new 59 Mercury. The yamaha and mercury run the same props so Brian got competitive quickly. We learned a lot with the Le Mans docket starts. If we ran a prop that gave us 68 mph, the Mercury was faster than us to 60 mph every time. But both boats were quicker than a 49 OMC off the dock.
In the first races in 1998 the run to the first pin was a good distance and the OMC couldn't catch us. Once Jim got the lead he just out drove everyone to win.
The Nationals had a very short run to the first pin. We didn't have a prop small enough. We were lucky in the starting draws and won the early heats. Steve was second all the time and getting closer and closer to beating us to the first pin every heat. For the final he beat us easily and won.

Here is an example of a 49 OMC RAT motor.
That motor still has it's original compression.
I has a big cylinder head and would get 145 to 150 by just bolting on the 1975 75 hp head.
Seller will likely not get any offers
https://www.kijiji.ca/v-powerboat-motor ... nFlag=true

Thanks Don.
Learning a lot from your posts.

The 20 inch shift rod off the twin nitro and the 15 inch mid sections.
The early 15 inch triples were electric shift and had no shift rod hole in the mid.
The steering arm weld does not allow the head of the shift rod to pass thru.
You can drill the hole in the early mid for the rod.
Rather than grind the weld to make the steering arm larger just cut and thread the 20 inch shift rod to size.
Add a connector to join the rod at the bottom. Now you can feed the rod from the top thru the steering arm
and join the rod.
This alteration also works when you run a long shaft 56 base plate on a 49 nitro. The 56 base plate is thicker than the 49 so the 49 shift rod is 1/4 inch to short. using the connector allows you to adjust the length so the motor shifts perfect. Many just have the motor in gear all the time rather than fix it.
You don't need the connector if you don't want too. Because it is a push-pull shift, cut the rod and flatten half of each section, mate the two, clamp the pieces at the correct length and drill a small hole thru both parts, then insert a pin thru the hole.

I was asked about the lighter flywheel....it is not that much lighter.

It was only on the 1972 65 hp...and it works with the later ignition as well
http://www.drolsum.net/johnson/iboat/2.jpg

Here is the later 49 ignition and primer style carbs.....later 70 hp 49's had smaller carbs....the larger primer carbs were on early 56 ..70hp models.
https://www.smalloutboards.com/images/e7085/inside.jpg

The ignition system mounting plate from the 56 will mount on the 49 and I believe the complete 56 ignition works on the 49.
You can mount the later model 49 ignition system above on the 56 mounting plate by making the wires to the parts under the flywheel longer.
http://videoclipsimage.agaclip.com/aga/ ... unning.png

Just a note:
For the SST60 class you had to run the original OEM parts. There were only standard and 30 over pistons that you could use. The short life of the powerhead meant you went from standard to 30 over to re-sleeve in a very short period of time. Testing put time on the motor so most did not test much in the 1 hour test time prior to the race. After blowing up two motors testing and loosing a heat because of a failed [CHINA MADE CD BOX] ignition I built a test only powerhead, I took a blown standard bore and bored it 20 over and used aftermarket cast 20 over pistons. I mounted the American made 49 ignition onto the 56 ignition mounting plate. We ran that comb in testing and then put a legal powerhead on before the first heat. When the 20 over powerhead got re-built we bored it 30 and put legal ignition on it.
I built 3 of these over the years using the same 49 ignition parts and the 49 ignition NEVER missed a beat.

Anyone have the 49cu.in. spec sheet? Or know where I can find it?

thanks,
M


edit: also looking for 59D and maybe 61D jets.