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There are some posts around the internet, including post #4 in that BRF link above, that make mention of pistons and rods for the 1975 model year of the 75hp.. I can confirm that the rods are not unique, but used on the 3cyls from 1971 to 1975, and also a few 25 and 35hp models. Also, yes, there are versions of earlier pistons that are lighter. I have a couple in hand and weighed them. Those have thinner skirts, and slightly domed tops. The heaver ones with more piston above the top ring are approx 40g heavier than the 1975 pistons.

I wish there was a good source for cross referencing casting numbers with part numbers.

so many different 49ci pistons..

Far left is a 1968 55hp 3-ring piston. The top ring is low, the skirts are thin.
Far right is the one piston from the 1975 75hp Stinger block that I recently got my hands on. Likely original to the block. Casting 320645. Top ring is high, flat top piston.
Others are everything in between in terms of model years and horsepower; top ring is high; they are domed tops.
Except for the one piston above the rest: it is a flat top with a lower top ring than the 1975 Stinger piston. Casting 319295.
Unfortunately, I don't know the true origin of the other pistons.. They came in obviously rebuilt "junker" blocks.
The 319220 casting is a lot like the 1975 stinger piston but domed. I'm assuming all the domed top pistons are for the older style combustion chamber so 1973 and older..

When I started this thread here is an example of what I was referring to.
Low cost original 75 hp powerheads.
You need to check them, but if they don't need a major rebuild only a hone and gaskets.
They run very well and last.
15 inch triple mids and twin cylinder nitro cases are around. Not that costly.
You can cut and weld to make the triple 15 inch drive shaft
The 49 works well with the higher ratio twin gear ratio
https://www.kijiji.ca/v-powerboat-motor ... 1476897168

I have a mint 49ci with fresh dark grey painted cowl pan and mid. Its complete minus a lower. I would sell it to free up some cash for racing equipment Im in need of.

You could add a 2cyl nitro lower for $300-400 and have a cool little motor.

I was thinking about doing this myself but it will never happen lol

I believe the gear ratio of the twin nitro case is the same as or close to the ratio of the large gear case. We ran SST60 props 23 and 24 pitch with the twin nitro case and a 49, they ran well. Lots of punch. Not sure if the twin nitro case would work with a mod 56'r for drag racing. Likely need to cryo the parts to make them stronger. But you would think a 24 or 25 pitch and 13 diameter prop would get you out of the hole quickly and run 70 mph in 660 feet. Now the SST60 gear case with a twin gear set would provide better top end due to the longer case and nose cone.

I took the intake of my 49.7ci 3cyl apart to completely rebuild the carbs and noticed a reed was slightly wak.
Happen to have hoarded a set of CCM reeds a little while ago so that's good.

And now I've run in to a few bumps along this journey:
- I am looking for an intake gasket. IM to Block for the 1984+ block. Anyone west of the big city have one?
- What do people do to increase the reed stop height? Mine measure .210 to .220in. Spec sheet for 49.7 FE says .280


regarding the IM gasket: see how it has the quarter round curved hole on one end:

Or anyone travelling from Lindsay area to Guelph this weekend? I have several of these gaskets.

At this point due to weather and such, I'll just phone local shops on Tues..

Still looking for advice on the reed stops!