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The Gordon Group in their Gravenhurst Video mentioned they would be refreshing Chris’s Bridgeport and they had Eric’s Bridgeport already in process to be completed prior to the next event. I believe at the Gravenhurst event with 9 entries..7 were Bridgeport motors and 2 were oval port.
One reason why there are more Bridgeport motors is the engine build results in a more consistent Good performance outcome compared to the oval port. Several oval port builds haven’t made it to the race course because they aren’t performing as expected, so those motors are still in the works , but racers are replacing them at the races with their Bridgeport motor hoping to solve the problem with their oval port between events.
Many racers are realizing that the life span of their motors is dropping faster than expected and the class is seeing more mechanical issues than in previous years.
Simply put...once your start pushing your equipment to the extreme....things break more often.
In a short race season you fall out of the championship race with a poor result at just one event.
The level of race preparation has to improve. You need to reduce the number of things that can possibly go wrong. You replace things before they break. You may decide to run only you race equipment at the event. You don’t test or do lake runs with it. You save the running hours on the equipment for racing only. It’s a learned experience. That racers should think about.

“Don, I found this on boatracingfacts about rebuilding a 70 Johnson. It has a lot of information.
https://www.boatracingfacts.com/forums/ ... 70mod-quot“

That is a lot of posts! I hadn’t seen that before and I am not knowledgeable about mod stuff. I noticed both Kevin and Paul have posts. So maybe they could comment on how much proven good information is there. Back then the T850 racers were building OMC 56 motors based on the revised engine spec rules. Since then the T850 racers have learned from racing these altered motors more about what works and what didn’t work.
Sorry I can’t provide anything more.

I didn’t have anything to do last night so I thought I would educate myself and read thru all 300 plus posts.
It was a waste of time!

Most people when they rebuilt their motor want to make it better. It doesn’t need to be a race motor, but since they’re spending money rebuilding it why not do somethings to make it better and last a long time.

The most important fact is production motors are not exact and the manufacturing process itself creates wide variations. Some major, some minor. Simple truth is correct those variables and the result will be a much better performing motor.

The best motor to rebuild is yours! You have a history with the motor and if it has been a good performing motor until it failed then check to see what caused it it fail and what needs to be done to fix it. Refreshing a two stroke with new over sized pistons, bearings and seals should make the powerhead as good as new.

Since your spending the money..... fix the variations when you rebuild it.
Match port and straighten their edges. That makes the same port in each cylinder the same size and you have fixed the wavy edges on the ports. Check to make sure the sleeve(s) haven’t turned in the bores. Grind away any aluminum casting you see that extends into the ports. The block will need to be bored oversized for the pistons and honed for the new rings. Have the machine shop surface the block and cylinder head.
If you want to increase the compression you can ...but don’t make the cylinder head smaller cc than at SST 60 specification. You don’t necessarily need cut the head, but you want the head and block to be straight.
https://www.apba.org/documents/71326379 ... 11515A.pdf
I would replace the reeds and you MUST clean the carburetors! Remember to replace the water pump impeller. And engine thermostat
There is a noticeable difference in performance with just making these changes in a STOCK rebuilt.