1951 OC3-42 Smokes On Acceleration, Smooth Under Load

[Doug424]

I'll check on the choke location etc. I've taken those style Marvels apart and reversed the choke/throttle levers.

[GlenT]

I think I have the carb. problem fixed. I talked to Mark at http://www.markscarb.com/contact-us.html
He asked if my 403 carb. had threads on the carb. top section under the plug and a seat in the bottom section. I did so he sent me a power needle. I knocked out the plug, screwed in the needle, and put the carb. on the OC-3. The power needle, spring, and washer type gasket was about $25 including shipping.
There is very little smoke now and the half hour or so I ran the machine, the plugs started to clean up. I was able to kill the engine by turning the new power needle in so it is seating properly.
So, the 403 can be converted to a 406 type with a power needle.

[Blake Malkamaki]

Great news Glen. Hopefully all those carbs have threads and a seat. Good knowledge base material.

Blake