Chatham Engine Rebuid: Carberators
JP comments that the carberators take a completely different mind set to rebuild!
1) Assumption is that all rubber gaskets leak and must be replaced.
2) Test floats and valves and seats
3) Clean/inspect vacuum pistons and pots and check slide. Polish if necessary
4) Inspect jet needle
5) Clean passages
6) Bolt hole threads on intake manifold are usually stripped from over tightening or repetitively removing the carbs. They will need to be machined to oversize, or better yet, heli-coil or the like.
7) Intake manifold will not be touched unless leaking
I think I take JP's addage one step further, assume mounting bolts have been overtightened and all threads are stripped, assume you will need to replace all of the working carb parts and in the case of the carbs, cleanliness is next to godliness. I have heard of people spending inordinate amount of time cleaning jets and making gadgets to remove gunk from the carb parts, but unless your time is free, the only way to make a reliable set of carbs is to do a complete rebuild.
Ortmann, CMSnl, Spread Tool, Eurasia, and Ricky Nagata, all supply rebuild parts for the carbs. They are not inexpensive, but the amount of work that goes into re-building a carb set, I think it pays in the end to replace anything that can be faulty. In this case, some of the dirtiest float bowls ever seen!
Ortmann supplied gasket does not seem to fit and a new one will be cut. We ended up replacing with a gasket set from CMSnl.
The linkage bushings were worn out, they were rebuilt sawing slices of a nylon pipe and replaced
It seems as if the fuel delivery system had been modified? These screws are not original.