Engine Data Plate Change

Fresno plates need a lot of stamping, Ware as other on the net for C85s need less. Most upgrade I have seen are 85 stamped over the 75. Plus, check casting number on the intake web block My brother got dragged in on one that was still for a 75 it had got wrecked and FAA was looking for why.

PS:
Since its your first annual, etc, your mechanic may not be familiar with the process of changing a data plate. Suggest he call DIVCO, and discuss procedure - they have to do it when changing an engine case that is beyond repair, etc. Just explain to them reason - it's not a teardown. 2c

If all you need is a new correct/updated data plate. Check with FRESNO, if IIRC, I think they use to advertise the blanks ( they looked just like the OEM). You can use the dies and stamp appropriately and, of course, note in engine lob book with justification.

Years ago, if one had a damaged one, IIRC, that "TCM", would provide a replacement but required a letter from FAA authorizing.
FWIW

There are entries in the logbook for the carb upgrade (Marvel Schebler) and retuning for 85 hp.  Subsequent entries continue to identify as C-75.  But the prop has been shortened to 69.5 " and the engine turns 2450 rpm in cruise.

During my first annual inspection on my 1947 415C we have found the engine has been upgraded to 85 hp.  However, the Type Certificate and the specified Service Bulletin (M47-16) indicate the engine data plate has to be changed to C85-12F with the existing serial number.  Continental Motors will not make a new data plate for the upgrade.

Does anyone know of an alternative to this situation.  My A&P/IA is reluctant to sign off on the current configuration.

Thank-you