AC Delco upper engine cleaner

[Flathead16]

Has anyone used the GM upper engine cleaner to decarbonizing your piston and valves? With the lack of timing in the 1938-1940 V16s carbon is a problem and could cause some of the valve sticking problems and weak spring combination.
Thank you, Steve Loechner

[Jon S]

I would think Sea Foam (a modern day version of Carb Out) would work.

[cadman59]

A couple off days ago I stumbled on a message in this old topic. Maybe that would work for you too. At least it seems to be a "period-correct" method  .