'49 Olds 303 water jacket restrictors.

[Seedee]

So, in my slow preparations before sending the block out to the machine shop I noticed these orifices or "restrictiors" that look pretty corroded. At the front of the block on both sides. I can't tell if they were casted (which I highly doubt) or are they a type of core plug punched in during assembly. Fearing they won't survive the cleaning process I'm curious if there's a mention of these "restrictiors' in anyone's parts book? Or I have to fabricate a replacement.

You can't tell in the photo but there is a lip around the opening. I figured best would be just to drill the same diameter into a steel core plug and drive it in. But any insight would be appreciated!

Edited July 4, 2022 by Seedee (see edit history)

[Larry Schramm]

I would say required to control coolant flow evenly through the engine. Not that unusual. Sometimes you see them as part of the head gasket.  I would definitely keep them and replace them if the do not survive the cleaning.