OldIHC

Can someone please explain to me the purpose of the metal rod that is inside the water jacket of the cylinder head on the green diamond 233. The old head that I removed from my '48 KB-5 and the NOS head that I purchased both have a rod inside the head that runs almost the entire length of it. It is about 3/16th inch in diameter and it is loose. Move the head and it rattles.

I would guess it is for rust prevention like the anode in a hot water tank. I am just guessing. Both heads I have ( 1 installed and 1 spare) have them as well.

Will be interested to know. I bet if someone called Pappy Vance, he would know for sure.

I agree, I would say it is an anode.
Bill

I think it had to do with stablizeing the core sand during casting. Many heads I've seen have rods or wire. I doubt it has anything to do with corosion, as these are sacrficial and need to be replaced where used. There should be no need on a closed system, as these can be treated with additives. Anodes are used when sea water or lake water is used for cooling in marine applications.

CB, that makes a lot of sense. One thing that I found very interesting about the wire, is that it is absolutely straight. IF it were inserted after casting, I would expect that it would be slightly bent because of the "sharp" bend to go into the water jacket on the head.

So, that probably is the correct answer.

I'd agree with casting theory,plus an anode would never last 70 years.

FWIW,
Hot water heaters have anodes too. Your HWH would last much longer with a little maintenance,drain it once a year and replace the anode about every 2 although that can vary,check the manual.
Just like a vehicle,a little PM goes a long way.