Head gasket


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Golden Jubilee
Golden Jubilee

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Post Sat Sep 12, 2020 12:28 pm

Re: Head gasket

sacrificial rod, same as in a home hot water tank, theory is water wants to corrode, give it something to corrode and it will not corrode head material as fast,

or some kind of mafia style bribery thing
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Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sat Sep 12, 2020 3:57 pm

Re: Head gasket

Yeah, its there to stabilize and hold the core sand in place. For it to be a sacrificial "rod" it would have to be of different metal than the head (zinc is most common). When casings are made with "coolant passages" green sand is used where you don't want cast iron to be. After the casting the sand is shaken out but the rods used to hold it in place can't come out. You will see them in lots of castings with internal passages. They will be in the block and head.
If you picture a cut away of a head or block, you have iron surrounding a "void" with cast iron all around. For that to happen you must put something in the mold to prevent the iron from forming one big lump. How do you "suspend" something in the center of the pour? you put a rod through it the extends right through the mold, After the pour cools, the rod is trimmed where it stick out and left in the void where it held the sand.
If you were really anal , you could try and cut it into little pieces and extract through a hole, but it will not do any harm where it is.

Golden Jubilee
Golden Jubilee

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Post Sat Sep 12, 2020 5:39 pm

Re: Head gasket

C89 thanks for the lesson. I guess I must be really anal because I removed it all; figured it wouldn’t hurt anything .
Pulled a couple plugs to get a quick read. Was only twenty miles on them but I did it anyway. Mostly wanted to look at #3 as it a sign of moisture in the squish chamber. Dry and clean so far.
Started installing remote Anderson connector for battery maintenance and maybe a jump if needed.

Golden Jubilee
Golden Jubilee

Posts: 4575

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sat Sep 12, 2020 5:51 pm

Re: Head gasket

I've made exactly one mold and and the metal poured was aluminum. It was in shop class, back when public schools had such a thing, but the shop teacher made sure we knew the basics and he was the one who told us about the rods or wires.
He posed it as a question, how would you make a coolant passage in a block casting? He let us stew all period before telling us the answer. None of came up with it on our own.
It was fun pouring aluminum, but I would like to try cast iron someday, will not likely happen at my age.

Golden Jubilee
Golden Jubilee

Posts: 340

Joined: Sun Nov 15, 2015 8:16 am

Post Sun Sep 13, 2020 7:04 am

Re: Head gasket

Ah yes..shop class. A shame to see them go. If nothing else it would instill an idea of what it took to make things. One Of the shop teachers I had bucked the system and let us do some auto repair. It was before the regional tech schools were built. I put a new camshaft in a 57 Chevy in-line six. #5 cam lobe rounded. Seen several since then with the same problem . I also learned some rudimentary stuff about lathes that helped get me a job after my military tour.
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Golden Jubilee
Golden Jubilee

Posts: 4833

Joined: Thu Nov 29, 2012 11:47 am

Location: Bothell, Washington

Post Sun Sep 13, 2020 3:12 pm

Re: Head gasket

Dodge inserted sacrificial rods in the blocks, blogs on it in the Dodge groups
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Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sun Sep 13, 2020 3:49 pm

Re: Head gasket

I am not discounting sacrificial rods, to be effective they MUST be of different material than the item being protected. I use SCA in my coolant. It deposits a sacrificial layer on the liners of the engine to protect them
Iron rods in a cast iron piece are left over from the casting process, they provide no protection.
From a foundry manual ripped from the net
"Large or complicated cores need proper arbors or reinforcing rods in the sand to permit handling of the unbaked core and to help support the baked core in the mold"
Last edited by cornbinder89 on Sun Sep 13, 2020 4:18 pm, edited 1 time in total.

Golden Jubilee
Golden Jubilee

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Location: Canada's left Coast

Post Sun Sep 13, 2020 4:01 pm

Re: Head gasket

Here are two examples of castings. The grinder is a school shop project and the airfilter cover is a home shop casting. 433
Attachments
FILTER BRACKET 2.jpg
Home shop cast finned cover
DISC GRINDER TRUNIONS.jpg
DISC GRINDER.jpg
Shop class castings
I would rather have tools I do not need than to need tools I do not have
“Never argue with stupid people, they will drag you down to their level and then beat you with experience.
Mark Twain

Golden Jubilee
Golden Jubilee

Posts: 4575

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sun Sep 13, 2020 4:27 pm

Re: Head gasket

Casting is something I think we all take for granted, simple casts with no internal voids (coolant passages) are simple enough, but when it gets involved, it becomes a real art, and less of an "industrial process".
Even simple casts like a cast iron cook stove can be a work of art depending on the skill of the person making the molds.
I was discussing a 1906 "Glenwood" cook stove with someone who knew casting, his comment (he also had one of the stoves) was he had never seen such fine castings in his life, the finish was not machined from the rough casting, but was inherent to the cast itself.
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