Question on block water jacket holes

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Question on block water jacket holes

Post by Joe73 on Mon Mar 04, 2013 3:38 pm

Doing the final cleaning on my block and thread chasing everything. I'm looking at the tiny water jacket holes on the top edge of the block where the heads go on. I had small bolts in these holes when I removed the engine. I'm thinking of replacing them with pipe plugs with the allen key head. I know hole #4 in the pic if for a 1/2" pipe plug and is used to drain the block of coolant. I had petcocks installed in those but I'll be putting pipe plugs back in.

I'm concerned with #1, #2, and #3. These are tiny and I'm wondering if there is something better to close up the holes. Items 1 and 3 are only 1/4-20 threads. Hole #2 is 5/16-18.

The other side of the block only has the two 1/4-20 holes.

Maybe since they're so small, I should go with pipe plugs with the square protruding head as opposed to the allen key. All plugs will be going back in with some Indian Head sealant. I also threaded the (3) plugs above the cam on the front of the block. I'm still looking around locally for some "shallow" allen key pipe plugs for them.

Any opinions?

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Re: Question on block water jacket holes

Post by jerry46765 on Mon Mar 04, 2013 3:49 pm

1, 2, and 3 aren't supposed to go in the water jacket.

They are intended for heat shields, dip stick tube, and/or wire routing. If you don't use it, I would put a small hex head bolt in them and forget it until you have header clearance issues with the newly installed bolts.

What vintage is the block? Since the mid- seventies block I have in the shop has none of those holes and the '80s 350 block only has 1 & 2.

Thanks -
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Re: Question on block water jacket holes

Post by 77mali on Mon Mar 04, 2013 3:58 pm

The #4 looks like a drain plug hole for emptying the anti-freeze out. S/b one just like it on the other side. I have an 88 block and don't think I have anything like the ones you have numbered 1,2 & 3. (at least not spacing like that). I'll double check though as my engine is in my workshop, it'll be easy to look later on today. There are small holes above the exhaust ports for spark plug wire braces. i'm pretty sure Jerry is correct that they are not supposed to go all the way through to the coolant chambers.
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Re: Question on block water jacket holes

Post by Joe73 on Mon Mar 04, 2013 4:00 pm

The block is a 73 350 from my numbers matching SS. I did have small bolts in there and now I remember the heat shields. Those havent been on since the 80's. I forgot all about the shields. Its hollow in the holes so I figured it was the water jacket. I'll just put the bolts back in. Thanks for the reply.
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Re: Question on block water jacket holes

Post by pila on Mon Mar 04, 2013 4:42 pm

I'm just now bead blasting the heat shields for my '74 Malibu. I intend to rebuild the original numbers-matching engine & put it back in, with the stock items on it, like those heat shields. and original exh manifolds. Likely I'll sell it in the next few years.
Good to hear that you chased all the threaded holes in your block.
Don't forget to use a short bolt in the r/h lower front of the block, in that hole that intersects the fuel pump push-rod bore. As you likely know, it's oil leaker Very Happy

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Re: Question on block water jacket holes

Post by Joe73 on Mon Mar 04, 2013 5:02 pm

Yes, pila, I have that bolt. Good looking out. Well I just checked my bolt collection from the tear down. I did find that my garage is over run with lacquer thinner fumes. I found all the those small bolts, so I'm good to go. There soaking in some thinner as we speak. I want to install them before the final engine bath before painting.
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Re: Question on block water jacket holes

Post by 77mali on Mon Mar 04, 2013 6:27 pm

Don't forget the thread compound.
LOL

You better post build pics! Very Happy

I wish I had heat shields...I hate the "socks" on my plug wires Mad
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