| Steve S | -- 03-09-2010 @ 6:32 PM |
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On my '52 Merc engine one head stud hole (left side, top/center) has no threads whatsoever. The hole isn't even straight into the block. I'm guessing that there used to be threads here since the hole on the opposite side has them like all the others. I also assume that I can't run the engine without this stud in place. Is there anything that can be done to fix this problem? Photo attached...
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| 42wagon | -- 03-10-2010 @ 3:40 AM |
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I'm going to guess that someone broke a stud and then botched the job of drilling it out. I think any machine shop can redrill and rethread the hole using an enlarged stud or a helicoil. However before you go to that trouble you should check to see if there aren't other problems with that block that make it a boat anchor instead of a rebuildable engine.
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| supereal | -- 03-10-2010 @ 7:39 AM |
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We see many bad threads in old cast iron blocks at our machine shop. In most cases, they can be Heli-coiled if the hole hasn't been "wallowed" out by drilling, etc. In that case, we make studs with over sized ends for the block side. This is important, as many studs are "wet" as they extend into the water jacket. In any case, studs must be well sealed when reinstalled. Old cast iron can be very fragile, and if you "chase" the threads, be sure to use a tap for that purpose, not a common threading tap, or you will likely have a number of places where torquing will pull out the threads.
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| Steve S | -- 03-10-2010 @ 9:02 AM |
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Thanks for the info. Any idea how thin that water jacket is, or how big I can go with the threads? The hole is definitely wallowed out a bit.
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| TomO | -- 03-10-2010 @ 9:37 AM |
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Steve, your block uses bolts instead of studs, therefore you should keep the thread size the same using a helicoil or an insert. Use the hole on the other bank for depth reference. Tom
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| supereal | -- 03-10-2010 @ 12:32 PM |
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Given the amount of "core shift", it is impossible to know the thickness of any part of the block. That is what makes cylinder boring "interesting". On the 8BA or 8CM blocks, we use ARP locking head fasteners to secure the heads on old cast iron blocks.
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| Steve S | -- 03-10-2010 @ 8:26 PM |
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I guess that leads me to another question. Since this engine is in a '39 pickup, I was thinking of using studs instead of bolts to make it look more correct. This would also allow me to change thread size on the one hole if necessary. Would using studs be a bad idea?
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| 37RAGTOPMAN | -- 03-11-2010 @ 7:24 AM |
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hi you could use a old head,for alignment,then by using a sleeve inside the head stud hole,and a undersize drill that just fits inside the sleeve you could straighten out the hole and work you way up, by using a few different sleeves,and then helicoil the hole,this so you could install a new head stud, you , its worth a try if you have some mechanical knowledge,or you could farm it out,go to a good machine shop,you might be able to trailer the truck to one and have it done, it would save pulling the engine, there seems like some rust on the cylinder walls, this should be removed wiht a cylinder hone, use it very lighthly. do before you start the engine, let hear how you made out,!!!!!!!! my 3 cents 37RAGTOPMAN
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| Steve S | -- 03-11-2010 @ 8:16 AM |
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Thank you sir! The engine is already out so that isn't a problem. I don't trust myself to perform such a task so I will haul it to a machine shop.
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| alanwoodieman | -- 03-11-2010 @ 9:33 AM |
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use studs,unless you are going for points, in these old blocks the cast iron has been thru so many heat cyles the less you "use" the block threads the better
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| supereal | -- 03-11-2010 @ 9:49 AM |
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You can use studs instead of head bolts, but the simple solution is to use the bolts and put acorn caps on them.
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| Steve S | -- 03-11-2010 @ 10:05 AM |
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Interesting idea, I hadn't thought of acorn caps. Since I'm planning to replace all the bolts anyway, I'll probably just go with studs though. Four of the old bolts were broken off in the block so I'm not planning to use them again!
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| Stroker | -- 03-11-2010 @ 1:15 PM |
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ACORN COVERS! IMHO that would be like installing fake wire wheel covers, or the fake chromed Cadillac tail fins they used to put on 49 Chevys. Studs have an advantage over the 49-53 capscrews (bolts). You are not relying upon the thread interface in the block casting during cylinder head torquing, as the SAE (NF) thread pitch on the nuts gives more control over clamping pressure. Good studs are manufactured with rolled threads. I suspect that Ford switched from studs to capscrews mainly to control material and labor costs. If one really want to make it bulletproof, consider Helicoiling all of the holes, and installing good quality ARP studs.
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| 37RAGTOPMAN | -- 03-11-2010 @ 4:37 PM |
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I have a 49 53 MERC engine if you need one, JUST IN CASE I am in MID COAST MAINE 37RAGTOPMAN
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| Steve S | -- 03-11-2010 @ 5:00 PM |
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Hopefully it doesn't come to that, but heck if the price is right then I'll buy yours, and save the money on taking a gamble with getting this one running!
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