Merc block w/small crack between valve and cyl??

Jack 34pu

Jack 34pu

Senior Member
Well, the machine shop has had my block for months and finally got around to start the machining. They magna fluxed it when I first took it in and gave me the green light. They took .008 off the decks to clean up some pitting and did rough bore for .080 pistons. Now a small crack (1/2" or less showed up between a valve and cyl. They want to check it further but suggested pins and a sleave. I'm already into this build - shoud I keep going?
 
Pressure test the block... I would also consider welding the crack and not sleeving it... Pin and sleeve is ok, would be my second choice... Karl
 
I can see how that kind of surprize kinda sux. If they would have found the crack before putting all the machine work so far in, you could have maybe come up with another block. I haven't had much luck with welding the cast iron especially on L-head blocks in or near the valve pockets. It usually cracks again right along the weld area if it ever even gets a little hot. Lock & Stitch pinning is what most machine shops recommend and it works if done properly. Going into the cylinder wall will require a sleeve though. Sleeves are not a bad thing just expensive. They will have to match the sleeve to your other bores too. That just really sux!

Better luck next go-round
Kerby
 
At this point you need to make sure this is the only problem. Frank Casey in Millbury Ma is a master at stitching these blocks. About 350 miles from Hershey.
 
Jack,
Ouch.....welding that crack is nearly a lost art....I'm quite sure someone
knows of a welder up to that task. Pinning/stitching is closer to my comfort level
due to subsequent machining that will be required.
Hershey ? We're at RCB 49/50...we owe you and Sherry an ice cream treat at
Hershey World.
Charlie ny
 
Ther's a guy up north of me, used to have a bussiness in Oakland, Ca. called excellsweld... Preheat the block, weld, back in oven to cool for 24 hours, requires new seat in the one hole... Happy to look up the name if anyone wants... Karl
 
Just make sure the crack don't go down the port under the valve to far, it's hard to pin or stich what ever you want to call it down the port. Pin it across the block and sleeve the cyl. No problem. Walt
 
I'd press the guy for a deal on the stitch and sleeve, since he's the one that missed it and put you in this position. That being said, I think it is a reasonable expense to end up with a good block. Even if I knew in advance about that problem, I'd go ahead and do it.
 
Merc Block?

It may matter a bit whether you're talking about a pre-war or post block since later Merc blocks are not unique to Merc and worth somewhat less. Not good business to pour hundreds into a $50 block. I had a couple of extra blocks inspected at some expense and after finding them uncracked and sound with exception of some deep rust in one hole each, had to take $350 each. The inspection and the acid dip cost half of that amount. Good Luck: Fred A
 
Would a block necessarily have to be 'fixed' if the crack doesn't touch the valve seat yet and is at the very top of the cylinder (above the top ring)? We took a running engine out of a pickup and found a crack between a cylinder and valve as I have described. We're wondering about just running it (in a different vehicle) for as long as it will run. If the crack hits the seat or runs further down the cylinder wall, yeah, that will have to be fixed. Wondering if we can milk some more miles out of that motor without an expensive repair bill.
 
Frank Casey of Mass Is the guy to do your stitching. If the crack doesn't run down the cylinder more than an inch or so you don't need to sleeve it
 
southfork said:
Would a block necessarily have to be 'fixed' if the crack doesn't touch the valve seat yet and is at the very top of the cylinder (above the top ring)?
Click to expand...

You raise a good point. Many engines that seem to suffer no ills and run fine are found to have cracks when inspected. Clearly, not all need a repair.
 
I'm wondering how come the Shop didn't find the crack when they Magna Fluxed it. That's why they do it before they start any machine work!...
 
It was magnafluxed before machining started. I visually checked the block myself very carefully but this small crack showed up after initial machining. They are going to mag it again but it didn't appear to go into the valve seat area - close but not there.

Hey Chuck, have your blocks been cleaned and magnafluxed? This is a 50 Merc although I think Ford & Merc blocks were the same.
 
I agree with old Ron. Stop reinventing the wheel put a few stitches in it and carry on.I have done many stitches myself it is not rocket science real easy to do.Welding cast iron is a crap shoot at best for the average shop to perform. Can it be welded yes it can but ask for a guarantee and see what you hear. There are hundreds of stitched blocks still running out there. Google cast iron stitching and see.

Ronnie
 
My shop showed me the threaded pins that go in. Inverted threads that flatten out to seal. My concern is that you are putting more pressure to separate the crack. If you don't get to the bottom, wouldn't that be more stress on the crack especially when the block gets hot?
 
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