Surfacing the top of a block.....?

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Model T Ford Forum: Forum 2017: Surfacing the top of a block.....?
Top of pagePrevious messageNext messageBottom of page Link to this message  By George Andreasen on Sunday, November 12, 2017 - 08:36 pm:

I have a 1918 block that I'm rebuilding, mostly because the Babbitt is still serviceable...and it's the only one I've got. I've cleaned it thoroughly and reamed the valve guides to accept Chevrolet 350 valves (I have valve inserts that will be installed). In addition it will be bored to .060" oversize. Incredibly, the crank mikes at standard and is round!

There is pitting in the area of a couple of the valve seats, although the seats are still good. Most of the pitting is moderate, but there's a couple of deep ones, maybe .020" or so. When I take this in to the rebuilder, I'm almost sure he will suggest resurfacing the top of the block. If I recall, the top piston ring in a T engine comes all the way to the top. Just how much material can be removed from the top of the block safely?

Frankly, about the only thing that can happen is for carbon to get trapped in the pits, so maybe I should just leave them and not worry about it?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Sunday, November 12, 2017 - 11:53 pm:

George,
Aluminium pistons don't bring the top ring to deck height like the original cast ones do.
Fit inserts first, deck the block and then bore.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Monday, November 13, 2017 - 02:01 am:

George, the block will most likely be decked to level up the valve inserts, so cleaning it up should be taken care of.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Andreasen on Monday, November 13, 2017 - 07:33 am:

Thanks guys......now I won't worry as much!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Monday, November 13, 2017 - 08:45 am:

Make sure the rebuilder doesn't dip the block in his usual cleaning vat - that could destroy your babbitt.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Monday, November 13, 2017 - 10:03 am:

Check your crank's not bowed. I've seen cranks with perfect journals that "ran out" over .003" on the center main.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Andreasen on Monday, November 13, 2017 - 11:32 am:

I've already got the block pretty clean, but it the rebuilder insists on hot tanking I will insist that it be done upside down and just to the depth of the water jackets.

I put the crank between centers on my lathe and checked it with a dial indicator. Zero run out.

I think this engine was rebuilt not long before the car itself was junked. The pistons were .040" oversize and all the bearing surfaces look too good for an average T engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Monday, November 13, 2017 - 03:09 pm:

Here's a question - when we found my bowed crank, it was checked with V-blocks on the end journals. Is a test for "straight" the same thing with a crank spun on lathe centers ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Monday, November 13, 2017 - 03:24 pm:

V blocks is the right way, a lathe can give a false reading.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Monday, November 13, 2017 - 03:28 pm:

Kinda what I figured. I wouldn't want George to join the "2-piece Crankshaft Club" !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Monday, November 13, 2017 - 04:28 pm:

George, you may not need to worry about the hot tank issue. Depending on the chemicals, whitemetal will ruin the mix and deposit a grey coating over anything in the tank. Your machinist is most likely aware of this, and will not put your block in the tank. However, it won't hurt to remind him.

I had this experience once. I had been instructed to remove the bearings from the block before my machine shop would do the work. Two or three of the little plugs of whitemetal in the locating holes on the main bearing journals was enough to put a light coating on the block and a few other T parts. Fortunately, it was not enough to kill the tank chemical mix.

Hope this helps.
Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By john kuehn on Monday, November 13, 2017 - 04:29 pm:

You can clean up a block without hot tanking it. Clean it up the best that you can and you will OK.

Use some mineral spirits to remove any grease and etc. Clean out the water jackets using a speedometer cable to break out any scale.

Carefully drill out the holes in the block and also the head with a 1/4 " drill.


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