MTFCA Forum

I soon will be sending out a block for cylinder boring and fitting of .030 oversize Aluminum pistons, the head gasket surface of the block is eroded at the front and rear coolant ports. what would be a safe material removal for cleaning up the deck, I am guessing .025-.030 or more may need to be milled away. The cylinder head will most likely need a skim cut on it's surface also. I figure the head bolts will need a shaving an equal amount of the total material removed from both castings. I do not want any interference with the pistons which are not high compression pieces.

Most shops only take off a few thousandths when they deck a block. Just enough to make it flat. I usually have them leave witness marks to show that a minimum was removed. I have had to have the area you are concerned about spray welded to build it up before the decking operation. I don’t like to cut the block down any more than necessary. 0.010” is a lot.

Not saying it's a good idea for your car, but my dad claimed to have had 1/16" taken off the block in his/my '25 Touring. No problems.

For deep pitting at the outer edge of the block, (not next to the bore), you might consider filling with hi-temp JB Weld, or even babbitt.

Jerry - I've been led to believe that you can take off more than that,....maybe as much as 0.080", but the trouble is, it's hard to determine if the head (or block) has ever been "shaved", "planed", or "milled" for any reason prior in it's nearly 100 year old life, right?

I have a reserve 1915 block in my shelves. It was badly eroded around the back water passage. I had a professional bronze the low area so that when the block is faced, the minimum can be removed and the bronzing cleaned up at the same time. I don't know for sure, but I think this bronze was added without any concerns for the bearings, not that that mattered with this spare, as they will be repoured anyway.

Allan from down under.

Hand brake any idea that any more than a light decking would be a good idea for a T block

T blocks have no wear lip in the bore for a reason, the top ring comes up flush with the deck on cast pistons and only a small fraction off TDC on aluminium ones.

Depending on make of piston, always check;

This photo shows the piston on the left that popped the ring out at TDC
.

I would be a little scared of brazing as the heat could crack the cast iron, but I suspect that someone who knows what they are doing could braze it.

You can determine how much has been taken off before by running the piston up to the top of the stroke and noting where it lands. You will have to temporally install a crank, one rod, and a piston. If you have a ridge in the cylinder that would tell you too. You could also measure a good block, deck to center of crank bearings, and compare that to your block. A rod mounted in place of the crank could be used for the measurement.

There are several metal filled epoxies available. One use for milling machine beds is Lab Metal, available on Amazon. The slow cure JB Weld is another. The surface has to be absolutely clean before adding any filler. Strong soap and water then bead blasting.

I guess it depend on what you are going to do with the engine. Are you planning on driving across the US or just down to the local ice cream shop?

Thank you Kerry for bringing this question up.
I was wishing to ask along the same lines and wondered why no-one... Ya know, "peanut gallery syndrome"...
Decking the block: Don't we need to be mindful of the top ring as it comes right up to the top?

The 'professionally rebuilt' engine (original) block in my '27 has brazed filler at the front and back water passages on the block. (Don't know who did it) It has seems to have held up fine.

I don't know if this works with brazing but when welding on cast iron using a nickle rod (stick welding) we used to hammer the weld to put it in compression. Because the weld was hot and cooled it was in tension which would lead to another crack along the weld, so hammering it changed it from being in tension to being in compression which took the tension away from the cast iron, which was the cause of the new crack.

Neil, the welder who arc welded my concrete mixer frame used nickel rods, and on every pass he hammered the weld as it cooled. Then another pass and the same. The weld ended up filling a void 1/2" deep and just as wide. It has held up now for some 40 years.

I have never done the same with bronze, or seen it done, but it does need to cool in its own time rather than being quenched.

Allan from down under.

Any kind of filler that can withstand 212F and almost zero pressure should work fine. No need for very heat intensive welding/brazing.

Kerry, In your photo the piston on the left looks to me like a Model A piston, I am unsure of the compression distance difference between the
A & T piston I know the wrist pin is larger in diameter on the A. The piston on the right looks more like the ones I have. Thanks for your reply. George

George.
Don't know the origin of the pistons but are T STD bore size and wrist pin size.
The engine was recon many years ago and left in storage, brought to me to check out to be used. What a mess it was never would have ran the way it was.

My block is out being bored for the new pistons, have put deck resurfacing on hold for now will check top ring exposure with crank, rod & piston in place when I bring home. Thanks for the responses. George