1949 to 1953 flathead crack block

[1931flathead]

went and got my flathead today found a crack between the intake valve and cylinder wall the some valve were stuck but not the cylinders they are good

the question that I have should I go and look for a another block or the shop says he can fix it what would you guys do

i'm putting in a 4 1/4 crank and bore is 3.375

[Ken/Alabama]

If the end of the crack can be pinned inside the intake valve pocket then a sleeve can be put in the cylinder you'll be fine.

[1931flathead]

I was going finish tearing apart and taking it into him to see what he says I don't want to spend whole bunch of money and don't work out

[petes 50 merc]

i took in 12 blocks before i found a good one . been in my merc for 10 years ive never had a problem .

[Ronnie]

Should be able to pin it but a picture is worth a thousand words.

R

[1931flathead]

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it is hard to see it is that small will try to get one

[29AVEE8]

Pressure test and magna flux before a machine tool touches it, there may be more.

[1931flathead]

here couple pic

[1931flathead]

I will look to marrow to see how far it go into the seat and cylinder wall

[1931flathead]

Will try to get better pic on saturday

[flatheadmurre]

That crack doesnt look to bad.
If it doesnt go deep into the valve pocket i would use the block.
Right now with carbon deposits it will probably test fine in a pressure test.

[big job]

Somewhere on utube there is a shop repairing the same crack only worse than
yours. Good info there not that hard to do.

[saltracer]

at 3 3/8 I would definitely sonic test the block before doing anything else. Just got back from the machine shop with my block, did all the other work and then bored.........two cylinders have what appears to be break through from the inside out like rust pits. I now have a sonic tester and find the walls were .050 thick in this area.

[Init1]

The good news is that crack in your pics can be repaired. The bad news is there might be more.
Check that block every way you can including the exhaust tubes inside the block.

[gobel]

I don't know your location, had worse cracks.
I had them repaired at j&m engines in southboro,ma

[GOSFAST]

Originally Posted by 1931flathead

went and got my flathead today found a crack between the intake valve and cylinder wall the some valve were stuck but not the cylinders they are good

the question that I have should I go and look for a another block or the shop says he can fix it what would you guys do

i'm putting in a 4 1/4 crank and bore is 3.375

I don't believe you will be able to finish the bores at your desired size with a sleeve in the program.

Have never tried that size here before with a sleeve. Have done the 3.312" though with it!

Thanks, Gary in N.Y.

P.S. You may get by with the "stitching" procedure, we just did 2 blocks (not Flatheads) and they worked out fine after coming off the dyno!! Takes a little time & patience but is doable. Below is a shot of one recently stitched, if you look closely you can see the plugs.

[Bored&Stroked]

The tried and true 'Lock n' Stitch' process should work fine with that crack, but you'll need a sleeve. To ask the obvious question, why are you going to 3 3/8? Even if you get by with that level of bore, you've effectively reduced the engine life for the future - as you'll probably not be able to bore it again. Unless you are all-out Bonneville racing, I'd take just a bit more conservative approach and go to 3 5/16 . . . will result in an engine that is just 12 cubes less than 3 3/8 bore (with a 4 1/8" stroke). No reason to bore these blocks out to the max - is just too hard, expensive and time consuming to find good blocks. So there yah go . . . just another opinion to ponder.

As others noted - have everything in the block checked before investing in machine work. Also, if it was mine - I'd have this crack and cylinder done FIRST, pressure tested and then I'd do the rest of the block.

[rotorwrench]

If that block has hardened seats, the crack may extend under the seat. If it does, the seat will have to come out to check how far it goes. It would have to come out anyway in order to pin it if it's worth the trouble. The later 8BA type blocks had hardened seats in the exhaust only and the last of the series had no hardened seats at all unless they were for trucks. The previous posters are right about pressure testing with the soapy suds. You may find more cracks in other places. The sonic testing is likely the most important for a big bore candidate.

[1931flathead]

well thanks for the help guys went and clean it up better today the crack in the pic is the only one I seen but there are two between the water jackets and the bolt holes on one side but never looked on the other side I gave up when I seen a lifter bore had a crack down it

so my friend had a 59 block that he got and starting down I had to nock out 6 pistons and rods and remove the head studs did not find any cracks taking to the shop on Monday after dinner have him check for cracks and tank it if good I will get it sonic tested and pressure tested

I got my crank and got a super deal on my pistons

the car will not get run very much up in minn we don't have much good weather if it would get 2000 miles a year would be lucky

[1931flathead]

took my 59 block in and had it check and found 3 cracks between the bolt hole and water jacket

should I fix the block or leave as is my crank is 4 1/4 bore is 3.312