C69A block

[Lawrie]

Bad luck on the C69A block I'm doing for a spare,
I had sonic tested all wall thicknesses and they looked great, bored three bores good, started cyl 7 and got it nearly to size and it had three or four large areas of porous type spots , tried shifting the boring bar around but they were too deep, Dam, as this block had nice valve seats and faces.
So its back under the bench and will look out another 99a block to start again,
Good job I can do this myself.
Lawrie

[Brian]

Yeah Lawrie, I feel for you...been there, done that. had a C69A block, std bore, great valve seats, didn't even have the part number cracks, sonic tested real good...boring to 3 5/16...on the 4th hole we found a pinhole that went through to water jacket. Had to sleeve it back to std. I have had other C69A's where, whilst porting them get into this black, soft [carbon] type material that just seems to be randomly placed throughout the casting. Whilst those 69's have real thick cylinder walls, they are definitely cast in an inferior iron to the pre war blocks. Good luck with the 99

[JWL]

This is the reason, as I explained in my book, that a proper sonic examination can NOT be done in a matter of a few minutes. The cylinder bore must be probed in a grid pattern, with small increments, to be reasonably sure a bore will accept a significant overbore. It would not be unusual to require an hour to check one cylinder if thorough information is necessary. The area of measurement during a sonic micrometer reading is very small, similar to a standard thimble micrometer.


I feel your pain and wonder if a sleeve might solve the problem? However, there is always the specter of other, yet to be unmasked, problem cylinders.
JWL

[JSeery]

That's what I was thinking, a sleeve in that cylinder?

[tubman]

Perhaps unrelated, but this same thing happened to me on the last 8BA I built. When going to 3 5/16", a pinhole was revealed in one of the cylinders. After a phone call, the decision was made to sleeve that cylinder for an extra $100, and the job continued. No problems and the engine is just fine.

Is there some other concern? This seems simple to me.

[Bored&Stroked]

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I'd bore the rest of the block and then you'd know if you only need one sleeve or more. I'd also pressure test it after boring - as sometimes there are issues you "can't see".

[Lawrie]

JWL, I spent a fair bit of time making up a sheet for each cyl, and then went to work with the sonic tester, this showed a problem on that side of a mostly .280 wall thickness but a small area with .200 wall,I checked about 16 spots in each bore , so I was aware this one had a problem and had noticed an intermittent cut on the borer,I also took a lighter cut and removed the borer and rechecked the thickness on the thin area,
wife Carol is more concerned than me.
I will label the block and park it back under the bench and get out another.
This block also had what looked like score wire still in the inside of the bore when I looked closer after boring it,
the engine was only a long term spare for the 33 ,which is going like a train so no worries.
Lawrie

[Lawrie]

Looks like the block will be saved, I bored the crook cyl out for a liner,Its now about.020 under the liner OD ,I will finish size it when the liner arrives.
Interference on the liner..0015 - .002 or .002-.003, thoughts, I will dry ice the liner down before installing it.
I took nearly out to the OD of the liner to get rid of the porous casting on that cyl.
Lawrie

[JSeery]

Always good news to be able to save a block!

[KiWinUS]

Lawrie my great friend second daddy with machine shop installs multiple sleeves each week to include flathead said.0015 city. .125 up from bottom is step. Doing this for a living over 66 years I believe what ever he suggests to me. Cheers
Tony

[Lawrie]

Thanks Tony,
I was happy to see the liner will fix up the block, as like I said it has great valve seats and every thing else,
Looks like the crook cylinder was the reason it was layed up,
this is the first time I have fitted a liner ,so my boring bar does a great job,I have a couple of other engines in my stash, one a 36 that the reconditioner buggered a lot of years back and has one thin bore, so I will look at fixing it as well.
Take care and stay away from the Virus, looks like we here(QLD) can now travel freely to all other states and NZ.
Lawrie
Lawrie

[KiWinUS]

Fantastic. Too bad you don’t have a NOS crank ��

[Lawrie]

Next time your back to NZ,you could drop one off on the way.it willl go well with the nos rods and bearings.LOL.
Lawrie

[38 coupe]

I don't know why folks get worked up about sleeving a hole. In the past two years I have helped rebuild two motors, and we installed four sleeves between them. It is a bit tedious, but not particularly difficult or risky.

[Lawrie]

Well, today I bored the other cylinders in the block.I had done a cleanup bore on all the bores the other day so I knew they were all thick enough.
BUT, as Brian says casting is nowhere a nice as the model A or early V8s,lots of the same funny brown spots and areas as the one that I bored for the sleeve,so far have only two more to bore to the size(3.3125) , but the borer cuts through hard spots and brown spots Ok,
I thought about sleeving them all as the sleeves are not that expensive and my labour is free.
will make a call when the other two holes are done.
Lawrie
Lawrie

[Rudolph]

Was that from rust or the use of the crappy spots in the iron?

[Lawrie]

It was crap spots and stuff in the casting
Lawrie

[Rudolph]

The 1938 24 stud engine in my car now has that around cylinder #1, it caused a stud to pull out and I had to help coil the thread

[38 coupe]

That is not a confidence inspiring bore. I think I'd sleeve all holes so you know you have good consistent cast iron bores to seal your rings. The sleeves I have finish bored were harder than the 8BA blocks we installed them in.