Cylinder and piston wear

Posted by Ken_P On 2014/9/30 21:25:39

Hello all. I'm in the middle of trying to overhaul my engine. I wanted to freshen it up now, before I delve into body work. The block is cracked so I trying to freshen it up and reduce the haze of blue smoke that comes out of it whenever it runs. Prior to the teardown, my compression was 95-85 psig on all cylinders, but it smoked (blue) no matter engine temperature. I only put maybe 20 or 30 miles on it, so I can't tell you if it was burning significant oil.

I have two questions.

1. I measure the cylinders for taper, and as far as I can tell, all of my cylinders are 3.440" (+/- 0.002") in the middle and bottom of the cylinder. Top of the cylinder, just below the carbon ring, seems to be 3.450", +/- 0.002". It is my first time trying to take these measurements, but I took all of them twice, and it seemed pretty consistent, so I think I am doing it close to right. What is the specification for cylinder taper? I cannot find it for this engine. I am not terribly confident in my measurements because it is the first time I've ever done it. The cylinders were clean and dry, but I haven't run a ridge reamer through it yet. My upper measurements were just under the carbon ridge.

2. Two of my pistons are slightly damaged. Should I replace them? See pictures below. Also, anyone have a source for NOS pistons? (No, flackmaster doesn't have any!). One is marked D and one C, so one is 0.0015" over and the other is 0.001" over stock size. The other four pistons are flat.

Thanks!

(Many more pictures in my project blog)

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