Bore and piston measurements

Oh well, that's gone and done it now! Went to take the valves out of the head, decided to chip a bit of flaky rust off the inside of the exhaust port with my screwdriver, and it went through the casting and into the water jacket! That's what kills all these engines off in the end. You can't get cylinder heads for them. Not sure what I'm going to do now, but piston rings are the least of my worries! At present, the holes is about 1/4" across in a vaguely cylindrical cast iron duct. I could reach it with a die grinder, I think. I was wondering about trying to clean it back to bare iron and then maybe brazing a plate over the hole?
 
Avocet said:
Oh well, that's gone and done it now! Went to take the valves out of the head, decided to chip a bit of flaky rust off the inside of the exhaust port with my screwdriver, and it went through the casting and into the water jacket! That's what kills all these engines off in the end. You can't get cylinder heads for them. Not sure what I'm going to do now, but piston rings are the least of my worries! At present, the holes is about 1/4" across in a vaguely cylindrical cast iron duct. I could reach it with a die grinder, I think. I was wondering about trying to clean it back to bare iron and then maybe brazing a plate over the hole?
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See my post on the other thread.
Going on. My experience with old cast iron and a torch is that it ends up crumbling.
S
 
I just thought I'd resurrect this thread after a season's use, in case anyone is considering a similar course of action. I used the three-legged honing tool in the drill, with kerosene as a lubricant. I was fairly aggressive with it (maybe a total of 30 seconds on the (mains-powered) drill's highest speed, in about 10 second bursts with a swill-out with clean kerosene and a check in between each 10 second session). Made sure to keep it moving up and down the bore while it was spinning, and only let about the top or bottom 25% of the stone poke beyond the top or bottom of the cylinder on each stroke.

New rings fitted. Bore was still well within wear tolerance after the operation (in fact, a barely measurable increase in diameter). Fine "scratches" (bit too fine to call "cross hatching", I think!) were visible afterwards.

I'm delighted to report that it has used no oil over this season and that my transom is now as clean as the next man's! Thanks all!
 
Excellent result.

What did you do about the hole in the head? In the mid 1980s I completely wrecked a VW diesel engine, con-rod through the crankcase wall and plenty other damage. The head was cracked quite badly, but living in Aberdeen at the time I used the Aberdeen Head Shop http://www.torryegarage.co.uk/about-us/18-aberdeen-headshop.html to repair it. They carry out weld repairs in cast iron at red heat, which is really the only way that CI can be welded. Very successful repair.
 
Ah, a good forumite happened to spot a second hand one on eBay (in Australia of all places)! It turned out that it was off an engine in a boat that had been laid up in 1987 and when recommissioned, the seals on the raw water pump had gone hard, and had allowed seawater into the crankcase, destroying the rest of the engine. The result was that the head was in excellent condition as far as corrosion was concerned. I don't think my old one (although I still have it) could have been welded as the hole was in a very inaccessible place (from inside the water jacket to inside the exhaust port)
 
skipper_stu said:
See my post on the other thread.
Going on. My experience with old cast iron and a torch is that it ends up crumbling.
S
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In my previous life as a Classic and Vintage Motorcycle specialist I have welded plenty of cast iron cylinders and heads. Fixing broken cooling fins was a common job for us. Plain old fashioned gas welding worked for heavy castings using normal welding rod for non loadbearing areas. Low tempreture bronze welding using nickel-bronze rod and borax flux worked well for fin replacement.

I once saved a veteran-about 1913- Vee-Twin Precision engine that had had all the fins chiseled off the one piece heads and cylinders and-I kid you not-buckets welded to them for crude water cooling when used as a power plant of a saw bench.

IIRC I made and fixed 120 sheet steel fins to the cylinder/head units.

The motorcycle was a runner when finished and is one of only a few still existing.

It is however a very tricky job and not to be undertaken lightly-for the very reason you state.
 
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rotrax said:
I once saved a veteran-about 1913- Vee-Twin Precision engine that had had all the fins chiseled off the one piece heads and cylinders and-I kid you not-buckets welded to them for crude water cooling when used as a power plant of a saw bench.

IIRC I made and fixed 120 sheet steel fins to the cylinder/head units.
Click to expand...

I salute you, in awe. No kidding.
 
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