flathead guru,s

I had to pull the flatty out of my coupe because the ring gear came of the flywheel.While it was out we took the sump off to take a look what it was like internally i knew from the reciepts that it came with. It had a full rebuild before i brought it.New crank rods pistons ect ect.Now the question i have is we noticed that the bottom of the pistons were machined to clear the crank.Im only guessing it has a larger crank would this mean it has been stroked to a larger cappacity. cheers scotty from oz

 

How close to the skirts come to the counter balance on the crank? it could be that they just put newer slipper skirt pistons in it.

 

Any pictures?
In some cases when balacing the pistons, they grind some off at the skirts edges!

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Taildragger&fenderless

 

Sorry, but I am more interested in the fact that the ring gear came off. I've never heard of that before.

But, on your stroke question, no bid deal to pull the heads while it is out to measure the stroke from there, is it?

 

Ring gears can and do fall off. When installed correctly, three spots of weld will hold them on. Look at the paper work to see if the bore and stroke were recorded. Otherwise, the only way to know what you have is to remove a head and measure. If you are very careful, you may be able to measure from the bottom if you have snap gauges.

 

You should be able to measure the stroke from the bottom; bottom of piston skirt to bottom of cylinder, at bottom and top of stroke. Or even from pan rail to big end of rod; horizontally back and forth.

 

Here is a pic of the ring gear.sorry no pics of the skirts on the pistons had some mates helping so we got it back together and put straight back in

 

If the ring gear was installed cold there's a good chance it will come off, if it is heated to approx 300-350 degrees (expanded from the heat) and installed and allowed to cool it should be ok as long that the flywheel is not damaged where the ring gear sits, I have been doing this with Diesel engines for over 30 yrs and never had a problem, also do it to all of my engines, the ring gear is interference fit, and should never be hammered on

 

Here it is back on.we heated it up

 

It looks like it was heated with a torch ?

 

We used a oxy

 

That's how you install a new ring gear. Heat it up evenly passing the OA torch (w/a neutral flame) around and round the perimiter of the ring gear expanding it. After it gets good and hot you slip it on the flywheel while it's expanded and let it cool, shrinking to a press fit.

Frank

 

what if you put it on backwards?