B with domed pistons

Davset · Feb 9, 2010

I just bought a "47 B that, I"m told, has doomed pistons in it.
Were these a normal factory option?
How much more power do these provide over standard flat-topped pistons?

Janicholson · Feb 9, 2010

High altitude pistons were available in several different compression ratios (based on altitude. 8000 ft pistons were the highest dome.
Many after market pistons were also domed. It is a good deal, as compression increase can make the engine substantially more powerful on the same (modern) gasoline. Jim

Jeff Z. · Feb 9, 2010

Yes, Probably a high altitude engine.
I do not know how much they increased the compression.
Your serial number may have some letters after it that will show high altitude.

Red Dave · Feb 9, 2010

It may have come from the factory with some kind of high altitude kit in it, or more likely somebody rebuilt it over the past 60 or so years and put Firecrater (IH Brand of high topped pistons) or some other brand of high topped pistons in it, I would not be surprised if they are also oversized, as that is very common on a rebuild.

I rebuilt my B using high compression, oversize, pistons. Oversize is using 3 1/8" diameter instead of the stock 3". Very easy to do, they just use a thinner wall liner. I also had the head planed a little to make it flat.

I got 135 lbs compression after the rebuild, and it dyno'ed at 24 horsepower. Didn't change anything else, running only 100 RPM's over stock.

It's got more power than traction at this point.

Brown Dirt Cowboy · Feb 9, 2010

Red Dave when I rebuilt my B several yrs ago for pulling I went to 3 1/4 oversize and put the head from a 133CI motor and up the RPM's to 2100 and it dyno'ed at 33HP on the PTO. Add another 1000lbs of weight that will take care of the traction problem.LOL Haven't pulled the B in a couple of yrs now. But I do enjoy taking it and the 1-16" Little Genuis plow to plowday.

Red Dave · Feb 9, 2010

yea, I could get more out of it, but I'm not a puller. I'd rather keep it closer to original RPM's. Less chance of breaking things.

It does pull a plow very nicely. We have a lot of rocks and the wheel slippage keeps from busting up the plow too.

gene bender · Feb 9, 2010

Only way to find out what pistons you have is remove the head and take some measurements as there are many types of hi=domed pistons that are available.

Brown Dirt Cowboy · Feb 9, 2010

I don't carry all the weghts now that I did when I was pulling the B. One set of wheel weights and one suitcase hung on the front. Seems like the frontend is awful light on the B. It does pull a plow real good.

B with domed pistons

Davset

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Janicholson

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Jeff Z.

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Red Dave

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Brown Dirt Cowboy

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Red Dave

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gene bender

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Brown Dirt Cowboy

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