N Mystery Engine

Internally, everything seems to be standard equipment except the 4 ring pistons and camshaft. I searched high & low for part numbers on the cam, 9N is all I can find and a B on the dist drive. Comparing it to the factory "NC 6250" cam, the exhaust lobes seem to be the same but the intake lobes have slightly less lift and a much different profile, less duration. Doesn't show much ware, real crisp, pointy lobes.

Anyone have any ideas on the intended application of this engine? Also, looking for opinions on the 4 ring pistons, good or bad? Thanks for any input

Thanks for your insight, especially on 3 vs 4 ring pistons, much appreciated. Guess it's not really much of a mystery engine, more likely a "remanufactured" long block some outfit produced.

Did you read my reply to "longbowsteve" 7-posts down the page???

"would it surprize you to learn Ford sold the 9N engine for industrial purposes such as remote electric light generators; irrigation well pumps; railroad refrigeration cars; air conditioning for Pullman RR cars; haybalers and threshers;

And surprisingly enuff was used for early WW2-Jeep engines because Willys was "swamped" with Gov't Jeep orders. (wonder why?) Infact the 4-cyl N-Engine was also sold/installed by Ford in city delivery coupes and pickups, principally for gas economy. In vehicular use, its rated at 43hp? at 3500rpms, while the tractor rating for the same engine is 23hp at max governed 2200rpms.

And all N-Engines have a cast-in "boss" on lower left frontside for camshaft operated fuel pump. Yer N-Tractor has NO fuelpump, but is gravity fed. Except for the fuelpump application, there is NO DIFFERENCE internally between the N-Tractor engine and industrial versions. (that I know about) Some may have down-draft carbs instead of up-draft carbs.

Its not unusual for N-Engines to get swapped around because they all fit."

As for the 4 vs 3 ring pistons. Gitt the 3-ring replacements. Why? 'cuz the 4th-ring is too good. It was an attempt to reduce oil burning and worked too good removing oil (it is an oil ring) and caused more and faster cylinder-wall wear and reduced compression, thereby causing faster and more frequent engine rebuilds.

In some DUSTY tractor applications (caused by frequent mechanical weed control between rows) it was not unusual to rebuild N-Tractor engines every winter.

The 3-ring piston actually has 5-rings. The oil-control is 3-rings, 2-skinnythin scraper-rings separated by wiggly expander ring. Modern piston rings are so much better. Don't get the "chrome" rings, they take TOO-LONG to seat and develop good compression seal. Yer 6:1 compression flathead needs all the help it can gitt. The replacement flathead is 6.5:1 compression introduced with the 8N.

Check yer current flathead for "warp" and previous signs of "milling" the head for compression increase. You can mill the flathead just 1-time before the valves start bumping the head.

Oh yeah, replace yer dry-sleeves, some hot-rodding techniques removed the sleeves for a "big-bore" increase using early Mercury-V8 pistons. Iff'n they are "missing" sleeves, use the "improved" 0.090 thickwall castiron sleeve which means you will have to have the block re-bored. (a standard machineshop procedure)..... .Dell