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You've got to be kidding! Pulling a flathead N? Well if you must, traction will indeed be your first problem as these machines were designed to be light weight and to hook up for plowing with the innovative draft control system. Can't use draft control when pulling. Aside from that, most of the hot rodding tricks used for flathead Ford V8s are adaptable as N engines used same bore/stroke as 239 Ford flathead V8 and some parts are interchangeable. Of course hot rodding a flathead is a lost art for the most part. However, as indicated by earlier post, late model Mercury flathead V8s were larger, 259 CI, if memory serves. So might be able to use Merc pistons w/o sleeves. As previous poster said you will need to increase compression ratio, and flatheads respond better to domed pistons, which were once available as aftermarket retrofit for Ns but I have not been able to find any for over 10 years, than to milling the head. Milling the head on a flathead reduces the transfer area between the valves and the bore limiting power at high RPMs. This is one of the fundamental reasons why all automotive designs and now even lawn mower designs have accepted the OHV design. If you are old enough, you might remember the 1961 or 62 Beach Boy's hit (one of my very favorite car songs) Little Deuce Coupe: "She's been ported and RELIEVED, she's been stroked and bored...." Relieving the block, i.e., grinding into the block between the side valves and the bore was the routine way of increasing transfer area to increase RPM capacity when using high compression heads on a flathead. Additionally, N engines were designed for 2100 RPMs max and have only three main bearings and a long stroke relative to the bore. The long bore/stroke ratio is good for a torque engine, i.e., industrial applications, but not good for high RPM applications. Nor are the three main bearing design and the small diameter rod and main bearing diameters. If you really want to pursue this and can compensate for the fundamental flathead defficiencies described above, you will need much more intake capacity. This can be improved by porting the block and intake manifold and installing a much bigger carburetor (stock 801 series??). Problem is: How much can one port the block without hitting water. Unlike Ford flathead V8s, which were commonly hot rodded and the experience base was well known, I know of no one who has attempted to do this with a 4 cylinder N engine. To gain substantial power, you will need much larger intake area and the N has siamesed intake ports (another inherent deficiency when compared to modern designs, but not one relative to most antique tractor designs). Experiment but plan to have several spare blocks on hand as did the innovators in the 30s and 40s. Having said all this, in the late 1960s I once saw a flathead Ford/Mercury powered dragster flat "blow away" a Chevy 409 (my very favorite classical muscle car engine) powered gas altered even after a substantial handicap for the short wheelbase altered. The flathead mounted the classical 3 Stromberg (97s) intake while the 409 was running Hilborn fuel injection. I was shocked. Clearly, those who knew how to do it could coax substantial power out of flathead engines but no one can overcome the inherent improvements of the OHV design. For what it's worth, I remain a commmitted 409/Z11 427 (betcha you have never heard of that) fan (absolute favorite car song is Beach Boy's 1962 hit 409). Nevertheless, the carbureted flathead powered dragster simply put the injected 409+ OHV altered on the trailer. Anyone remember the 50s phrase "flatheads forever?"
Dean
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