clevelend swap

Yeah, it sounds like you have a 400M (stands for modified Cleveland). Those blocks are taller than regular clevelands because they were designed to have a longer stroke. They have the Cleveland 2 Barrel heads which have stock over 2 inch intake valves and like 1.6? diameter exhaust valves stock. They have a weird lifter side oiling system that was notorious for being inadequate for oiling the top end in race applications (i had a 400M in a '78 F150 and it had tons of torque). Those engines don't like to rev since they're a "square" engine (4 inch bore, 4 inch stroke) but if you built one for up to like 6000 rpm it would rip in your car. People think they're boat anchors because in the 70's they did "quick emissions fixes" like retarding the camshaft (killed power), putting on tiny carburetors and single exhaust. Those engines were decent emissions engines, but when you stoke and engine or reduce it's bore to create better emissions more force is required to move the piston down and it sucks gas (mine got 11mpg no matter how i drove it). That's why most 70's V8 got bigger strokes (cheapest way to reduce emissions - more swirl entering combustion chamber, longer burn time due to faster piston speed (travels down a longer stroke)) That's why chevy came out with a 400 in the 70's and why ford debored the 302 to 255 in the early 80's. Chevy also debored the 305 to make like a 265 or something in the early 80's also but the engines were slugs. Anyways, i always feel defensive about these engines because they aren't all that bad, they just happens to have a $hitty compramised design goal. Another thing you grandpa may have done is taken a 351C and had a 400 crank machined to fit and a stroker kit, but that sounds unlikely given the circumstance. Good luck.

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'84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, more coming soon