Hey! I just happen to be hacking on Rambler 195.6 OHV's now. I'm an inliners member, just signed up to the forum yesterday.
I can tell you some stuff about that motor. I've built a half dozen motors, only one mild performance, but I'm otherwise a decent wrench.
I like this motor, but I'm not blind to it's downsides.
The 195.6 OHV (there's a flathead version) is a brick sh*thouse of a motor. Crank and rods ARE forged. It's only 4 main bearings, but if you even glance at the bottom end, it's insanely overbuilt. That's not a weak point.
I can state with some confidence that the alleged reliability problems with this motor are 100% maintenance. They're all old; they were in economy cars; it was an old design in the era of V8's; therefore none of them got treated well; and everyone "hates" Ramblers.
It needs head retorquing on a regular basis which no one did and surprise, leaks and cracked heads.
The head is the weak point from a performance POV. It's a cast-in, trough-style intake (sound familiar?). The exhaust travels a fair distance through the head, transferring a lot of heat. Valves are small, but not crazy small. The ports don't seem too badly small or twisty otherwise. A turbo would solve the intake side problems, but might worsen the exhaust heat issue. But I'm a bit conservative and no expert.
It's a partial-flow oiling system; there is a full-flow filter oil pump for 65? that bolts on, but it hits the chassis on eary Rambler AMericans. HOWEVER I have a junk pump here and worked out that simply drilling the pump side for two AN fittings would easily allow a "remote" filter to fit in. Oil pump is external. I'll hack the junk (very badly rusted) pump to test.
The exhaust manifold is a plain old log, but actually a pretty free-flowing design, with three simple flat two-hole flanges so making headers would be simple. Exh ports are paired 1-2, 3-4, 5-6. Firing order is 1 5 3 6 2 4.
Uses a Ford style starter. The manual trans version of this motor is an exact bolt-up to the later AMC six, 64-71, bellhousings, clutches, trannies. (Post-72 AMC consolidated 6 and 8 patterns). The one oddity is that the automatic cars have a different crank butt! There's a lump on the end that needs to get removed on a lathe, then a manual flywheel would fit. I have a NORS shortblock here that is an auto crank so I'll be doing the lop-off and could let you know how that goes :-)
Oh yeah -- this engine is SMALL! It's heavy, but short! Like 9" shorter than a 232. Really. And narrow. That's why the 232 or V8 won't fit in the early Americans without substantial metal hacking.
The front of the motor is ordinary. I've heard reports of harmonic balancers rotting out, but NEW ones are available now. $120 or so.
The ignition is a Delco Remy. I'm playing with it now. I have a 195.6 ohv in my 63 American, that I commute to work in, 90 miles a day on the 405 in Los Angeles (yeah, that's as weird as it sounds). (3 speed with OD) After driving it 6 months I realized... I've never heard it ping!
It's set up with 21 degrees TOTAL spark advance, at speed! Unbelievable. Damn right it won't ping! I'm currently running it at 36 degrees total advance, it's quite happy. I got it to ping, once, climbing a hill, shifting into 3rd.
