|
| 1963 Rambler 195.6 OHV with E-Stick clutch (there's a reason why you've never seen one of those...)" |
The Nash-designed six used in the Rambler Americans (and other Rambler models) is the end of a long evolutionary line. It's very old-fashioned, and more or less a dead end, viewed from the present. That's not a complaint at all; it's a fine old motor, very reliable, and since Nash ran it for 40+ years, it can't be too bad. Variations of this engine were valve-in-block and overhead valves. The final incarnation was also it's largest displacement, 195.6 cubic inches. Looking at the block, it's easy enough to picture the wooden mockup used to make the molds!
(Continued below ...)
The cylinder head is a major focus on any engine but this one in particular because of the peculiar intake design and the chronic head sealing problem.
It's heavy, very under-square (long stroke, small bore), breathes poorly (not that it matters at the low speeds this thing turns), has barely partial-flow oil filtration, and has poor cylinder head sealing. There are absolutely no, zero, aftermarket performance parts made for the overhead valve version; there were a few aluminum heads available for the flathead. That's it.
But it's stupidly reliable, grossly over-built, (forged crank and rods, fat castings), a fine cooling system, flat torque from just above idle to 3000 rpm, is very easy to maintain, and parts are readily available. It's easy to retorque the head and adjust the valves as per the recommended schedule; 40 minutes total. It's also very, very small; it fits into the 20" wide engine bay of the little American/Nash Rambler. It runs as smooth as a Swiss watch. I commute on Los Angeles freeways in one, so there you go.
The motor in my 1963 Hardtop American is "recently" rebuilt; though there is no way to know, I would guess around 1980. I rebuilt the head, but there was zero cylinder wear, compression is fine, and after 6000 miles (Oct 2008), the then-new plugs look perfect, no oil ash. It leaks all over the bottom end, but otherwise seems quite healthy.
I hear a lot of complaints about this motor, its tendency towards head cracks and cooling problems, but "everyone" is wrong -- the three motors I've had personal experience with, all were rebuilt multiple times, and show quality work done in the past, then driven well past end-of-life, with some catastrophic failure that finally did it in, usually a leaking headgasket, probably when the car was finally sold to some kid as a "junker" or first car and maintenance stopped. You don't bore "junk" motors out twice, and all of the final-catastrophic problems I've seen were completely preventable -- and always related to head-sealing, almost certainly ignoring the retorque requirement. And it's not fair to call engines that were used for 30, 40 years then failed, "bad engines".
I'm building a new motor, a 195.6 OHV, currently at a snail's pace. The engine in my hardtop seems quite fine, but it leaks oil from every gasket, and who knows what it's long-term prognosis is.
So far I'm a bit unclear on what my final goal is, but these unvarying criteria:
It appears that by design the crank weights dip into the oil sump, and though my motor has tight rings and burns no oil, and has good working PCV, there's a mist all over everything. Mist comes out the huge, tall filler neck. That needs a re-think. Maybe a simple crank scraper tacked into the pan. I'm not sure how much I can do here.
I had the 232 now in my Classic wagon "bench balanced" (juggling pistons and filing rods) and it's been super smooth and silent for 20 years now, and with this much rotating mass and long stroke, it seems like a good idea.
I am planning on installing a small turbo charger, with a horsepower target of 150 - 160hp, which means 4 - 8 psi boost, which is easily done. The RPM range will not be extended, but I'll talk to the machinist (when I find a decent one) about balance for sustained "factory stock" speeds -- 4500 rpm. (Believe me, in this motor/car combo, that is high speed. This is an old motor!)
I have been assuming I'd do TBI injection, but I've had a harder time finding a throttle body donor than I have had finding turbos. And at these CFM and power levels a side-draft Carter YF (Corvair's used 'em) would be just fine. So this is TBD.
I've been packratting parts, as these motors were not popular and they're all ancient. Cylinder heads especially since they often crack. There seems to be a lot of tiny variations to the same casting for inexplicable reasons, luckily all are interchangable.
This is a "trough" type intake, cast-in-head like many early sixes (Chevy, Willys). Cheap to make, performance poor, and it makes the engine ver narrow (good, here). A cast flat aluminum plate over the trough means making turbo and EFI adapters easy.
Just got two cores back from the local machine shop for cleaning and inspection. One came from U-Pull-It, off a 63 Classic that had a ventilated block, and a clearly, recently rebuild head. Nice find! The other was a junk motor pulled from who-knows-what and picked up for free by me out of someones storage unit cleanup. This one had water in the oil.
The Classic head that looked so perfect turned out to have a very well done repair to a head crack in #6 cylinder exhaust valve seat. Burned #6 sounds to me like a plugged up water jacket with no coolant flow in the back of the motor (slight tilt rearward). When I got it the head was nicely painted, different from the motor, so I assume it came from commercial engine rebuilder. See photos.
The other head cleaned up nicely, with not much wear, and zero crack damage. This will become my turbo head. The only substantial difference with this block the lack of tapped plugs into the water jacket between the exhaust ports.
The only head work I plan on doing is to polish the exhaust ports and valve bowls as much as I can to minimize heat pickup, as it seems to me to be a major design limitation: exhaust passages are long with two 90's, and anecdotally, this motor warms up -- produces usable cabin heat -- within 2 - 3 minutes of driving. That is is coming off the head!