Inliners International Forums General Discussion Engines Rambler 195.6 OHV performance/rebuild

I know most of you have GM iron, but I hope you won't mind me posting about my most recent project, a Rambler 195.6 OHV inline six. This isn't the "new" AMC six, it's the old Nash-based one, AMC stuck overhead valves on an ancient Nash flathead in 1958.

Let's just say it's not a popular motor. But it's a forged bottom end brick s**t-house, with a lot of low-hanging fruit, they're fairly common even still, and it's the only engine that fits in the tiny bay of the early Rambler American chassis. (This engine will bolt right into any Nash back to the 1930's I think.)

There's not a single aftermarket performance part for this engine, not even a chrome air cleaner, so I made or did everything myself.


The page is at http://wps.com/AMC/195.6OHV/index.html

Tom, that is a thing of beauty. Full marks to you for taking on a difficult task and showing the set in our ways,rest of us that there are other ways to produce a top line finished product.

regards,Rod

Again your report is an education for many of us, and a fine piece of engineering, in every sense. i especially value your emphasis on reliability as well as performance.

Thank you for high quality work on an neglected engine.

God's Peace to you.

d
Inliner #1450

Tom:

What a great resource! thanks for putting the information out for the rest of us. Lots of really good stuff there and great ideas on how to handle issues of this type on other obscure engines. Can't wait to see the rest of the story on the ignition.

Sincerely:
Paul...aka xerxes

FANTASTIC documentary on this unusual engine!
Great pictures and some worthwhile mods (enjoyed the fan coding too...)
I was keying things in to Gonkulate how much power it might make, but couldn't find the cam specs - (lift, .050 events, etc)
Did they get missed or did I miss them?

"A new camshaft (OK, reground) and new bearings were installed. This was an "RV" type grind bought from Doug Galvin. Cam specs are below"

Wow, thanks for all the kind words! I've never been so freaked out on an engine build before, no one seemed to know much about it beyond the most basic, and I'd heard all sorts of bad stories about this engine. I wouldn't hesitate to build another one at this point, I think I know what crazy crap to look for.

The only remaining "mystery" is the oil pressure relief valve spring nonsense.

The cam specs I will enter tonight (just re-found the sheet) but here they are:

at 050 lift:
duration 202 degrees, I and E
108 degree centerline
108 degree separation
.39" VALVE lift

Comical for a "performance" cam, eh?

The ignition ought to be "interesting". I got the Megajolt Jr kit built today (wrong part, on it's way). Ugh, I hate working with surface mount parts. I have to weld up a mount for the coil pack, do wiring, etc.

The Corvair nuts have worked this out already. I'm a major fan of those guys because they too have to make a lot of their own stuff, and there's enough of them doing so to have decent projects. Basically the guy who first did it points out how incredibly easy it is to bring up -- you run the engine on your old stock system, but put the timing light onto the EDIS system that runs simultaneously! When you see it all working OK you switch over the plug wires! Nice!



This motor has a very old fashioned spark "table" (or however you want to talk about spark timing). Stock, it's 11 degrees mechanical advance, max, and 5 degrees static -- 16 total advance! (Another 11 for the vacuum advance).

I'm going to measure mechanical advance, on the car, at 1000, 1500, 2000, etc rpm (rows), then do the same with vacuum advance, 0, 5, 10, 15, 20 inches of vacuum (columns), make a spreadsheet of the sums, and enter that as my initial table in MegaJolt.


I hacked the distributor for 20 degrees mechanical advance, and I run about 13 static, for 33 degrees total. It has never pinged. It's old and worn, so there's timing jitter. THat will go away with EDIS.

I'm aiming for "DONE!" by October, there's a vintage rally run, some 600 miles in two days of mountain and canyon roads. I want to beat some import sports cars in my Rambler :-)

Tom, can you describe the car?
Rambler American I gather, but details, trans, rear gear, etc?
Looks like about 2600 lb curb by what info I have but that is a guess?

Did you do anything to raise compression or still the stock 8.7cr?

It's the one year, one model hardtop, the '63 American. 3.78:1 open axle, T-96 3-speed trans (1st not synchro) with R10 overdrive. The hardtop "440 model" with bucket seats and console shifter, with the "Twin Stick", two shift levers. Really nice complicated electrical logic with pushbutton OD kickdown. I think it's 2500, 2600 lbs but I got to get to a truck scale to be sure.

Compression ratio is still 8.7:1. It's happy with the crappiest gas. I only got it to ping once, when I was experimenting with ignition timing.

Hot-rodded Gremlin drum brakes up front (9 x 2.5). http://wps.com/AMC/1963-Rambler-American/Drums/ just about as good as drums.

It's also the last Nash designed car on the road, ever. 63 was it, 64 was a total AMC redesign.

Page for the car is at http://wps.com/AMC/1963-Rambler-American/index.html

Tom,
Thanks for the detail. I was curious how much (on my computer the Gonkulator) the mods you describe might make. I was pretty conservative in describing the changes in the computer but here is what I got.

I compute the gross torq/power of the 196/138hp as
Torq 175 at 2800
Powr 130 at 4500
In your car, the stock engine should run as:
2.51 60ft time
11.53 at 58.7 1/8 mile
18.23 at 73.1 1/4 mile
12.0 0-60mph

With the mods you've done to the engine and exhaust-no other changes:
Torq 182 at 2900
Powr 148 at 4800
I do NOT know if the bottom end of this engine is strong enough and has a good enough damper to shift at 5200rpm, but "shifting" the computer there it calculates to run:
2.48
11.05 at 62.0
17.40 at 77.2
10.36 0-60mph
That's almost a full second quicker in the 1/4 and almost 2 seconds quicker 0-60mph. Not bad!!

The cam you chose seems to me plenty big to be in the rpm range you want to be in. It is starving for air with that little 2v-Weber carb on it, but I know the intake manifold trough looks like it limits what can be done. Just for fun, I calculated what might happen if you grafted three of those 2v-Weber carbs onto the intake trough:
Torq 184 at 3300
Powr 156 at 5000
2.47
10.97 at 62.6
17.25 at 78.1
0-60mph 10.1
Seems it would be fun, but you may be near the law of diminishing returns already. I dug around for a few more AMC details along the way (6 and the old 250-287-327 v8 too) so learned a lot. Thanks again for posting on this rare engine.

Wow, thanks Duece! What software do you use for that? I have "SC Dyno Sim", it's been... OK, but RPM range starts at 1500, and it's a bit old at this point. The numbers it produces seem off (107 hp for my engine, stock) but I was using for 'what if's on cam, carb, valve size, etc and didn't really care about 'numbers'.

I measured 0 - 60 mph with a stopwatch as 15.9 sec +/- half a sec, three passes. But that was with a very tired engine (compression was even but 110 lbs, about) and ran out of torque around 3500, and no way I was confident enough to spin the old thing above 4000.

I'll repeat (same road, same stopwatch) with a motor with good compression (145 - 150), cam, carb, etc. It pulls like crazy to at least 4000 now.


Forged crank and forged rods, but only four main bearings. HUGE journals, like a truck; wide and big diameter. (This makes the engine VERY short.) Vibration damper is new manufacture (repro). I don't know what would determine max. usable RPM other than shedding parts, and my research budget isn't big enough to find out :-)

Truly, thanks for running those numbers. They do jive with experience; 130 is probably correct, stock, and a gain of 18 sounds optimistic, but it's hard to appreciate just how hobbled these engines are from the factory!

Tom,
It's my own home grown "Gonkulator" computer. Been working on it off and on since the 1970s.
Well ok if I make your car 100 lb heavier, shift really slow at 3600rpm, and with a very gentle launch, and knock off 4% power across the board for the tired compression readings you got (probably a fair guess) I now get
Torq 168 at 2800
Powr 125 at 4500
2.91 60ft
13.18 at 53.7 1/8 mi
20.39 at 67.5 1/4 mi
15.7 0-60mph
Hey, it will still nose out a 1-bbl Rambler Classic (tested Feb 63 Motor Trend).

If I compute your new build the same way (same slow launch and gentle shifts, but at 4500rpm), I compute
2.77
12.06 at 57.9
18.71 at 74.7
12.1 0-60mph
Still a lot faster, see what the stopwatch has to say.