Re: [Amc-list] 401 Oil Mods (AMC I-6 oil issues)

[Frank Swygert <farna@xxxxxxx>]

Oh there are some Jeep mud racers and even some road racers that have revved them up to 6500 rpm or so! 6000 is about the point where a harmonic vibration sets in, but if you go PAST that point it's fine -- just don't run AT it. From what I've been told there is about a 100 rpm window. 50 rpm before the vibration starts and 50 beyond it's fine to run in. The exact point varies slightly with the specifics of a particular engine. Most of the Jeepers/road racers run 258s, and their "bad spot" is supposedly right around 6000 rpm. My 4.6L runs completely out of steam by 5500 (gets that far and all but dies, mainly due to my cam, but the Renix computer might have a rev limiter at 5500). I hardly ever run past 3000 rpm though, no need to! 

199 used flat top pistons. Your 232 has got to have 9.5:1 compression or better with the flat-tops. Maybe closer to 10:1, I'm not sure. That might be a problem when you convert back to gasoline. May have to run premium at that compression, might get by with mid grade though. That's the only problem I can see.

Oil capacity IS a problem with the six. I always run mine 1/2 quart above the full mark on the stick to avoid that issue. I don't think the crank will touch the oil with the extra 1/2 quart, and even if it does when the car is at rest it won't matter -- that 1/2 quart will be circulating through the engine in just a second or so, way before any oil is churned up. Jeeps don't have this problem with the deeper sump. Never had it with my Cherokee, Commanche, or J-10. Those I just run at the mark, the cars I run 1/2 quart over. I doubt a full quart over would hurt a thing. The police oil pan for the V-8s is outwardly identical to the standard V-8 pan (police has a different baffle inside), but they were spec'd to hold an additional quart of oil. I was told the only reason the V-8 specs said five quarts was for economics -- owners wouldn't like changing six quarts of oil every time when the other brands only needed five. Besides, five quarts is more than adequate for 95% of driver
 s. The others learn to add another quart. 

----------------
Date: Mon, 17 Mar 2008 08:52:51 -0700 (PDT)
From: Tom Jennings <tomj@xxxxxxx>


On Mon, 17 Mar 2008, Frank Swygert wrote:
> As for the sixes, well, they've never had oiling issues that
> I know of! The only exception is the early 199/232/258 with
> rocker shafts. Those need a mod to one of the rocker shaft
> bolts to allow more oil to the shaft.


Also, no one revs much past 6000, even Navarro didn't get much
faster than that. I doubt most people rev a 199/232/258/4.0
past 5000.

Hopefully next month (soon as the trans is back in the American)
the Classic's 232 gets torn down. Since it was 100% propane
and synth oil for 20 years, the wear patterns in there will be
pretty much 100% mechanical wear patterns. I did change the
cam and lifters back in 92 or 93 otherwise it's been sealed
the whole time. I built it myself very carefully using a great
machine shop in San Francisco.

It's the old-style rocker shaft WITHOUT the mods.

Besides that issue, are there other issues with this motor? I
know it doesn't rev high, but how much oil stays in the air? This
motor's tended to run the oil pickup dry on hard turns (idiot
light comes on) obviously hasn't killed it... I assumed I put
the pickup in slightly off, but is there a sump issue?

GIven a stock 70 head etc, are there combustion chamber issues
to watch for? I don't think I've been able to run as much ign
advance as I should without pinging, so I may have squish area
AFU (it's got 199 or is it 290 flat-top pistons in it).

-- 
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)


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