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Oil pressure light at higher speeds - Eagle

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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/08/2018 at 11:27am
Perfect fit for the 6's. Which this is, and likely stock.
(And last ones i bought for a 390 were also correct diameter....)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jun/09/2018 at 9:00am
IMHO the last couple series of AMC sixes 64-06 199/232/258 & 4.0L) are some of the finest engineered mass market engines of the era, so discounting the exotic low volume (and expensive) stuff and things like pure race engines. The issue with oiling on the early shaft rocker sixes is that the passage in the block to the head is small and can be clogged with lots of low speed driving and pushing oil changes. Solution is easy -- slightly reduce the diameter of the head bolt feeding the rocker shaft (http://www.mattsoldcars.com/RestoreAmerican/boltmod.shtml). Of course with today's oil I doubt this is necessary -- especially not if you change it regularly and do more than just putt around town. It wasn't necessary for most people when the engines were new -- the problem didn't crop up until a couple years after the engine was introduced (TSB to fix was issued in 1967). AMC fixed the issue after 1970. If I were rebuilding a 64-70 engine and found the head bolt was unaltered, I wouldn't "fix" it. Today's oils are that much better than 1960s oil.

Another thing I've found is that the piston to bore clearance is tight on the six. Only like 0.002"-0.004". Increase it much beyond 0.004" and you get a piston "tick" on the 258 and 4.0L (might not on the shorter stroke engines). Chrysler had an issue with this shortly after taking over AMC. AMC had been rejecting or overboring blocks that had 0.003" or more clearance. Chrysler engineers didn't see an issue with that, and ordered the engine plant to pass many through. So after 20K or so miles the many late 80s 4.0L Jeeps developed a slight (but noticeable) "tick", similar to a loose lifter, but definitely in the lower part of the block. They would run on for many miles like that, but many owners traded in low mileage Jeeps that the dealers had a hard time unloading. A local dealer (when I was in Georgia) sent a couple motors to a local machine shop, where they discovered 0.004"-0.006" clearance in all, and that the pistons had a very slight rock at the bottom of the bore causing it. Tighten up the bore and it wasn't there. That's not much wear, I know. I ran a 4.6L stroker that was bored when rebuilt to 0.006" clearance. It always had a tick, but I put over 70K on it before it started using oil -- always had good power. When rebuilding I discovered .016-0.017" clearance at the bottom of the bore, 0.010-0.012" at the top. The rocking was enough to accelerate wear, but as I stated, the engine always had great power, never noticed any power loss. Oil consumption started going up noticeably the last 10K miles or so though, which prompted pulling the head (though it was bad valve stem seals) for inspection. My brother told me he didn't think it could suck that much oil past valve stem seals unless the valve guides were also REALLY bad... he was right!
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jun/26/2018 at 11:13pm
test don't guess.

i use electric senders, but they are far less reliable than they ought to be (i dont know why, but they fail far more often than temp and other senders). i keep a cheap Summit brand "mechanical" in my shop. it's only 5 minutes to pull a plug from the block and install and check.

as much as i dislike the skinny line, waiting to be whacked or vibrate and leak, i'm going to install one under the hood. and use both an oil pressure switch AND oil pressure sender in my home made electrics.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vinny Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2018 at 10:08am
I got a 74 Dart 318 convertible going in Vancouver a whole bunch of years ago that had been sitting outside without a carburetor. A junkyard carb, new lifter and oil change later, I took it for its first ride up the hill to SFU. The light flickered all the way. After sitting for a few hours it started and no more problems with the light. I am pretty sure that the cause was just a lot of condensation in the sending unit.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2018 at 9:51pm
lol, on my trip out to the hot rod power tour, some 6500 miles, my oil pressure sender died, scaring the crap out of me. about 1000 miles later i thought to at least install a Jeep type three-legged oil pressure SWITCH, the one with the fuel pump contacts. i wired it so that when there's oil pressure it GROUNDS the old oil pressure sensor line. this makes my little computer happy, no-oil-pressure-equals high resistance (NOW SWITCH OPEN) and any-oil-pressure-over-5-psi-equals low resistance (NOW SWITCH CLOSED). success! in short(er), the switch simulates a "sensor" where no oil pressure is 0 PSI (open) and any oil pressure is 110 PSI (closed).

the point of all that text?

two weeks later, 2500 miles or so, the !#@$%$@ Echlin switch from NAPA failed. false reads of OPEN (no oil pressure) when my crap mechanical gauge under the hood shows normal.

WTF is with oil pressure sensors and switches?!

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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