[AMC-list] it runs...

[tom jennings <tomj@xxxxxxx>]

I got my new 195.6 OHV running, but not without problems.

I replaced the oil pressure relief spring with a shorter/softer one,
refilled etc, and within 5 seconds puked oil out the same place (pushed out
the oil filter gasket). Then I tried the "other" plunger. Same thing. Then I
put in the shortest, softest spring, and ... it held.

Thing is, it ruined my new oil pressure gauge within the first 5 SECONDS! So
I don't know what the operating pressure is, now; 0 psi shows as 30 or so,
but I eyeballed it by assuming that if it's not pegged (and stays intact)
I'm OK... there is certainly enough oil pressure for the cast iron to be
happy.

Since I hadn't tuned it or adjusted the valves it didn't idle so I kept it
varying around 1500 rpm, got it warmed up, the oil pressure dropped
accordingly. I set the valves with the engine hot and not running (close
enough for now) I had 'em all too tight, twisted the distrib and idle
mixture and it idles roughly at 700 rpm with 18 inHg vacuum, so "good
enough" for now. (The carb is new out of the box.) Ran it for probably 30 -
40 minutes. Next time I'll retorque the head then tune up to spec.


I'm a little worried about the oiling still. My working assumption for the
design was, the oil pump cannot deliver more oil than the relief valve can
bleed off. I'm wondering if there are more restrictions "upstream" of the
main gallery (hose, filter) that allows substantially more than the relief
pressure to build. I was assuming the "head" would be 2 - 5 psi, but that
even 20 - 30 psi would be OK. There are two 90 fittings in the system, but
the rest are 180 degrees, and the hose is 1/2", where the block oil ports
are 1/4" to 5/16". I know that 90's can be very restrictive. I could easily
replace them with 180's.


The 100psi gauge PINNED and bent in seconds; that's not just "a few psi"
high! It bugs me that I have four 195.6 OHV relief springs and all four are
different. The (wrong) plunger and tall spring I got from Galvin's. The
softest one did work however, and it was the one that came out of this
engine. Luckily it was just a $20 Sunpro gauge from Pep Boys.

Two of the springs are 23 turns, two are 21 turns. All exactly the same
design and diameter within .001", but all different lengths. Three of them
are used, one new. I did not measure the exact length of the spring
installed, but it's trivial to pull and measure, and I will be doing that. I
think I will also cobble up a bench spring compressor scale so I can
actually measure these things.


So Friday I will buy YET ANOTHER Pep Boys gauge, and now that it idles, I
can check rpm vs. pressure and check that with the current spring that it's
not going over spec. So it could be one of the following:

* Simply the wrong spring and plunger, hence problem solved now.

* Extraordinarily high upstream pressure even with a reasonable relief
pressure.


But it seems unlikely I did any damage the first time, since the "big leak"
from the popped filter gasket simply relieves pressure, it doesn't drop it
to zero. Whew! What a f*** relief!!

Messy driveway though.


I had a lot of other typical tiny under-hood problems (wrong wire to fan,
fan polarity backwards, etc) nothing serious, just typical trivia.


Man, this 195.6 OHV is a mess of little mysteries. Hopefully I'll get to
sort it out without blowing it up.
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