Close call with engine failure in IMC

I'm close to finishing my IFR. I did most of my training at night
but didn't get much IMC. Two out of the past 3 flights were in solid
IMC. Fortunately the night training was pretty good and I've
become somewhat comfortable quickly after the past 4 hours of IMC or so.

The plan was to do my required long XC.

KSQL RV STINS V199 ENI KUKI followed by
UKI ENI V494 SAC KSAC
KSAC SAC ALTAM SUNOL HWD and then VFR to SQL.

Well before the last flight, the weather was mostly
clear with a few clouds. Predicted were +1 degrees
at 6000 with MEA's at the 5000-6000 and rain. My
CFII knows the area damn well and can fly it blindfolded
with lots of IMC experience and thousands of hours in Archers.

We took off, all is good. Get to STINS about 5 miles off the
coast and my instructor commented that that visibility is
quickly getting MVFR. I'm happy as I want IMC experience.
I take off the hood and fly. All is good. I have the plane
trimmed for hands off flying and ready to get bored with 50
minutes more of cruise. Over the next few minutes I notice that
I keep having to put more and more nose up trim...just
a blip of the electric trim. I also notice I've lost 100 RPM
but I figure maybe it was just I didn't set the power correctly
a 4-5 minutes earlier or by leaning and trimming/pitch (less likely
of course). Well this continues and my CFII puts on the carb
heat and full power for 45 seconds. Power is resumed. We comment
that it is strange since carb ice usually happens at 50-60 OAT
rather than +3 celsius. After a couple of minutes RPM
decreases again. We again apply carb heat and we instantly
gain power. We check and we're now closer to our
destination and definitely STS than from home or an unintended
stop at SFO. We repeat this process for a while. knowing
the ceiling is around 4000 just 1000 feet below us. This
whole time we are also keeping a close eye on the engine
oil temp and pressure. All is in the green and holding steady.
We do the approach into UKI breaking out of solid IMC at
around 3000 and go missed. the engine seems ok in the
climb out but again start dealing with ice again. We
head to SAC and about 20 miles out we break into VMC where
the engine clears and we don't use carb ice again for the rest
of the trip. We do the approach SAC then HWD and then continue back
to SQL.

Today my CFII calls me and tells me they found the plane with a
streak of oil on the cowling and one person said that he thinks
it is a cracked cyclinder but the full analysis hasn't been began
yet.

Right now I'm ready to go to Vegas as we got quite lucky
we didn't have an engine failure at 5000 feet and 7nm out to
sea. I dont' like swimming to say the least.

IFR scared me to begin with...."PPL is a license to learn. IFR
is a ticket to kill." I'm not afraid of the flying but the
additional risks and workload that go with it. I'm now setting
new minimums for me.

Mountains without IMC and not at night

IMC at night with another pilot unless the route is really really benign
and I'm very familiar with it.

LFIR - only if very local.

IMC only in planes I've flown recently and know well.

I'm sure I'll come up with others.

Gerald Sylvester