New engine

Well the decision is made. I am replacing my engine (O360) with a
Lycoming factory reman. I have a few questions for the group. What is
the feeling about the new roller cam? They offer roller or regular for
the same $$. Any comments pro or con? The engine comes stock with
Slick mags with the option (more $$$) for Bendix mags. Is there a
preference? I have heard/read that the Slicks are difficult/expensive
to overhaul. Are there any ADs on the Slicks? Right now I have Bendix
mags installed.

Regards,
Jerry

Well the decision is made. I am replacing my engine (O360) with a
Lycoming factory reman. I have a few questions for the group. What is
the feeling about the new roller cam? They offer roller or regular for
the same $$.

Wow -- that's surprising. First, I'm amazed that they are still
selling the old non-roller engines at all. Second, I'm amazed that
it's the same price as the new technology.

If I were you, I'd snatch up the roller cams. I know I sure wish I had
'em in my O-540.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Roller,,,, Hands down.....

Ben
www.haaspowerair.com
wrote:
Well the decision is made. I am replacing my engine (O360) with a
Lycoming factory reman. I have a few questions for the group. What is
the feeling about the new roller cam? They offer roller or regular for
the same $$. Any comments pro or con? The engine comes stock with
Slick mags with the option (more $$$) for Bendix mags. Is there a
preference? I have heard/read that the Slicks are difficult/expensive
to overhaul. Are there any ADs on the Slicks? Right now I have Bendix
mags installed.

Regards,
Jerry

On 31 Oct 2006 14:01:04 -0800, wrote:

Well the decision is made. I am replacing my engine (O360) with a
Lycoming factory reman. I have a few questions for the group. What is
the feeling about the new roller cam? They offer roller or regular for
the same $$. Any comments pro or con? The engine comes stock with
Slick mags with the option (more $$$) for Bendix mags. Is there a
preference? I have heard/read that the Slicks are difficult/expensive
to overhaul. Are there any ADs on the Slicks? Right now I have Bendix
mags installed.

Regards,
Jerry

Roller cam for sure and if it was me I'd keep my old mags and get them
rebuilt.

wrote:
Well the decision is made. I am replacing my engine (O360) with a
Lycoming factory reman. I have a few questions for the group. What is
the feeling about the new roller cam? They offer roller or regular for
the same $$. Any comments pro or con? The engine comes stock with
Slick mags with the option (more $$$) for Bendix mags. Is there a
preference? I have heard/read that the Slicks are difficult/expensive
to overhaul. Are there any ADs on the Slicks? Right now I have Bendix
mags installed.

Regards,
Jerry

I look after six airplanes, all having Lycoming factory remans.
(4 O-320s, 1 O-235, 1 O-540). Three of those O-320s we replaced just
this spring. The Lyc prices were lower than having the old ones redone
closer to home, and we were able to keep the turnaround time to much
less.
One of them has the roller cam. I notice no difference in noise
or performance. I think the cam will last longer; I just hope Lyc has
tested the setup well enough. The roller will have less contact area
than the old lifter face, placing more pressure on the cam lobe, though
not rubbing it so much. The camshaft itself is ground differently to
accommodate the roller, with a more square profile to get the same
travel characteristics as the old lifter, and maybe the camshaft metal
is tougher. One of Lycoming's weak areas was the camshaft, with more
wear than Continental. We use only Aeroshell 15W50 because it has the
additive recommended by Lycoming to protect that shaft. The crankcase
is modified to fit the new lifters, which have an indexing feature to
keep the rollers lined up with the cam. You can spot the roller-cam
engines by the much larger green pushrod tube seals at the case.
Five of out six engines have Slick mags, which all work well.
They are no problem at all to service. We stick to the 500-hour
ionspection intervals, removing the mags and opening them up to check
the points and distributor. Those parts usually need replacing around
the 1500-hour mark. There are very few ADs on modern Slicks. The O-540
has the dual Bendix mag which is a certified first-class pain to
maintain by comparison.
Only beef: One of the carbs on the recent engines ran rich
enough at full throttle to be rough in the climb. Turned out that the
accelerator pump check ball spring was missing and extra fuel was being
drawn past the valve.

Dan

In theory the roller cam seems the way to go. I just hope Lycoming is
having better luck with cams than they did with crankshafts.

I don't know where you heard that about Slick mags. They are far
easier to work on than TCM Bendix and Slick has actually improved them
over the years. Slicks have very few ADs against them and the newer
models none at all. I do think that when you add up the price for all
the individual parts that would be replaced at overhaul (i.e. more than
just points and capacitor) you are typically within spitting distance
of the price for a new one.

John Dupre'

wrote:
Well the decision is made. I am replacing my engine (O360) with a
Lycoming factory reman. I have a few questions for the group. What is
the feeling about the new roller cam? They offer roller or regular for
the same $$. Any comments pro or con? The engine comes stock with
Slick mags with the option (more $$$) for Bendix mags. Is there a
preference? I have heard/read that the Slicks are difficult/expensive
to overhaul. Are there any ADs on the Slicks? Right now I have Bendix
mags installed.

Regards,
Jerry

Theoretically the spalling/compressive hertzian (sp?) stress on a cam
will be greater running against a radiussed roller compared to when it
is running against a flat lifter - providing the lubrication is there.
I'm convinced that what fails Lycoming cams is mediocre or non-existant
lubrication during cold starts. The solution is simple - religiously
preheat the oil after any extended shutdowns or under cool conditions.

In Lycomings, the camshaft is above the crank. If the crank doesn't
turn fast enough, cold con-rod oil blobs won't initially be thrown high
enough to lube the cam. In addition, the crankcase is such that the
cam lobes are not in line with any big-end rod journals ends which
might otherwise sling oil towards the cam faces.

Instead, the cam must rely on residual startup lubrication being
replaced with a general fog of oil that will eventually develop in the
crankcase - but that won't be happen until the oil thins out from heat.
In the mean time, the cam is unlubricated. If the cam or lifter
surfaces ever begin to spall, case hardened metal is released inside
the engine and the failure can be expected to cascade.

Two of the cams lobes operate a total of four lifters on opposite sides
of the engine. The first lifter to fail will be one of the two which
are the last to get startup lubrication, given the direction of
rotation of the cam.

To add to this start dilemma, when the oil is thick or cold, very
little oil goes to the active or hot parts of the engine such as the
cylinders. Instead it must blow over a relief valve and oozes back to
the crankcase. The oil blowing over the relief valve has no access to
the combustion heat of the engine. Hence it is very hard to warm the
oil by simply starting a cold engine or preheating only the cylinders.

Roller lifters may help the cold start canmshaft situation but it is
not going to help the cylinders etc. Others talk of oil getting to
bearings etc but it is the expensive parts of an engine that must rely
on incidental fog type lubrication.

Comments?
nrp

nrp wrote:


Roller lifters may help the cold start canmshaft situation but it is
not going to help the cylinders etc. Others talk of oil getting to
bearings etc but it is the expensive parts of an engine that must rely
on incidental fog type lubrication.

Comments?
nrp

It's a dilemma. The cold oil won't fling or fog well, and if we
raise the RPM with really cold oil we risk cavitating the pump and
getting little or no oil at all. We use Aeroshell 15W50 to try to get
the lower viscosity in cold weather without losing the lubricity when
hot. Seems to work OK, but the airplanes are also in a heated hangar
every night and the cowls are blanketed between flights when outside.
I think an airplane parked outside year-round (or in an unheated
hangar) should have, besides an insulated cowl cover, both a crankcase
heater and a fan heater under the cowl, and another fan heater inside
the cabin. The case heater will thin the oil, the cowl heater will warm
the jugs, battery and mags (impulse couplings sometimes stick when
cold), and the cabin heater will warm the gyros so the bearings don't
go out so soon. Of course, some folks don't have access to electricity,
or have to show up two hours earlier to plug things in.
As I get older I begin to understand why so many seniors leave
Canada to go to Florida or Arizona for the winter. The cold just makes
life so much more difficult.

Dan