Geez, go away for a little bit, and you guys really filled my
mailbox. Oh well, time for another digest of assorted ramblings.
>Rich Hill asked several questions about cam timing, then had a
>45H (MGB) needle put in his carb:
Checking cam timing without the right tools is really hard, and not
very acurate. However, if you still have the cam card (all the specs)
we can attempt to put together a testing method with minimal tools.
Needed info would be timing and lobe centers for both intake and exhaust.
Other info would be helpful. If you want to try this, might want to
move it into email. "taylor!randy@chrysanthemum.cs.odu.edu" seems to be
my most reliable address, at the moment. "randy@talor.uucp" should work,
but doesn't always.
The MGB needle is leaner at some points, and richer at others. Odds are
very remote that it's right all the way through the curve.
>On a related note, Chris Kent Kantarjiev writes that the needle would be
>richer because it was designed for a 1800 cc engine vs. 1500:
Displacement has no direct bearing on carburator jetting. Things that do
influence jetting are:
Intake tract efficiency. This includes valve timing and lift, valve
size, port shape, intake shape, combustion chamber shape, even the
air filter shape. Anything that effects how the air flows into the
engine.
Exhaust tract efficiency. Same as above, except applied to the exhaust.
This includes how restrictive the muffler is.
Bore-stroke ratio. Actually, this is minimal effect, and can be called
a change in combustion chamber shape.
Stroke-rod ratio. This has a major effect on the rate of combustion
chamber volume change rate relative to valve position.
Now, obviously any change in displacement is going to have an effect on
several of these things. But, nothing in there says whether the effect
is going to cause a richer or leaner condition. In the example here,
the MGB needle is leaner at the lower range, most likely due to the
incrediably bad air filter design, and richer at the top side, due to
the equally bad intake/exhaust manifold.
>On Spridget bulbs
I use 1157 in the dual sockets, 1156 for single socket "bright" applications
(brake lights, turn signals), and either 1071 or 67 for single marker lights.
A 1157 is just a 1156 (high power) and a 1071 (low power) in a single package.
>On Grose jets
I always install gross jets in the nearest trashcan. They are not the right
length, and cause the float arm to operate at a non-optimal angle. They will
hang (either open, closed, or in between) sometime. My Mini has a scorched
wiring harness right above the carbs from the one time I tried them. Exhuast
system is right below the carbs.
> Pinging and timing (mainly Phil)
Overly advanced ignition timing is only one of the causes of pinging, and
may also lead to a slight temp rise. If the timing is close to where the
factory calls for, look elsewhere. With the Europa, if the temp is up and
it pings, I'd look at the cooling system. Make *sure* it's properly bled,
especially if it's one of the ones with excessive French heritage. (I can
make fun of them, I had a S2 for six years).
Here's a head-scratcher for you. A 72 Ford Pinto set exactly to factory specs.
With 70% antifreeze in the cooling system, it pings like crazy. Drain it
and fill it with 50% (or less), and it stops pinging. In both cases, the temp
guage read exactly 180 degrees. First person with the correct answer about the
cause of this gets a FREE!! years subscription to british-cars-digest. :>
>Robert Jones talks about his MGB brake system.
The rear brake adjusters have four flats on them. Any time you turn the
thing, make sure you stop centered on a flat. You should be able to feel
this point with a wrench. Now, randy's technic for adjusting new brakes on
a car of unknown history. First step is to back the parking brake cable
adjuster off until there is plenty of slack in the cable. Make sure that
the cable is free, and both rear acutating levers are fully retracted.
Now, adjust both rear brakes until they just lock on a flat. They're going
to lock each time you turn it "over the hump". Get in the car and stomp!
on the pedal a couple of times. Maybe even smack the outer perimeter of
the brake drum with a mallet. If the wheel now spins free, repeat the
adjustment. Once you have them so that hitting the brakes doesn't change
the drag, you have the shoes centered. Back the adjusters off two or
three flats, until you can just feel the shoes drag as you turn the wheel.
Now, adjust the parking brake cable to desired feel.
Oh, first thing is to make sure you have the shoes installed correctly.
The lining is offset on the shoe. They go on such that the lining offset
is in the direction of wheel spin. i.e. the "bare" spot on the shoe
goes at bottom rear and top front. This is not the American way. If they're
installed wrong, they will never adjust right.
>Many, many other things
Lots of things I would have commented on, but since they're all now old
news, I'll let them be. Except... I'd better not catch any clown attempting
to toss *my* Mini!! :>
Randy (the over opinionated wrench)
randy@taylor.uucp
P.S. Can anyone point me to the mentioned needle software, and is it in
source form? That's something I wouldn't mind porting over to my platform.
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