From: John De Armond
Newsgroups: misc.rural
Subject: Re: Why do we park manual tranny vehicles in reverse?
Date: Thu, 17 Nov 2005 01:33:36 -0500
Message-ID: <dm8on1pkke9ubr09m1mj65uev3hajt2vr0@4ax.com>

On 16 Nov 2005 19:21:14 -0800, "Harry K" <turnkey4099@hotmail.com>
wrote:


>> we don't. When parking facing downhill, put it in first.
>> When parking facing uphill, put it in reverse.  You want the
>> lowest gear ratio for maximum compression braking.  Turning
>> an engine backwards (engine off, of course!) requires little
>> effort.
>
>Huh??  First time I heard that.  Shouoldn't make any difference at all
>since all valves, gears etc just rotate backward, they don't quit
>working.

Yup.  In fact, you can start and run a car engine in reverse by
holding the carb open (so the "exhaust" isn't restricted) and feeding
a little gasoline or propane into the open exhaust manifold, then
bumping the car backwards or forwards while in reverse.  The engine
won't run very well because the spark is WAY retarded but it WILL run.
I'd hate to think how many hundreds of dollars I've taken off poor
unsuspecting, uh, targets with bets about this.  With a little
mouthing, you can get the more know-it-all types to bet a couple
hundred dollars or more :-)

>Oddly, my brother, who was a professional mechanic (ford garage)
>thought, you couldn't coast start a car in reverse (coasting backward)
>- it works just fine.
>
>As for my F150 I park in the gear I parked in, 1st (granny) or 2nd
>whichever, or reverse.
>
>As for 'old customs die hard'  parking in reverse in the old 30s and
>earlier 3 spd vehicles made sense in that the shifter was on the floor
>and it had to be 'up' to be out of the way.  Reverse was the best
>choice as the only other one was 2nd - very poor for parking on  a
>hill.

Bingo.  I think you've hit the nail on the head.  Combine poor brakes
with the parking brake handle that took two gorillas on steroids to
pull and you have the need for compression braking.

John

From: John De Armond
Newsgroups: misc.rural
Subject: Re: Why do we park manual tranny vehicles in reverse?
Date: Thu, 17 Nov 2005 13:12:09 -0500
Message-ID: <7ohpn1to7ntvddgbof7r4sijvjg095fnv9@4ax.com>

On 17 Nov 2005 06:37:11 -0800, "Harry K" <turnkey4099@hotmail.com>
wrote:


>> Yup.  In fact, you can start and run a car engine in reverse by
>> holding the carb open (so the "exhaust" isn't restricted) and feeding
>> a little gasoline or propane into the open exhaust manifold, then
>> bumping the car backwards or forwards while in reverse.  The engine
>> won't run very well because the spark is WAY retarded but it WILL run.
>> I'd hate to think how many hundreds of dollars I've taken off poor
>> unsuspecting, uh, targets with bets about this.  With a little
>> mouthing, you can get the more know-it-all types to bet a couple
>> hundred dollars or more :-)


>Now that is something I hadn't heard but it does sound logical.   Don't
>think I will be trying it though.  You could have collected a few bucks
>of of me.

:-)

You've probably heard a car engine run backward and didn't realize it.
When you turn a carbureted engine off from a high idle, hear it coast
down, clatter a couple of times and then "diesel" while making a loud
hiss out the air cleaner, you've just heard it run backwards.  Good
mixture got pumped into the exhaust during the coast-down.  When the
thing clattered (detonated), it hit off backwards. The loud hiss was
the "exhaust" passing back through the carb and out the air cleaner.
Ignition came from the glowplug effect of something hot in the
combustion chamber.

I observed the fan turn backward during the hiss, which is what
inspired me to the scheme for relieving some good ole boys of money
they didn't really need :-)

From: John De Armond
Newsgroups: misc.rural
Subject: Re: Why do we park manual tranny vehicles in reverse?
Date: Thu, 17 Nov 2005 13:16:22 -0500
Message-ID: <b0ipn1dnm59ln9h27rijusj9ek316ghpfn@4ax.com>

On 17 Nov 2005 15:42:40 GMT, Dave Hinz <DaveHinz@spamcop.net> wrote:

>On Thu, 17 Nov 2005 01:33:36 -0500, Neon John <no@never.com> wrote:
>
>> Yup.  In fact, you can start and run a car engine in reverse by
>> holding the carb open (so the "exhaust" isn't restricted) and feeding
>> a little gasoline or propane into the open exhaust manifold, then
>> bumping the car backwards or forwards while in reverse.  The engine
>> won't run very well because the spark is WAY retarded but it WILL run.
>> I'd hate to think how many hundreds of dollars I've taken off poor
>> unsuspecting, uh, targets with bets about this.  With a little
>> mouthing, you can get the more know-it-all types to bet a couple
>> hundred dollars or more :-)
>
>Speaking from direct personal experience, you can get an Allis Chalmers
>"B" running with the engine backwards.  One forward gear, 3 reverse...
>I found that out as a result of an engine-braking experiment gone wrong.
>Pretty high in pucker factor for a bit, given the hill involved and the
>mental "What the hell is going on here" moment.

 :-)

Back in my younger, wilder days when I raced motorcycles, I'd often
put on a trick riding exhibition at the local track at half-time.  One
of my stunts was to roll up the big jump in front of the stands, kill
the engine, then roll backwards on my 2-stroke motorcycle, pop the
clutch and crank it in reverse.  A 2-stroke runs just fine in reverse,
sucking through the carb and exhausting normally.  The timing is
retarded so it doesn't make much power but it runs just fine.  I'd
then ride around the track in reverse while facing forward and
steering using two little mirrors I'd attached to my helmet visor.

Riding backwards, facing forward was probably the hardest stunt I ever
learned to do.  I STILL have tender spots to prove it!

John

From: John De Armond
Newsgroups: misc.rural
Subject: Re: Why do we park manual tranny vehicles in reverse?
Date: Thu, 17 Nov 2005 14:43:57 -0500
Message-ID: <4anpn1pqfvc85qdsl2glcstqpjb792tva0@4ax.com>

On 17 Nov 2005 17:41:19 GMT, Dave Hinz <DaveHinz@spamcop.net> wrote:

>On Thu, 17 Nov 2005 15:42:53 GMT, Gil Faver <Rowdy'sboss@ND.com> wrote:
>>
>> "Dave Hinz" <DaveHinz@spamcop.net> wrote in message
>> news:3u3mhfFv4hl4U3@individual.net...
>
>>> In what universe is that true?
>
>> well, I can clarify.  for a loose engine, it can be turned
>> by hand backwards easier than it can be turned by hand
>> forward.  For a stiff engine, probably can't be turned by
>> hand at all!
>
>I'm not seeing it based on what I know about valve timing.

I've noticed that even on an engine on the stand without any plugs. My
SWAG is that it has to do with the piston pin offset and maybe the cam
chain tensioner.

John

From: John De Armond
Newsgroups: misc.rural
Subject: Re: Why do we park manual tranny vehicles in reverse?
Date: Thu, 17 Nov 2005 15:06:04 -0500
Message-ID: <3gopn19pv3nv0oevrb6epl8rk5aru3ao8k@4ax.com>

On 17 Nov 2005 19:50:42 GMT, Dave Hinz <DaveHinz@spamcop.net> wrote:

>On Thu, 17 Nov 2005 14:43:57 -0500, Neon John <no@never.com> wrote:
>> On 17 Nov 2005 17:41:19 GMT, Dave Hinz <DaveHinz@spamcop.net> wrote:
>
>>>I'm not seeing it based on what I know about valve timing.
>
>> I've noticed that even on an engine on the stand without any plugs. My
>> SWAG is that it has to do with the piston pin offset and maybe the cam
>> chain tensioner.
>
>Hm, most of the engines I've dealt with have subtle wrist pin offsets.
>I'm not sure how a chain tensioner would care which direction you're
>turning?  Prolly a few dozen ways to do it, though, and I've seen
>exactly two.

On an overhead cam engine, the tension side generally has a fixed
rubber coated slipper while the slack side has a hydraulically
actuated shoe that doesn't touch the chain much without oil pressure.
Turning the engine in the normal direction has the tensioned chain
tight up against the curved shoe.  Turning it the other way has the
tension side not touching anything.

yeah, the pin offset is small but then, so is the difference in
turning torque as measured by hand.  A few ft-lbs at most.  Like I
said, just my SWAG.

John