OT a little

Okay, this is for people familiar with carburetors, because I grew up in an age of fuel injection. I believe a few friends of mine picked up a habit not needed.
Before shutting off their vehicles, they will rev them up and just as it's coming back down shut the key off.
I'm not certain which is why I'm posting, but wasn't that more for carburated engines? Something about getting a little extra fuel in so it starts easier or something?
Seems it wouldn't do anything on a fuel injected engine.
Thanks, Tony
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It is of no benefit but it might put extra gas fumes into the manifold. They should be flooring the gas pedal (once before starting it) to close the choke (engine cold). I've tried the other method and saw only needless wear on the engine and wasted fuel.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Tony V." wrote:

It just wastes fuel really.
-- Regards Dan. 00 VX SS beast. 93 VP Exec V6 project car,
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If I remember it has something to do with when the engines were hand-crank started. If there was gas in there and it was compressed it would make it easier for the engine to start or something along those lines. Then along came electric starters and people still did that though they didn't need to and it's just kinda stayed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I can't imagine what benefit that would be likely to give on any engine..
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from snipped-for-privacy@nospamshaw.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Okay, just for the record. There are some engines where it is (or was) advisable to let the engine sit at idle for a few minutes before shutting them down. You did this to scavage the excess oil out of the engine (dry sump) so you had oil when you restarted the engine. But these were jet engines mounted in aircraft, not piston engines with a wet sump system. I think that everyone agrees that your friends have bought into an old myth that may have once had merit, but now serves no real purpose.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@webtv.net says...

Something wrong with your friends. On a carbed engine that would do nothing but waste fuel.
--
_________________________________________________________________
Dennis Smith
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tony V. wrote in alt.autos.gm

The reason for doing this is that if the timing is advanced a might too much, the car will diesel (or run on) after you turn the key off. It is caused by carbon deposits that get too hot and cause the car to keep sputtering for a few minutes after the key is turned off. The way to stop that is to give the car an extra shot of gas, which would either burn off the deposits, or flood them so that they cooled down enough that they would not ignite the gas. This was such a common problem with cars that had the rudimentary emission controls of the 70's and early 80's that manufacturers installed systems on the carbs to hold the throttle open when you turned off the engine. However, it wasn't much of a problem on the older cars.
Electronic fuel injection cured the problem, as the electronics would not allow fuel to flow.
Another reason that people revved their engines, usually people who had done some building on their engines, was that they liked the sound and wanted everyone else to hear it, just like they do today.
--
Dick #1349
Damn it . . . Don't you dare ask God to help me.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Dick C" wrote

Actually, it was the other way around. Most carbs in those days had anti-dieseling solenoids. They would not "open" up the throttle, they would close it down completely when you shut off the ignition. When you started those cars, you would pump the pedal a time or two, this would set the choke plate, and allow the anti-dieseling solenoid to open up the throttle plate to the normal idle position. Once you cut the ignition, the solenoid would lose power and retract, completely closing the throttle plate.
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
shiden_Kai wrote in alt.autos.gm

Yeah, close it. Been too many years since I have worked on a carburated engine.

--
Dick #1349
Damn it . . . Don't you dare ask God to help me.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Tony V." wrote

It won't do anything for any engine. But a lot of people do a lot of strange things with their cars because somewhere along the way, they picked up some bizarre rituals/habits about how they drive/start/shutoff/change oil....etc....
Most of it is nothing more then myths and legends. But interestingly enough, even myths and legends probably had some truth to them at one time.
Ian
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

About 40 years ago, when I was young and stupid, we'd do that and turn the key back on just before the engine stopped turning. Nice loud backfire. Thought it sounded cool. Later on, if you had loud pipes you had to rev it before shutting it off, again for the cool factor. I'm past that stage now...mostly.;-0 BTW, doing that will kill a turbo. H
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.