Why do people do this, was there a reason on old cars with carburettors. We have been having a discussion at work today as there are some that think there was a reason, so the car started first time, when restarted. Is this right and why was the reason, and then there are the rest of us that think it complete cr@p. Can anyone give some ideas or there thoughts that i can tell them when at work tomorrow.

Thanks very much, i look forward to reading your replys.

Luke

 

Because they think theyre cool

 

Have been told that this is harmfull as it leaves un-burnt fuel on the cylinders bore. Not sure why thats bad but it is!

Cookie

 

Blipping the throttle before turning the engine off helps nothing at all, infact it can leave un-burnt fuel in the combustion chamber hence the potential for back fire at start-up.

 

I was told that it left unburnt fuel in the combstion chamber which then washes oil out of the bores leading to more wear on startup.

 

With todays modern engines with injection and electronic ign. it is very bad practice but (I believe) 40/50 yrs ago it was recommended as it aided re-starting. My Dad did it and he was taught in the 40's. You need to go onto the VSCC site and ask them, or MG car club, or Austin Healey Club.

 

Looks like a trip to one of these websites then, the majority of us at work were saying the same that it just washes the bores down with fuel. Not good.

Thanks all

 

Also, blipping a turbocharged engine isn't the best of ideas as you're doing a hot shut-down so any oil pressure will drop like a stone as the engine stops but the turbo's still running down from a potentially higher speed than tickover speed - not good for lubrication properties especially if you haven't been off boost / on cool-down before blipping the throttle

 

Agreed,it applied to cars with carburettors that had the accelerator pump & discharge tube configuration.Weber carbs on early Fords for example.Blipping the throttle squirts a jet of fuel down the throat of the carb.Thats why the starting procedure on some early cars was to press the throttle two or three times before turning the ignition.Not needed on later cars with better cold start mechanisms.This would only lead to flooding them & all the associated problems with starting a flooded engine.

Blipping the throttle when switching off supposedly left extra fuel in the combustion chamber so that when next started it would act like an extra "choke" & richen the mixture.Although how much fuel would remain after washing down the oil on the wall of the bores & filtering past the piston rings is anybodies guess.Not to mention losses by evaporation from a hot engine.

Mark

 

just an interessting point, on our 1913 cadilac with a 6 litre :O 4 cylinder engine you have to put petrol into some little taps, open and then close them above each cyclinder.

and then crank it by hand if the b*tch doesnt want to start