pataky@gymble.UUCP (Bill Pataky) (10/17/85)
Can someone explain to me what factors are involved in selecting the
correct carburetor jets for a particular configuration of a particular engine?
I own an '80 Spitfire (USA market) with a 32/36 Weber Carb. There are no
emission controls on this engine, and between the addition of the weber and
the removal of the Emission controls I have significantly improved the engine's
power output over the original 53 (whopping) hp. The car was also marketed in
Europe with the same engine with no emissions devices and a different cylinder
head giving it significantly more hp with a 9.5:1 comression ratio versus the
USA market's 7.5:1 compression ratio. I have the oppurtunity to have a friend
in Europe buy a European cylinder head and bring it over. My question arises:
should I re-jet the carb when I get the new head?
After thinking about it, I came up with 2 factors that determine jetting.
One would be the expected operating speed of the engine, and the other would be
the displacement of the engine. Since I am not changing any of these, I would
assume that I would not have to re-jet the carb. Am I correct?
Thanks...
Bill Pataky
Parallel Processing Lab
University Of Maryland
pataky@gymble.umd.eduksbszabo@watvlsi.UUCP (Kevin Szabo) (10/18/85)
You have left out a number of factors... one of which is the cooling effect of the gasoline. By running rich the air/fuel mixture is cooled and stays dense. Hence the total amount of air/fuel that is introduced to the combustion chamber will be greater and more power will be generated. Too much fuel and you start washing the oil off the cylinder walls. I suggest you pick up a short book on carburation from your local library or bookstore. Most of the major factors will be discussed. Kevin -- Kevin Szabo' watmath!watvlsi!ksbszabo (U of W VLSI Group, Waterloo, Ont, Canada)