In an earlier E-mail Barrett Revis had made comment regarding the jet size
and literally cooking your engine. To be honest, as most of you probably
know, the bigger the Main Jet the more gas that is burned. This can easily
be confirmed by the gas gauge and odometer as well as the spark plugs. If
they are burning BLACK the mixture is way to rich - or way to much gas. If
the plugs are burning light gray to WHITE the mixture is way to lean - not
enough gas. If the spark plugs are between a nice TAN and CHOCOLATE colour
you have hit the mixture right. To check this run the engine at highway
speed for several miles then push in the clutch and shut the engine off.
Coast to a stop and pull a couple of plugs to check the colour. Do not rely
on just one plug only make sure that you check at least two or them say No.
2 and No. 4 cylinder and even maybe No. 6 cylinder. Compare the plugs and
take sort of an average colour. If you are in the tan to chocolate range
pat yourself on the back and put the plugs back in. You won't get the
mixture much better than that. If the plugs are Dark Brown to Black go home
and put in a smaller jet then try again until you get the Tan to Chocolate.
If the plugs are light gray to white go to a bigger jet and try again.
Eventually you will get it right and you will see the improvement in your
gas mileage. If you are running rich you are not burning all the gas going
into the cylinder. What is not burned is going out the exhaust pipe and
adding to the air pollution problem for no good reason. If you have jetted
your carb right you will get peak performance, good mileage and still have
all the power you need. The one note is to pay attention to altitude as
this can and will have an effect based on the density of the air and you may
have to go up or down a jet size. This can again be determined by checking
the spark plugs.
Hope this has been of some help to those thinking of playing with jets or
looking to try and improve the mileage and or efficiency of their engines
Good Luck
Mac
52 Chev 1300
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