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LONGHAIR · 04-12-2008, 04:41 PM

While I realize that the 700r4/2.73 gear is a factory thing....that may very well be part of your fuel milage problem. It "sounds" like it would make sense to have the engine RPM as low as possible at highway speeds, but that is not always the case, especially with over-drive transmissions. "Lugging" the engine in an RPM range that is too low requires more throttle as well as the over-drive "searching" for the right gear are the results.
It sounds counter-intuitive, but a lower gear can take care of these problems.

As far as the original question, carb spacers are nearly impossible to judge w/o installing and testing. Height(thickness) and the center configuration can make for different results on the very same engine. Some like the 4-hole and others are better with an open center. Different thicknesses can work different too. Some engines don't show any improvement at all or may even get worse, others have measurable improvments in mileage and seat-of-the-pants driving. Testing on your engine, not your friend's recommendation, is the only way.

04-12-2008, 04:41 PM	#2
LONGHAIR just can't cover up my redneck Join Date: May 2004 Location: Columbus OH Posts: 11,414	Re: Carb spacers. pros/cons While I realize that the 700r4/2.73 gear is a factory thing....that may very well be part of your fuel milage problem. It "sounds" like it would make sense to have the engine RPM as low as possible at highway speeds, but that is not always the case, especially with over-drive transmissions. "Lugging" the engine in an RPM range that is too low requires more throttle as well as the over-drive "searching" for the right gear are the results. It sounds counter-intuitive, but a lower gear can take care of these problems. As far as the original question, carb spacers are nearly impossible to judge w/o installing and testing. Height(thickness) and the center configuration can make for different results on the very same engine. Some like the 4-hole and others are better with an open center. Different thicknesses can work different too. Some engines don't show any improvement at all or may even get worse, others have measurable improvments in mileage and seat-of-the-pants driving. Testing on your engine, not your friend's recommendation, is the only way.