Header design
(→Summary of header design principles) |
(→Argument for equal primary tube lengths) |
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[[Image:unequal.jpg|right|frame|Big block Chevy headers. Note how the driver's side rear tube (yellow) must be about 10"-12" shorter than the next tube (in red).]] | [[Image:unequal.jpg|right|frame|Big block Chevy headers. Note how the driver's side rear tube (yellow) must be about 10"-12" shorter than the next tube (in red).]] | ||
| − | In the header photograph to the right, the short primary tube would scavenge at a higher RPM and the long primary tube would scavenge at a lower RPM for the respective cylinder. Therefore the cylinder with the short tube will be running lean at low RPM and the long tube cylinder will be running lean at the high RPM and would require different jetting and timing than the others. How do you do that with a standard kettering distributor and a simple carburetor? That's why equal length is important: so you can tune your car. | + | In the header photograph to the right, the short primary tube would scavenge at a higher RPM and the long primary tube would scavenge at a lower RPM for the respective cylinder. Therefore the cylinder with the short tube will be running lean at low RPM and the long tube cylinder will be running lean at the high RPM and would require different jetting and timing than the others. How do you do that with a standard kettering distributor and a simple carburetor? That's why equal length is important: so you can tune your car. Not only do equal length tubes make the engine tuneable, but make more torque in the RPM range for which they were intended. |
=====Argument against equal primary tube lengths===== | =====Argument against equal primary tube lengths===== | ||
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