Determining top dead center
From Crankshaft Coalition Wiki
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==Rebuilt dampers== | ==Rebuilt dampers== | ||
| − | One noted place to buy a rebuilt damper/balancer is [http://www.damperdoctor.com/ Damper Doctor]. They disassemble stock, OEM production dampers, clock the hub to the inertia ring and reassemble the unit with new elastomeric material pressed together under tremendous hydraulic pressure. An 8" damper for a 350 Chevy can be had for a mere $32.95 (ca. 2012) | + | One noted place to buy a rebuilt damper/balancer is [http://www.damperdoctor.com/ Damper Doctor]. They disassemble stock, OEM production dampers, clock the hub to the inertia ring and reassemble the unit with new elastomeric material pressed together under tremendous hydraulic pressure. An 8" damper for a 350 Chevy can be had for a mere $32.95 (ca. 2012). |
The option is a used damper/balancer that may be clocked worse than the one you have or an aftermarket damper/balancer that will cost more money and may not have been correctly machined on the inner hub diameter. Some of these offshore (Chinese) dampers being sold are bored either oversize or undersize for the production crank snout diameter. The damper/balancer hub MUST BE A SNUG PRESS-FIT on the crank in order to properly transfer harmonics from the crankshaft to the damper/balancer hub and on to the inertia ring, where harmonics are dissipated. | The option is a used damper/balancer that may be clocked worse than the one you have or an aftermarket damper/balancer that will cost more money and may not have been correctly machined on the inner hub diameter. Some of these offshore (Chinese) dampers being sold are bored either oversize or undersize for the production crank snout diameter. The damper/balancer hub MUST BE A SNUG PRESS-FIT on the crank in order to properly transfer harmonics from the crankshaft to the damper/balancer hub and on to the inertia ring, where harmonics are dissipated. | ||
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If using a camshaft with more duration, you may want to increase the ignition timing lead at the crank and limit the centrifugal advance in the distributor to achieve your total ignition timing. Some distributors, like those sold by MSD, use different bushings to control the ''amount'' of mechanical advance. The '''rate''' of mechanical advance is tailored by changing the springs and/or centrifugal weights. Usually just spring changes are all that is needed. If working on a GM HEI, the original weights are almost always a better choice than the weights sold in the various advance curve kits available from Mr. Gasket, Crane, Summit, Moroso, etc. | If using a camshaft with more duration, you may want to increase the ignition timing lead at the crank and limit the centrifugal advance in the distributor to achieve your total ignition timing. Some distributors, like those sold by MSD, use different bushings to control the ''amount'' of mechanical advance. The '''rate''' of mechanical advance is tailored by changing the springs and/or centrifugal weights. Usually just spring changes are all that is needed. If working on a GM HEI, the original weights are almost always a better choice than the weights sold in the various advance curve kits available from Mr. Gasket, Crane, Summit, Moroso, etc. | ||
| − | If you are using a radical cam and/or a converter that allows the engine RPM to come up past where you would normally limit centrifugal advance (about 2800 rpm), you may want to modify the distributor so that centrifugal advance is locked out and put your total amount of ignition advance in at the crank. Of course, the engine will not want to crank against this much ignition lead, so you will want to install a momentary switch in the wire going to the "+" terminal of the coil to disable the coil while you crank the engine. Once the engine is spinning, release the switch and the engine will fire normally. | + | If you are using a radical cam and/or a converter that allows the engine RPM to come up past where you would normally limit centrifugal advance (about 2800 rpm), you may want to modify the distributor so that centrifugal advance is locked out and put your total amount of ignition advance in at the crank. Of course, the engine will not want to crank against this much ignition lead, so you will want to install a momentary switch in the wire going to the "+" terminal of the coil to disable the coil while you crank the engine. Once the engine is spinning, release the switch and the engine will fire normally. |
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