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ChadS
04-12-2006 15:14:30
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Re: ih flyweights in reply to Custom King, 04-10-2006 19:10:25
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GM had quite a few different advance curves for different engines and styles. Different weights, springs etc etc.Im not sure on the 4 cyl engines but,,, HEI distributors were a 1 wire hook up, 2 with a tach, And a vaccum advance, later HEI versions had the plugs away from the cap and came out of the side, You find these on the older Chevy V6's straight 6's and V8. Some of them had advances built in, most were solid and computer contolled. If this is the style you have, HEI style with the 2 plugs, and a mechanical advance, they are good up to 40 degrees advance with the mechanical. Later, the new style distributors doesn't have mechanical advances, they were ran by the computer to control the timing. Each distributor model has a set advance curve, you can look up the specs on your GM distributor to see how far the mechanical advance moves the timing. If you have altered this distributor to another engine, and then running the engine beyond the recommended specs,,, if you have added a cam, big carb, different ratio rockers to run high rpm VS slower OEM speeds, Base timing is difficult to estimate with out putting the engine on a dyno, or somehow work the engine long enough to be able to make an adjustment to record. you cant go off the book specs, thats for sure! 3 ways to go about this, Tune it by ear, run it, if you like its performance, put a timing light on it and record the reading, tweek from there,, its alot of work,, test and tune, test and tune... Or put it on a dyno, the engine not the tractor, no tractor, 540 pto dyno would be safe turning that fast, even at 1000 on the 1000 side of the dyno. if your brave and the dyno operator is brave, you can get an idea from that by reading the HP at the rpm range and look for increases in HP, then become steady, I dont recommend this at all,,,, but would work. OR, get ya that timing control addition to your MSD, get it running best to ear, or on the track, and dial it in from there to get your base timing recorded for your engines combination of custom parts to enhance performance. You will feel it in the seat while on the track if the timing is off, HP will go up if its down. Thats the best I can do without knowing exactly what you have and with the info you have provided. Auto distributors are good for high rpm and have enough timing in the advance. Now, as fas as the coil is concerned, bout any good 12 volt coil will work wit hyour MSD, yeah there is one listed in the instructions not to use, but the rest are open season. The MSD uses the full power of the coil,zaps the lugs about 3-5 times more than just the one time spark from stock, where points use maybe 1/3 of the potential energy. Lighter advance weights and different spring tensions help with throttle responce upon acceleration. Timing has to be altered along the route upon acceleration to help out the rpm increase. Other wise it will be only relying on the carb, and the advance timing in stock form to help rev up a more than stock compression, faster accelerating engine. The engine will be slow upon revving up. That helps get the rpm up to fast idle ASAP. If you think its a bit lazy, and lighter weights are available, try them out, then tune in the spring tension to really tune it in. If the base timing is set well enough, but it pops thru the carb upon acceleration after the changes, then the advance is working to quickly and too much so stiffen the spring tension on the light weights. To be more precise, more info, what are you driving? Chad
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