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#1 |
Senior Member
Join Date: May 2010
Location: Chester Vt
Posts: 8,985
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Over the past few years Richard and I have used his engine as a test bed for out economy tests. By using an A/F meter and a GM distributor, we tried numerious combinations of carburetor jetting and Ignition advance cueves. The explination I gave in another post was in error and richard was kind enough to make the following corrections. OK Dummy, here's the right way to do it.
"If you're running a converted Chevy distributor from Classic Ignition or Bubba or some other source forget about setting engine-off static advance with a light bulb. Both static and initial advance are interesting to know but what's really important is maximum advance, both mechanical and mechanical+vacuum if you're into vacuum... and you should be. This method works great with points, HEI, and MSD ignition. All you need is a simple paper degree strip glued to your pulley and a timing light with an inductive pickup. You can make the degree strip with your computer. Disconnect the vacuum and plug the rubber tube. Remove the distributor springs so you don't need to rev the engine to get maximum mechanical advance. With the engine at idle, set the maximum mechanical advance where you want it when it's all in; 20-22° is a good place to start. Let the initial fall where it may. You may want to raise or lower your idle speed at the carburetor. If you don't have vacuum advance, you're done. Replace the springs, double-check everything with your timing light, and go for a ride. To see or set the maximum mechanical+vacuum advance, reconnect the vacuum with the springs still out. At idle, the engine is making high vacuum, so it's like checking the vacuum advance at cruise. If you're using an adjustable vacuum canister, you can set it where you want it. 8° goes well with the 20-22° of mechanical, giving you a TOTAL advance of 28-30°. Then put back the springs. If for some reason you want to see what the initial (not static) advance is (before any mechanical advance kicks in), disconnect the vacuum, remove the weights then put back the springs. Now, at idle, you can read the initial advance. Reinstall the weights, reconnect the vacuum, double-check everything with your timing light, and go for a ride. You can increase or decrease the range between initial and maximum advance by changing the advance-stop bushing in the distributor. These bushings are easy to buy or make." -------------------- We make changes to find the optium, so far we like this one. Just remember, these numbers work for his engine. |
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