Hot rodding the HEI distributor
(Add, format photos, text.) |
m (→Example of a "typical" ignition advance curve: Edit text.) |
||
| Line 147: | Line 147: | ||
Be aware that if the carb or induction system is overly restrictive there may be vacuum developed at wide open throttle. This can cause the vacuum advance to add advance when it's not wanted. To be sure this isn't happening, a vacuum gauge can be duct taped to the base of the windshield so it can be viewed (preferably by a passenger) while the vehicle is put through various driving conditions. You will want to note that there's not enough vacuum at WOT to cause the vacuum advance to work. | Be aware that if the carb or induction system is overly restrictive there may be vacuum developed at wide open throttle. This can cause the vacuum advance to add advance when it's not wanted. To be sure this isn't happening, a vacuum gauge can be duct taped to the base of the windshield so it can be viewed (preferably by a passenger) while the vehicle is put through various driving conditions. You will want to note that there's not enough vacuum at WOT to cause the vacuum advance to work. | ||
| − | ==Example of a "typical" ignition advance curve== | + | ==Example of a "typical" performance ignition advance curve== |
A typical advance curve for a mild camshaft and compression ratio correctly matched to the cam will look something like this: | A typical advance curve for a mild camshaft and compression ratio correctly matched to the cam will look something like this: | ||
| − | 14 degrees initial advance | + | *14 degrees initial advance |
| + | *20 degrees centrifugal | ||
| + | *16 degrees vacuum advance | ||
| + | the above equals 50 degrees total advance including vacuum advance) under light throttle cruse/high vacuum conditions. Using an adjustable vacuum advance unit, the vacuum advance can be adjusted for what vacuum the vacuum advance falls out and tips in. | ||
| − | If you are in the 45-55 degrees range | + | If you are in the 45-55 degrees range (about 50 degrees is fine in most cases) of total advance, you’re in the ballpark. Each engine is different and what works for one engine might be a little different than what works for another engine. |
| + | |||
| + | '''NOTE-''' "Total advance" means the amount of initial plus the mechanical advance; the vacuum advance is considered to be separate from total advance in most discussions on ignition timing curves, etc. | ||
==Installation tips== | ==Installation tips== | ||
Your Privacy Choices