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burnin oil · 02-10-2021, 08:40 PM

To limit all timing confusion. The curve is important but the max timing is the critical point. You need to get the full timing weight advance and adjust the dizzy so it falls between 34-36 degrees for a stock head ( not vortec) motor. This is their happy place. From there you can let the idle fall where it pleases. If the idle timing (ie base timing) is not to your liking then a recurve is needed. If max timing and base timing are good to go then feel free to play with the timing wieght springs to dial it in. Odds are you will end up with either the factory spring or the kits heavy spring and a medium spring.

Beyond the above you have no control of the timing curve other than changing wieghts or making limiters in the advance plate for the timing wieghts or a different vac advance canister. The vav advance canister part number does give clues on the amount of vacuum needed to get a set amount of advance. Crane cams makes a limiter to adjust the vac advance but I never had much luck with it. The problem was the different cans has different internal springs and diaphragms so the vac canisters advance wasn't linear. They work somewhat but it's easier to just buy another can that does what you want. Changing cans also makes the advance smoother versus the crane limiter.

PS. Stop buy the house and I will teach you more than you ever wanted to know about anything with wheels. Besides learning a good mentor is paramount in this hobby. Find someone who will explain everything before even touching a wrench and you will be light years ahead in the game. Honestly 20 years of self learning can be surpassed in a 15 minute conversation with a car guy. Those of us who have done this for a lifetime forget the learning curve when talking to the new guy. We just need grounded from time to time. We are here to help each other and learn from time to time. Perspective is also a great teacher.

02-10-2021, 08:40 PM	#52
burnin oil Registered User Join Date: Jan 2013 Location: Eastern TN Posts: 1,921	Re: Timing & Gas Milage To limit all timing confusion. The curve is important but the max timing is the critical point. You need to get the full timing weight advance and adjust the dizzy so it falls between 34-36 degrees for a stock head ( not vortec) motor. This is their happy place. From there you can let the idle fall where it pleases. If the idle timing (ie base timing) is not to your liking then a recurve is needed. If max timing and base timing are good to go then feel free to play with the timing wieght springs to dial it in. Odds are you will end up with either the factory spring or the kits heavy spring and a medium spring. Beyond the above you have no control of the timing curve other than changing wieghts or making limiters in the advance plate for the timing wieghts or a different vac advance canister. The vav advance canister part number does give clues on the amount of vacuum needed to get a set amount of advance. Crane cams makes a limiter to adjust the vac advance but I never had much luck with it. The problem was the different cans has different internal springs and diaphragms so the vac canisters advance wasn't linear. They work somewhat but it's easier to just buy another can that does what you want. Changing cans also makes the advance smoother versus the crane limiter. PS. Stop buy the house and I will teach you more than you ever wanted to know about anything with wheels. Besides learning a good mentor is paramount in this hobby. Find someone who will explain everything before even touching a wrench and you will be light years ahead in the game. Honestly 20 years of self learning can be surpassed in a 15 minute conversation with a car guy. Those of us who have done this for a lifetime forget the learning curve when talking to the new guy. We just need grounded from time to time. We are here to help each other and learn from time to time. Perspective is also a great teacher.