Right off the bat: if your car has ESA, go get rid of it, then come back and start reading. This will be of no use to the Lean Burn crowd.
This is the easiest, most enjoyable, and probably safest way to set your timing that I've found. Most accurate? No, but you won't hurt the car and you'll probably pick up some mileage and power along the way. As is always the case, you should check your ignition for any signs of wear or faults and repair them before you start, and a fresh set of plugs never killed anyone unless they tried to eat them. A full tank of gas is a good idea too, since it's weight and we're using load to set the timing. Use the gas you normally use; upping to premium or putting in octane boost is a really bad idea if you normally fill up on 87 octane. Be realistic. Your pistons will thank you.
First things first: You still need a timing light for this. A dial-back is best because there's a good chance you may go off the end of your timing tab, depending on your combination. There's really no good way around it unless you have an extremely delicate touch when twisting your distributor. You're also going to need a really big hill. Long & steep is good, longer & steeper is better yet. Try and find one out of the way with a highway-type speed limit. Now, realistically gauge a worst-case scenario for how you're going to use the car. I'm not married, don't have kids, and don't own a trailer or anything with a hitch. I travel light, I pound my cars mercilessly... and I have the third thing needed for this test: a Big Fat Friend. My friend's name is Jeff and he goes about 390lbs. He's helped me set my timing in the past, and always enjoyed it, being all too aware of why he's in the car with me. He's the fattest f&@# I know. :icon_biggrin:
Start out with your base timing. Unplug your vacuum advance and plug the port on the carb, then connect your timing light. If you know your car's factory base timing, that's good. If you don't, no big deal. Generally, a good start is about 4-6° more advanced than factory timing. If you don't know the number, start at 8° BTDC. Even if your factory timing was supposed to be 0° (TDC) you're not gonna hurt the engine so don't worry. While you've got the hood open, take off the bulkhead weatherstrip in front of the heater vents if you can do it without damaging the strip or its fasteners. If you really want to get serious, remove the hood pad too. It is not critical to remove either, but it helps.
Wedge your BFF into the passenger's seat. This may require a crowbar, plunger, or tossing a Twinkie onto the driver's seat from the passenger's door. Strap him in; if you're really good at choosing your helper, US Federal Law requires that seat-belt extenders be provided at no charge by your servicing dealer. I'm not kidding.
Drive out to your chosen incline. Stop the car once you're on the hill, right at the start. Roll up the windows, turn off the radio, and turn your HVAC controls to a comfortable temperature, AC on if you have it. Set the air to blow either out the defroster, or preferably the dash vents, but keep the blower motor at its lowest switch position ("off" if it won't stop the AC).
OK, right now you're asking yourself, "What the hell is with removing the hood pad & cowl seal and running the HVAC only through the dash or defrost vents?!" Well, what we're doing here is listening for spark knock... so think of your HVAC ductwork as a big stethoscope. Removing the weatherstrip opens up the end of the stethoscope to the engine bay, and removing the hood pad keeps it from dampening the sound. You want to hear detonation ASAP; this makes it a little easier. As I said previously, it's not critical. You still want the AC on for the additional engine load, though. Back to tuning...
Put the car in gear and beat it like a rented mule. Foot absolutely to the floor., manually upshifting it if you're prone to such behavior (or have a manual trans, duh). Pretend you're in a life-or-death drag race. Halfway through second gear is plenty; that upshift is nice if you can get it legally. Otherwise, just take it as far as you can without breaking the law. Tell Chunky Love to quit screaming, and listen closely for spark knock. Odds are you won't hear any, but if you do let off the throttle immediately.
If you heard detonation, back off the timing 1° and re-test. Repeat in 1° increments until you hear no detonation at any point. Back off an extra degree for a safety margin (bad gas, altitude) if you like. You're done. Go get Rotundo the Most Portulent a Double Whopper value meal and call it a day.
If you did not hear detonation, increase the timing by 2° and retest. Still no detonation? Give it another 2°, and repeat both testing and 2° increases in advance until you do. Back the timing off 1° and run it again. Chances are it's good. If not, one more degree of retard will be optimal since you're back at the same level you were before the last 2° increase, when it didn't knock. If it makes you feel better, take it 1° below that to account for bad fuel, altitude, etc. You have now completed your tuning for the day. Buy Gravitus Maximus a dozen Bavarian cremes and a chocolate malt for his time. Reinstall the cowl seal and hood insulation if you removed them.
If your combination is 100% stock except for the ignition system, chances are this won't take long. You'll probably wind up around 6°-8° over stock, maybe less. If you've got an aftermarket cam and carb, free-flowing exhaust, etc. this could take awhile. Consider the curious case of my Tin Indian Ram Air III. Factory base timing on that car was 9° BTDC. By the time I was done, it was at a staggering 26° BTDC with no detonation but it absolutely refused to start warm. I backed it off to 24°--still rather astounding--and installed a 1,100CCA 31-series semi-truck battery... and got a lot of jumpstarts in warm weather. To me, it was worth the hassle. I never expected that car to be as fast as it was.
If you go back and modify your ignition or engine after you've done this, such as a new coil/module, lighter advance springs, new camshaft, head work, etc. you should re-time the car in the same way, starting with the current timing and testing from there. Yes, there are more-accurate ways to configure your timing including a bitchin' recurve of your distributor (good luck finding a local place that can do it anymore). Better ways? Well, not from the fun standpoint, and once you've done this you've essentially guaranteed detonation won't be an issue in the future.
This is the easiest, most enjoyable, and probably safest way to set your timing that I've found. Most accurate? No, but you won't hurt the car and you'll probably pick up some mileage and power along the way. As is always the case, you should check your ignition for any signs of wear or faults and repair them before you start, and a fresh set of plugs never killed anyone unless they tried to eat them. A full tank of gas is a good idea too, since it's weight and we're using load to set the timing. Use the gas you normally use; upping to premium or putting in octane boost is a really bad idea if you normally fill up on 87 octane. Be realistic. Your pistons will thank you.
First things first: You still need a timing light for this. A dial-back is best because there's a good chance you may go off the end of your timing tab, depending on your combination. There's really no good way around it unless you have an extremely delicate touch when twisting your distributor. You're also going to need a really big hill. Long & steep is good, longer & steeper is better yet. Try and find one out of the way with a highway-type speed limit. Now, realistically gauge a worst-case scenario for how you're going to use the car. I'm not married, don't have kids, and don't own a trailer or anything with a hitch. I travel light, I pound my cars mercilessly... and I have the third thing needed for this test: a Big Fat Friend. My friend's name is Jeff and he goes about 390lbs. He's helped me set my timing in the past, and always enjoyed it, being all too aware of why he's in the car with me. He's the fattest f&@# I know. :icon_biggrin:
Start out with your base timing. Unplug your vacuum advance and plug the port on the carb, then connect your timing light. If you know your car's factory base timing, that's good. If you don't, no big deal. Generally, a good start is about 4-6° more advanced than factory timing. If you don't know the number, start at 8° BTDC. Even if your factory timing was supposed to be 0° (TDC) you're not gonna hurt the engine so don't worry. While you've got the hood open, take off the bulkhead weatherstrip in front of the heater vents if you can do it without damaging the strip or its fasteners. If you really want to get serious, remove the hood pad too. It is not critical to remove either, but it helps.
Wedge your BFF into the passenger's seat. This may require a crowbar, plunger, or tossing a Twinkie onto the driver's seat from the passenger's door. Strap him in; if you're really good at choosing your helper, US Federal Law requires that seat-belt extenders be provided at no charge by your servicing dealer. I'm not kidding.
Drive out to your chosen incline. Stop the car once you're on the hill, right at the start. Roll up the windows, turn off the radio, and turn your HVAC controls to a comfortable temperature, AC on if you have it. Set the air to blow either out the defroster, or preferably the dash vents, but keep the blower motor at its lowest switch position ("off" if it won't stop the AC).
OK, right now you're asking yourself, "What the hell is with removing the hood pad & cowl seal and running the HVAC only through the dash or defrost vents?!" Well, what we're doing here is listening for spark knock... so think of your HVAC ductwork as a big stethoscope. Removing the weatherstrip opens up the end of the stethoscope to the engine bay, and removing the hood pad keeps it from dampening the sound. You want to hear detonation ASAP; this makes it a little easier. As I said previously, it's not critical. You still want the AC on for the additional engine load, though. Back to tuning...
Put the car in gear and beat it like a rented mule. Foot absolutely to the floor., manually upshifting it if you're prone to such behavior (or have a manual trans, duh). Pretend you're in a life-or-death drag race. Halfway through second gear is plenty; that upshift is nice if you can get it legally. Otherwise, just take it as far as you can without breaking the law. Tell Chunky Love to quit screaming, and listen closely for spark knock. Odds are you won't hear any, but if you do let off the throttle immediately.
If you heard detonation, back off the timing 1° and re-test. Repeat in 1° increments until you hear no detonation at any point. Back off an extra degree for a safety margin (bad gas, altitude) if you like. You're done. Go get Rotundo the Most Portulent a Double Whopper value meal and call it a day.
If you did not hear detonation, increase the timing by 2° and retest. Still no detonation? Give it another 2°, and repeat both testing and 2° increases in advance until you do. Back the timing off 1° and run it again. Chances are it's good. If not, one more degree of retard will be optimal since you're back at the same level you were before the last 2° increase, when it didn't knock. If it makes you feel better, take it 1° below that to account for bad fuel, altitude, etc. You have now completed your tuning for the day. Buy Gravitus Maximus a dozen Bavarian cremes and a chocolate malt for his time. Reinstall the cowl seal and hood insulation if you removed them.
If your combination is 100% stock except for the ignition system, chances are this won't take long. You'll probably wind up around 6°-8° over stock, maybe less. If you've got an aftermarket cam and carb, free-flowing exhaust, etc. this could take awhile. Consider the curious case of my Tin Indian Ram Air III. Factory base timing on that car was 9° BTDC. By the time I was done, it was at a staggering 26° BTDC with no detonation but it absolutely refused to start warm. I backed it off to 24°--still rather astounding--and installed a 1,100CCA 31-series semi-truck battery... and got a lot of jumpstarts in warm weather. To me, it was worth the hassle. I never expected that car to be as fast as it was.
If you go back and modify your ignition or engine after you've done this, such as a new coil/module, lighter advance springs, new camshaft, head work, etc. you should re-time the car in the same way, starting with the current timing and testing from there. Yes, there are more-accurate ways to configure your timing including a bitchin' recurve of your distributor (good luck finding a local place that can do it anymore). Better ways? Well, not from the fun standpoint, and once you've done this you've essentially guaranteed detonation won't be an issue in the future.
