How do I figure out what the timing should be?
#1
10-21-2011, 04:01 PM
How do I figure out what the timing should be?
I have a 1969 Camaro with SB 350 and several aftermarket parts on it. I'm trying to figure out what the timing should be set to but can't seem to find any formulas or information out there for this. Does anyone know how to calculate what the timing should be for a small block 350? I tried setting it to the original factory 4 degree and the engine won't even run at that setting. I've just advanced it to where it runs reasonably well but I'm worried it may be too far advanced or not enough. Can anyone help me?
#2
10-21-2011, 04:18 PM
Join Date: Oct 2007
Location: The 'Burbs of Chicago
Posts: 18,306
Yeah, you can't go "by the book" with a modified engine. I'd start at 8-10 before tdc and see/hear how she runs. Use your ears, and listen for any octane knock (marbles) while you put the engine under a load, running it hard. If none, advance it a couple degrees more at a time and run it again. If you have pinging, then back the timing off a couple degrees. Going max advance right before ping has always worked well for me. Once you have a trained ear, it'll be easy to do.
#3
10-21-2011, 04:28 PM
^ As above, listen to the beans rattling around in a coffee can. There is no magic formula.
Without using a dyno you will have to use the trial and error method. Keep advancing the spark till you get a slight ping under full throttle, then back off 1 or 2 degrees. This will give you a ball park figure, and it won't be optimal, but it will keep you from damaging the engine. You will then have to experiment with the timing curve to find at what RPM full advance should be reached, and set the proper initial advance but still maintain the same total advance. If using a dyno, manually adjust the distributor for max power every 500 RPM and record the advance. Then adjust the timing curve as close as possible to the dyno results.
Or if you are just interested in drag racing, forget about the initial advance and just adjust the total advance for best 1/4 mile times. Check the plugs after each run & make sure there is no auminum specks deposited on the electrodes, which indicates you are burning the pistons. If that happens go to colder plugs, or richer mixture, or less timing or any combination.You still need to experiment.
Without using a dyno you will have to use the trial and error method. Keep advancing the spark till you get a slight ping under full throttle, then back off 1 or 2 degrees. This will give you a ball park figure, and it won't be optimal, but it will keep you from damaging the engine. You will then have to experiment with the timing curve to find at what RPM full advance should be reached, and set the proper initial advance but still maintain the same total advance. If using a dyno, manually adjust the distributor for max power every 500 RPM and record the advance. Then adjust the timing curve as close as possible to the dyno results.
Or if you are just interested in drag racing, forget about the initial advance and just adjust the total advance for best 1/4 mile times. Check the plugs after each run & make sure there is no auminum specks deposited on the electrodes, which indicates you are burning the pistons. If that happens go to colder plugs, or richer mixture, or less timing or any combination.You still need to experiment.
Last edited by z28pete; 10-21-2011 at 04:52 PM.
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