Optimised timing curve, anyone plotted it?
Thread Starter
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
Optimised timing curve, anyone plotted it?
Ok so we try to set the timing so its around 36 degrees all in by say 2800 rpm but what about the points in between? I guess it should be a steady smooth curve so I wondered if anyone had plotted the 'optimum' curve?
Would help selecting the right springs etc for the distributor.
TIA.
Would help selecting the right springs etc for the distributor.
TIA.
Burning Brakes
Joined: Jul 2008
Posts: 990
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From: South Louisiana offshore, Gulf of Mexico
Thread Starter
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
Race Director
Joined: Jul 2004
Posts: 12,706
Likes: 329
From: Scottsdale Arizona
Paul,
To go with Pete's curve above, scroll down to page 4 of the attached MSD setup instructions to see various "curves.". I put it in quotes because they are pretty linear. Other than the starting point and finishing point, I'm not sure that there is much that you can do to alter the curve itself on a conventional system. I do know that there are programmable versions though I couldn't say how much difference these make.
http://www.jegs.com/InstallationInst...1/121-8516.pdf
To go with Pete's curve above, scroll down to page 4 of the attached MSD setup instructions to see various "curves.". I put it in quotes because they are pretty linear. Other than the starting point and finishing point, I'm not sure that there is much that you can do to alter the curve itself on a conventional system. I do know that there are programmable versions though I couldn't say how much difference these make.
http://www.jegs.com/InstallationInst...1/121-8516.pdf
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Optimized for what? Best power? Best economy? At what load?
The only way to define an "optimum" timing curve is to put the engine on a GOOD dynomometer and play with it for a few hours...finding the 'optimum' timing for specified conditions at many RPM settings throughout the engine's operating range and at some specified loading on the crank. Then, you can work for many hours whittling on distributor flyweights and playing with springs, etc to get that engine to match that optimum curve. But, that will only optimize it for those specific conditions.
If you want 'timing optimization', go put a fully-computerized EFI on your car. Otherwise, just go for an approximated linear timing line which starts to increase around 800-1000 rpm and maxes out between 2700-3000 rpm at 36 degrees [mechanical only -- for good 'power' performance].
The only way to define an "optimum" timing curve is to put the engine on a GOOD dynomometer and play with it for a few hours...finding the 'optimum' timing for specified conditions at many RPM settings throughout the engine's operating range and at some specified loading on the crank. Then, you can work for many hours whittling on distributor flyweights and playing with springs, etc to get that engine to match that optimum curve. But, that will only optimize it for those specific conditions.
If you want 'timing optimization', go put a fully-computerized EFI on your car. Otherwise, just go for an approximated linear timing line which starts to increase around 800-1000 rpm and maxes out between 2700-3000 rpm at 36 degrees [mechanical only -- for good 'power' performance].
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Optimized for what? Best power? Best economy? At what load?
The only way to define an "optimum" timing curve is to put the engine on a GOOD dynomometer and play with it for a few hours...finding the 'optimum' timing for specified conditions at many RPM settings throughout the engine's operating range and at some specified loading on the crank. Then, you can work for many hours whittling on distributor flyweights and playing with springs, etc to get that engine to match that optimum curve. But, that will only optimize it for those specific conditions.
If you want 'timing optimization', go put a fully-computerized EFI on your car. Otherwise, just go for an approximated linear timing line which starts to increase around 800-1000 rpm and maxes out between 2700-3000 rpm at 36 degrees [mechanical only -- for good 'power' performance].
The only way to define an "optimum" timing curve is to put the engine on a GOOD dynomometer and play with it for a few hours...finding the 'optimum' timing for specified conditions at many RPM settings throughout the engine's operating range and at some specified loading on the crank. Then, you can work for many hours whittling on distributor flyweights and playing with springs, etc to get that engine to match that optimum curve. But, that will only optimize it for those specific conditions.
If you want 'timing optimization', go put a fully-computerized EFI on your car. Otherwise, just go for an approximated linear timing line which starts to increase around 800-1000 rpm and maxes out between 2700-3000 rpm at 36 degrees [mechanical only -- for good 'power' performance].
Thread Starter
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
Paul,
To go with Pete's curve above, scroll down to page 4 of the attached MSD setup instructions to see various "curves.". I put it in quotes because they are pretty linear. Other than the starting point and finishing point, I'm not sure that there is much that you can do to alter the curve itself on a conventional system. I do know that there are programmable versions though I couldn't say how much difference these make.
http://www.jegs.com/InstallationInst...1/121-8516.pdf
To go with Pete's curve above, scroll down to page 4 of the attached MSD setup instructions to see various "curves.". I put it in quotes because they are pretty linear. Other than the starting point and finishing point, I'm not sure that there is much that you can do to alter the curve itself on a conventional system. I do know that there are programmable versions though I couldn't say how much difference these make.
http://www.jegs.com/InstallationInst...1/121-8516.pdf
Optimized for what? Best power? Best economy? At what load?
The only way to define an "optimum" timing curve is to put the engine on a GOOD dynomometer and play with it for a few hours...finding the 'optimum' timing for specified conditions at many RPM settings throughout the engine's operating range and at some specified loading on the crank. Then, you can work for many hours whittling on distributor flyweights and playing with springs, etc to get that engine to match that optimum curve. But, that will only optimize it for those specific conditions.
If you want 'timing optimization', go put a fully-computerized EFI on your car. Otherwise, just go for an approximated linear timing line which starts to increase around 800-1000 rpm and maxes out between 2700-3000 rpm at 36 degrees [mechanical only -- for good 'power' performance].
The only way to define an "optimum" timing curve is to put the engine on a GOOD dynomometer and play with it for a few hours...finding the 'optimum' timing for specified conditions at many RPM settings throughout the engine's operating range and at some specified loading on the crank. Then, you can work for many hours whittling on distributor flyweights and playing with springs, etc to get that engine to match that optimum curve. But, that will only optimize it for those specific conditions.
If you want 'timing optimization', go put a fully-computerized EFI on your car. Otherwise, just go for an approximated linear timing line which starts to increase around 800-1000 rpm and maxes out between 2700-3000 rpm at 36 degrees [mechanical only -- for good 'power' performance].
I have no interest in a full efi setup and dont want to spend hours on a dyno etc. What you said at the end makes sense though. Thats really what my question was about, sorry if I wasnt clear.
From what you and others have said, if I select a set of springs to give me a fairly smooth and linear (ish ) curve, we are good to go but only testing will show.
I'll set all in at 36 and then plot it out and post back the results tomorrow.
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