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"Recurving the distributor"???
- Thread starter karls59tr
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Good morning - here it goes. I'm still learning here as well, so I'd double check the information I provided.
Every distributor has a curve, or mechanism to change the timing, over the range of RPM as the engine is rev'd up and down. The curve will advance the timing, or make it happen at more degrees before top dead center (BTDC). Recurving will adjust the curve to make better use of your engine tune. Some engines like more advance, at an earlier RPM, than others.
Adjusting the curve can sometime have a surprisingly large impact on an engines power.
You might want to contact Jeff at Advanced Distributor. A much of us have used him for distrbutor rebuild. He realy knows his stuff.
https://www.advanceddistributors.com/index.htm
Every distributor has a curve, or mechanism to change the timing, over the range of RPM as the engine is rev'd up and down. The curve will advance the timing, or make it happen at more degrees before top dead center (BTDC). Recurving will adjust the curve to make better use of your engine tune. Some engines like more advance, at an earlier RPM, than others.
Adjusting the curve can sometime have a surprisingly large impact on an engines power.
You might want to contact Jeff at Advanced Distributor. A much of us have used him for distrbutor rebuild. He realy knows his stuff.
https://www.advanceddistributors.com/index.htm
tomshobby
Yoda
Offline
Several of us sent ours to Jeff at Advanced. He does great work.
https://www.advanceddistributors.com/
https://www.advanceddistributors.com/
dklawson
Yoda
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To expand on what's been said above, what it usually means to the owner/driver is paying someone who can make a good educated guess (or someone with a chassis dyno) to replace springs, cams, or bob weights in the distributor so your engine develops the most power it can for its particular configuration.
I made the mistake of asking an acquaintance who knows a lot about such thing if he could recommend what I should do to recurve one of my distributors. Without skipping a beat he snapped back that he wouldn't think of suggesting anything because it would only be a guess and that the only way to properly do this was with the chassis dyno so you could test the results. That said... he went on to be instrumental in developing the 123 Distributor for the A- and B-series BMC engines.
The 123 Distributor has 16 switch selectable electronic advance curves. While my acquaintance did not suggest mechanical tweaks to me, he was capable of mapping out curves good for common engine configurations and program them into his product. His was not a guess but curves mapped for various dyno tested engine configurations.
I made the mistake of asking an acquaintance who knows a lot about such thing if he could recommend what I should do to recurve one of my distributors. Without skipping a beat he snapped back that he wouldn't think of suggesting anything because it would only be a guess and that the only way to properly do this was with the chassis dyno so you could test the results. That said... he went on to be instrumental in developing the 123 Distributor for the A- and B-series BMC engines.
The 123 Distributor has 16 switch selectable electronic advance curves. While my acquaintance did not suggest mechanical tweaks to me, he was capable of mapping out curves good for common engine configurations and program them into his product. His was not a guess but curves mapped for various dyno tested engine configurations.
guzzul
Jedi Warrior
Offline
Adding to what has already been said here about recurving, Jeff at Advanced will also point out that you may want to "re-curve" just to restore the *original* spec to your dizzy.
Over time, the centrifugal weight springs inside your distributor can weaken (even break), and also the plates themselves wear and/or bind. So while you think you are getting x-advance at y-RPM, maybe you're getting more or less. When Advanced rebuilds a distributor, they will check the resulting advance curve against the original spec. to ensure that, in fact, these are working properly. Alternately, they can change springs and/or weights to get different advance characteristics.
There are some neat advantages come to mind regarding the 123 approach that dklawson notes. One of which is the ability to switch to different advance curves for different applications. I could see you wanting to switch to a more performance oriented advance curve on the days you take your TR to the track. And then switching back to something more tame for the street.
Over time, the centrifugal weight springs inside your distributor can weaken (even break), and also the plates themselves wear and/or bind. So while you think you are getting x-advance at y-RPM, maybe you're getting more or less. When Advanced rebuilds a distributor, they will check the resulting advance curve against the original spec. to ensure that, in fact, these are working properly. Alternately, they can change springs and/or weights to get different advance characteristics.
There are some neat advantages come to mind regarding the 123 approach that dklawson notes. One of which is the ability to switch to different advance curves for different applications. I could see you wanting to switch to a more performance oriented advance curve on the days you take your TR to the track. And then switching back to something more tame for the street.
vettedog72
Jedi Knight
Offline
A good wash and polish seems to make my TR6 run much better; but, I wonder how a before and after would compare on the dyno. (Nahh, I know the answer) If perception is good enough then by all means, have the dizzy polished; after all, what is the difference between perception and reality?
On the other hand, if it is frozen or gumed-up, just clean it out. If the springs have weaken, they will just advance the timing a bit early. If it is too early, you will hear it ping.
On the other hand, if it is frozen or gumed-up, just clean it out. If the springs have weaken, they will just advance the timing a bit early. If it is too early, you will hear it ping.