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I just replaced my original dist with a 123. I used the 1750 curve they have and the car is running much better now (old dist had a lot of play). But The car feels a little flat. The RPMs don't build as quickly as before. The timing is right on and the max advance at 4500 RPM looks right.

I haven't touched anything else but just thought I would make sure I was using the right curve before looking elsewhere.

I have been thru the SPICA routine about 3 times now and start up is clean, am not getting any smoke and plugs are staying clean and not too lean.

I would appreciate any thoughts!
 

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Curve #1 works well with Webers on a 2L motor and I expect that it would work well for you. It gives 32 degrees of advance at 4200 rpm, so 8 degrees static will give you 40 degrees max, etc.
 

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Beware of the static timing instructions. They imply that you set the LED to just come on at TDC. It must come on at whatever the static timing is. I measured the diameter of the pulley, calculated the circumference - pi*D, then measured the distance from TDC to the static timing mark as Circumference * d/360 where d is the number of degrees of static advance. Is that sufficiently confusing?
 

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my experience with curve 1 is that when idling the timing is very unstable; timing marks moving up and down. The modified 006 curve has better idling behavior. Has anyone seen this as well?
 

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my experience with curve 1 is that when idling the timing is very unstable; timing marks moving up and down. The modified 006 curve has better idling behavior. Has anyone seen this as well?
Definitely not. I experienced difficult idling with the Shankle curve. The...045 behaved perfectly. The ...006 gives poor throttle response and poor gas mileage in my car. The "006 tuning" - (the Jim Kartamalakis curve) works best for me now with RJ racing cams and cylinder head.
 

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Ed,

How much static advance did you use for the 45 curve? 8 degrees? And how did you measure this, by the led and the engine turned off, of with an ignition timing lamp while idling?

Agree on the 006, if static advance is limited (3-4 degrees). When increasing idle advance to 10-12 degrees, then engine response improves, however, the max advance becomes too large.

006 tuning seems indeed best, with idle advance of 12 degrees. Higher idle advance improves the response of the engine, but the starter seems to have difficulties when trying to crank the engine. This seems to indicate that
- when cranking the engine the advance should be low ( < 10)
- when idling the advance should be higher (say 14-15)
In fact this behaviour is in the 45 curve, but when increasing idling advance to 14-15, then the max advance becomes too high.

I did not encounter the bad idling behavoir for the shankle curve. However, if I recall one of your threads, the issue was that the revs went up, making it for the engine difficult to idle at low rpm (around 900).

The idling instability I mention for the 45 curve is that when iding the timing mark seems to be moving randomly when using a ignition timing light. I do not understand why this happens. With a breaker marelli distributor, and with a breakerless bosch distributor the idle advance is very stable. Hence it must be related to the 123 distributor.

By the way, are you using teh 123 with vacuum advance or without?
 

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The idling instability I mention for the 45 curve is that when iding the timing mark seems to be moving randomly when using a ignition timing light. I do not understand why this happens.
I misunderstood your earlier post. I don't know if I experienced this.

I ran the ..045 curve with various degrees of advance. I had 40 degrees max at one point. I think that I settled on 36-38 before I tried another curve.

I have the JK curve at 15 degrees static = about 36 max.
 
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