Continuing ignition timing debate from the 416 thread.
Timing requirements are affected by a multitude of factors. I can't tell what factors are in play here. I'm just showing you the result of all those factors.
You can say that my test isn't valid because it isn't a steady state test. But at one point you claimed differences in timing can't be measured on a sweep test on a chassis dyno
Then you built a distributor with a curve and tested it at that same chassis dyno and when it showed a power increase now all of the sudden the numbers are valid. When the dyno operator put a locked distributor in the motor and it lost power on a sweep test you claimed that it validated the fact that your distributor was better. On the same dyno that you said couldn't be used to evaluate Timing curves because it sweeps too fast. I apologize if I seem skeptical but should we believe the results from that dyno or not?
Im not saying your testing isn’t valid. Im saying it’s not complete.
Im also not saying that you can’t change timing and make a sweep test and change the result. Obviously you can. I do it.
What I am saying is you can’t, with a sweep test determine what the engine wants or needs or however you want to say it what a proper timing curve would look like.
Certainly you can add or removing timing (assuming a locked distributor) and see the power change.
Im saying that you have no idea what the engine wants at and around peak torque and peak power if you just sweep it.
In other words, the curve you end up with using a sweep test will be different than a curve you end up with using a steady state load while varying the timing to see where peak torque occurs at that rpm.
The 395 inch example I posted in the other thread is the perfect example of that. There is no way doing a sweep test would end up with 9 crank degrees across about 5500 rpm. The sweep test would want much more timing. Or it may even be very close to locked timing.
That slow, long curve will out power both the quicker, more timing curve or locked out timing.
But the real proof is in driving the car. Ive been sorting out the carb now that it’s in the car and it’s amazing how it drives. Im still working on part throttle stuff but it is clean, smooth and very easy to drive.
And thats with 11:1, pump gas that is 258/263 @.050 with a single plane intake and 1.875 headers. Most people would consider that nasty to drive on the street but it’s not.
If it was mine and it had a stick the engine would have more timing yet but it’s a converter car so I compromised on cam timing a bit. Plus the guy that owns the car wants to be able to drive it with one hand while sipping a coffee with the other and that is very easy driving it.