More power!

While I was sorting out my problems with the Pertronix system one of the times I got the car running it seemed to have more power. On the presumption that the source was a slight chance in timing caused by the "points" sensor install, I moved the distributor a bit before the event today to increase the advance and yes I got noticeable more power. Ya! After starting the car 8-10 times, mostly with the backup starter battery, the car would not turn over. My co driver Steve, who is a mechanic with many years experience, said we were getting too much compression from the too advanced timing to allow the slightly used batteries to turnover the engine. This eve I backed the timing off a bit and on nearly the same charged batteries, the car turned over and started up.
I want the extra power back! Anyone have an idea of how to deal with getting the car to turn over to get it started with the added advance?
I am going to play with it more at tomorrows event.
Video from today will be posted tomorrow. I almost got beaten by an amazing driver and Porsche 912 combo. He was probably faster than the GT2 I frequently compete against(for TTOD).
Mark

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Originally Posted by mwizard

While I was sorting out my problems with the Pertronix system one of the times I got the car running it seemed to have more power. On the presumption that the source was a slight chance in timing caused by the "points" sensor install, I moved the distributor a bit before the event today to increase the advance and yes I got noticeable more power. Ya! After starting the car 8-10 times, mostly with the backup starter battery, the car would not turn over. My co driver Steve, who is a mechanic with many years experience, said we were getting too much compression from the too advanced timing to allow the slightly used batteries to turnover the engine. This eve I backed the timing off a bit and on nearly the same charged batteries, the car turned over and started up.
I want the extra power back! Anyone have an idea of how to deal with getting the car to turn over to get it started with the added advance?
I am going to play with it more at tomorrows event.
Video from today will be posted tomorrow. I almost got beaten by an amazing driver and Porsche 912 combo. He was probably faster than the GT2 I frequently compete against(for TTOD).
Mark

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Not addressing your specific needs regarding power and timing...just to answer your question Your timing needs to be "retarded/less advanced" static for it to be easier to crank. Then ignition advance come in with RPMS so that you have the timing you want at rpms.

Ok , video up ahead of schedule.
https://youtu.be/Xqt_bTRRwPk
Mark

Hi Mark,
You may remember me from Marina. I have the open wheel BM mod car and haven't run in a while.

You can't run as much advance at cranking speeds obviously, but then you want to have it come in quickly to help your low end power on the course. By backing off (turning the distributer) you can start with low cranking advance. You can use a light tension spring (or heavy weights) to allow the advance to come in quickly above cranking RPMs.

After that, it gets a little more complicated.

The advance increases with RPM due to the flyweight shape and its effective force from its weight ( ramp curvature) overcoming spring tension. As an example, you can use a spring so light that all the advance is in just over idle.

The next trick is not to over-advance the engine at high load and/or high RPM where the cam timing effectively increases compression. You can lose power and possibly not even feel it nor hear any detonation because of exhaust noise. Limiting the total advance is one way to help prevent too much advance at high RPM on the cam's power peak.

Dyno tuning an exacting way to do this where the optimum timing at different loads and RPMS can derived by turning a "locked advance curve" distributor while the car is on the dyno. Then one uses a distributor machine to spin the unlocked advance curve distributor and watch the advance change vs. RPM. You change weights and springs and overall advance limit pins to make it look like you want.

Years ago (when cars were a lot slower and you had time to do things like this), drag racers were fond of having a dashboard switch to switch in another set of points that were offset from the other set to retard the motor in its top gear near the end of the qtr. mile. That allowed more HP to be developed under high load from air drag and helped trap speed.
The car would also crank over easier on the retarded point set.

-Chuck

Thanks, Chuck. Jesus said something similar with less detail today at the event. I have a Pertronix distributor. I will be contacting them tomorrow about getting more info on their dist. so I can figurer out what might be possible.
So, how come have you not been coming out?
Mark

Haven't been out for a while because of intensive period of slave labor on our house, and before that, some health issues.

Sold our house last month and now tidying up the garage at the house where we rent to get the car in and work on it. Not a lot to do on it. I really really miss those G-forces!