good overview of split timing, i would like to add to it. the reason for changing split timing is the rate at which fuel burns, more pressure causes the fuel to burn faster (flame propagation). this is why you want to retard timing and increase split with pressure. we can use manifold pressure as an estimation of CCP but it is not obvious that is actually the case and what we will likely find is that CCP, which affects combustion rate, is highest somewhere around peak torque rpm for a given MAP. too much split will cause an incomplete burn, much like disabling the trailing plugs. too little split may result in a knock situation, think about it like trying to punch something to get it to move instead of pushing on it. at lower CCP the uncontrolled burn may just result in a loss of power that pulling the trailing plugs makes better, at higher CCP the uncontrolled burn may have enough force to damage the engine.
Hey brian how are u?? Can u help with a basic injector angle map the total safe degrees i can run on a full bridge semi pp 13b.. please cant find anything that makes sence
I have read somewhere that mazda built race engines have zero leading/trailing split. Does it follow that less split means less chances of detonation? If this is true, I would be inclined to just deactivate my trailing coils and sacrifice a few ponies just to be safe from detonation.
world market FC turbo ( N318 ) has same plug positions as FD . the usa is not centre of universe. you get N332 instead and it has the same freaky spark locations as MFR and s4 NA ( N 326 ) . the VAST majority of FC turbo engines in the workd have same plug position as FD
Q...for a stock or mild street port...what is a good base L1 timing advance number? I see many charts show 0 degrees up to 6 deg BTDC What confuses me is I also see many youtubers running numbers as wild as 15 BTDC initial advance for a stock motor. Isn't this too agressive inital advance? Q2....with Approx 12 Deg Split....I have tried timing of -5 Retarded deg L1...0 Deg L1 and 5 Deg Advance BTDC inital timing at idle.....I Did not notice much difference throughout the rpm range but it seemed smoother with less decel pop at 5 Deg initial L1 advance.....This leads me to believe the engine may like more advance. Wondering how much advance can I go before engine knocking occurs and will I even notice when Knocking starts to occur before engine damage has happened? Specs Pre'86 13B, RB 4 barrel Intake, Tuned Edelbrock 600 CFM Carb, 2.5 Inch header open exhaust with resonator Thanks in advance.
For your particular setup, Racing Beat has most of these questions answered for you. Generally all of my tuning is a full standalone aftermarket ECU with full engine control of all fuel and spark variables. That's why I'm unable to answer your question as you intended. Timing is shaped, not an on/off switch or singular value.
@@RGHTBrainDesignDrive Ok thank you. I have looked at Racing Beats info before but it is pretty basic. Just trying to gain as much of others experience as I can since there is not much out there for carb tuning with timing split, using different spark plugs etc But actually I think I got it now....I discovered there is a ball bearing in the dizzy that allows the stator plate to rotate under vacuum to pull in advance. Found it was gummed up and not rotating and needed lubed.
That was the best I've ever heard it explained.
good overview of split timing, i would like to add to it.
the reason for changing split timing is the rate at which fuel burns, more pressure causes the fuel to burn faster (flame propagation). this is why you want to retard timing and increase split with pressure. we can use manifold pressure as an estimation of CCP but it is not obvious that is actually the case and what we will likely find is that CCP, which affects combustion rate, is highest somewhere around peak torque rpm for a given MAP.
too much split will cause an incomplete burn, much like disabling the trailing plugs. too little split may result in a knock situation, think about it like trying to punch something to get it to move instead of pushing on it. at lower CCP the uncontrolled burn may just result in a loss of power that pulling the trailing plugs makes better, at higher CCP the uncontrolled burn may have enough force to damage the engine.
Hey brian how are u?? Can u help with a basic injector angle map the total safe degrees i can run on a full bridge semi pp 13b.. please cant find anything that makes sence
Great stuff
Good info. Head still. Big boy
I have read somewhere that mazda built race engines have zero leading/trailing split. Does it follow that less split means less chances of detonation? If this is true, I would be inclined to just deactivate my trailing coils and sacrifice a few ponies just to be safe from detonation.
No, you have it backwards. More split = Safer.
world market FC turbo ( N318 ) has same plug positions as FD . the usa is not centre of universe. you get N332 instead and it has the same freaky spark locations as MFR and s4 NA ( N 326 ) . the VAST majority of FC turbo engines in the workd have same plug position as FD
Thank you for the clarification, Sir.
Q...for a stock or mild street port...what is a good base L1 timing advance number?
I see many charts show 0 degrees up to 6 deg BTDC
What confuses me is I also see many youtubers running numbers as wild as 15 BTDC initial advance for a stock motor.
Isn't this too agressive inital advance?
Q2....with Approx 12 Deg Split....I have tried timing of -5 Retarded deg L1...0 Deg L1 and 5 Deg Advance BTDC inital timing at idle.....I Did not notice much difference throughout the rpm range but it seemed smoother with less decel pop at 5 Deg initial L1 advance.....This leads me to believe the engine may like more advance.
Wondering how much advance can I go before engine knocking occurs and will I even notice when Knocking starts to occur before engine damage has happened?
Specs Pre'86 13B, RB 4 barrel Intake, Tuned Edelbrock 600 CFM Carb, 2.5 Inch header open exhaust with resonator
Thanks in advance.
For your particular setup, Racing Beat has most of these questions answered for you.
Generally all of my tuning is a full standalone aftermarket ECU with full engine control of all fuel and spark variables. That's why I'm unable to answer your question as you intended. Timing is shaped, not an on/off switch or singular value.
@@RGHTBrainDesignDrive Ok thank you. I have looked at Racing Beats info before but it is pretty basic. Just trying to gain as much of others experience as I can since there is not much out there for carb tuning with timing split, using different spark plugs etc
But actually I think I got it now....I discovered there is a ball bearing in the dizzy that allows the stator plate to rotate under vacuum to pull in advance. Found it was gummed up and not rotating and needed lubed.