I had an interesting idea using a compass to explain ignition timing. Let me know what you think.
Ignition timing explained
- Thread starter xsellr8
- Start date
The only thing I would add is an explanation as to why, generally speaking, you want the burn to be maximized at 20 degrees after TDC. Maybe using a pedal bike as an example of application of power. Explain that in the same way you can't push the pedal straight down, if the power is made @ TDC or too few degrees ATDC, it has the same result as too soon BTDC. Explain that in general terms, 20 degrees gives the explosion and thus the piston and connecting rod, the best possible leverage to make the best use of the power.
How is important... but without the "why", the "how" doesn't matter.
I was glad to see that you explained how fuel is part of the timing system. So few people get that. I thought it was a good video.
How is important... but without the "why", the "how" doesn't matter.
I was glad to see that you explained how fuel is part of the timing system. So few people get that. I thought it was a good video.
I liked it.
Good to hear. Thank you for watching.
That's good feedback. Thank you for mentioning it. I'll try to explain the "why and how" a bit better next time.
Thank you, glad you liked it.
Not sure I agree with changing the timing vs rpm. While it does sound logical max power is made at a particular timing and most tuners will lock it there for the entire rpm band.
As for the tuner at Shelby. As long as the air/fuel ratio are correct, which is just as important to making max power. Running just under the edge is the "better" tune. This is why most of us get a tune, for more power. This will be obvious when you have 2 cars and one is faster. What you are asking for is a safer tune, which is fine but not what most people want.
As for the tuner at Shelby. As long as the air/fuel ratio are correct, which is just as important to making max power. Running just under the edge is the "better" tune. This is why most of us get a tune, for more power. This will be obvious when you have 2 cars and one is faster. What you are asking for is a safer tune, which is fine but not what most people want.
I have tuned cars ranging from vacuum advanced distributor cars from the 60's all the way up to my last S197. You MUST change the timing as the RPM's change or you are seriously screwing yourself... and may even cause the engine to fail to run due to flooding or breaking parts (depending on what you "lock" timing at).
Fuel burns at a specific rate regardless of the RPM's. The higher the RPM, the earlier you have to start burning the fuel so the fuel burns at the proper time.
Think of it like meeting a friend at the mall. Lets say you and your friend both live 5 miles away from the mall. Lets assume you can both walk 5 mph. If you want to get there at the exact same time, you can leave at the same time Well, if your friend decides to drive his car, and you are stuck walking at 5 mph, the faster he drives, the earlier you need to leave compared to your friend so you both get there at the same time.
Make sense?
I always enjoy your videos. This one is no exception. Well done!
Your video is very confusing, I'm not sure if you don't understand ignition timing or you filmed it wrong. Advanced ignition timing happens BTDC so 20* of timing would be 340* on your compass and not 20* which would be 20* ATDC. Spark happens on the upstroke of the crankshaft because it takes time for the fuel to burn.
The more you advance your timing the closer to TDC the fuel ignites on the ATDC side. Advance timing too much and the fuel will ignite BTDC trying to push the piston backwards.
The more you advance your timing the closer to TDC the fuel ignites on the ATDC side. Advance timing too much and the fuel will ignite BTDC trying to push the piston backwards.
Very good analogy. Thanks for the input
You want the full power of the burn to be happening at 20* ATDC, which means you ignite on the BTDC. ATDC is measured as its own degree after TDC, so even though it looks like 340* that actually means 20* ATDC. It all depends on where your "ZERO*" mark is taken from
Last edited:
Thank you Bob.
Yeah, his strategy is controversal. He ended up getting fired (not sure if that's why). I was talking to several people at a car show who had their car tuned by him and had lost their motor to pre-detonation and that's what got me a bit concerned. They claimed he used too much timing and when I checked mine it was at 22* and the car pegs 9.9 AFR under WOT, so seems he was playing the rich card meets advanced timing strategy.
Last edited:
Users who are viewing this thread
