What a meager difference to call someone out on, but ok.
MP Dizzy?
- Thread starter Cuda416
- Start date
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What a meager difference to call someone out on, but ok.
I was just setting it straight. It is not a race dist as u referred to in the post u deleted. Kim
I haven't deleted a post. But thanks for settin me straight.
Ok, sorry I didn’t see where u said it was more of a race dist than not so good for the street. Kim
Cuda416
Well-Known Member
Quick question on total advance.
When say, 15 initial, 20 mech and 15 vacuum, come together (if they ever do) it adds up to more than half of the distance between towers, with 25 deg in the distributor. What keeps the previous tower from pulling the spark?
When say, 15 initial, 20 mech and 15 vacuum, come together (if they ever do) it adds up to more than half of the distance between towers, with 25 deg in the distributor. What keeps the previous tower from pulling the spark?
mopowers
Well-Known Member
Does it have anything to do with the fact that the distributor rotates half as quickly as the crank? Crank degrees are different that distributor degrees.
Cuda416
Well-Known Member
I believe so, part of what I'm trying to confirm. That's also why I said 25 degrees into distributor when there's 50 total at the crank. I'm still trying to learn so, so I could be way off on a lot of things regarding this stuff.
mopowers
Well-Known Member
I misunderstood your question. I'm sure others can explain it better than me, but I believe you're thinking about it incorrectly. When you advance the ignition timing, it still sends a spark when the rotor hits the appropriate contact on the cap - it just happens sooner in a particular piston's stroke.
Cuda416
Well-Known Member
The source of my question comes from a discussion about reluctor/rotor phasing and watching the MSD and other videos that show the effects of phasing and at the same time, the effects of what appear to be advance. As the RPM changes, the relationship between the rotor and the cap contact changes throughout the curve.
I'm not saying you're wrong about me being wrong, hell, that's why I'm asking the question lol. This is one of those things that probably won't matter much in the long run but I'd like to fully understand it just in case. Hard to diagnose or tune a system when you don't know what all the knobs can do.
So, to be clear, my question is just about clarifying my assumption on the idea that with a properly phased rotor, meaning it's sweet spot puts it no further from the contact either fore or aft of the contact, is it simply not possible to fire off of another tower given the numbers previously stated?
Okay, scratch what I just wrote. I left it in place for posterity..
As I wrote that, the gears were turning and I think I have it. Thanks for the gentle nudge.
My understanding now is thus....
mech adv kicks in, and the weights swing out, which changes the relationship between the crank angle and the rotor. The relationship between the reluctor and the pickup doesn't change and neither does the relationship between the rotor and cap. So, as you say, the spark will fire when the spark fires....
This leads me to vacuum advance and the fact that it does change the reluctor/pickup relationship, but not the relationship between cap/rotor. So again, spark happens earlier/later with respect to the crank angle.
Now, I think the last part of this puzzle for me is the phasing video. It's the change in relationship in cap/rotor when spark simply due to the speed of the pass between them? Simply put, the rotor is spinning faster but the spark is still moving a the same speed down the wire and actually "jumps" slightly later in the pass?
Thanks again, bear with me, I'll catch up. lol
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