Timing

[Mattax]

I find it hard to believe they didn’t understand slew rate back then.

You'll have to ask Tuner if he knows when this became fairly well known. The DC literature refers only to possible mechanical causes. So that's why I beleive the guys working there did not know the real reasons. Or maybe better put, they didn't know that it was a major factor. Even today, guys like Tuner and Bill Baldwin, who point this out in the hot rodding community are the exception.

 

[Newbomb Turk]

You'll have to ask Tuner if he knows when this became fairly well known. The DC literature refers only to possible mechanical causes. So that's why I beleive the guys working there did not know the real reasons. Or maybe better put, they didn't know that it was a major factor. Even today, guys like Tuner and Bill Baldwin, who point this out in the hot rodding community are the exception.

I’ll ask him. I know when he figured it out and that’s when he did the ABAB testing on the magnapulse ignition.

It’s better when he tells the stories. The classic one is the timing light fiasco. If I tell it it’s not funny.

When he tells it it’s hysterical.

So whatever year the magnapulse came out was when he figured out the timing was retarding.

When he learned it was from slew rate I’ll have to ask.

I know I learned about slew rate from Baldwin when he called me out for locking out timing on another forum. In fact, he didn’t say slew rate he just said timing retards with rpm.

To say I was stunned would be an understatement. I had to relearn everything, plus find, buy and learn to use a distributor machine.

Slew rate is real.

 

[92b]

Ok, there ONE. And I’d say it’s very rare.

It's not just one. That's just the one I sent you that I had the documentation handy. I not saying that some race engines couldn't benefit from a curve. I'm saying not all will. Some might benefit alot and some very little and most if they will benefit it is after peak horsepower at the very top of the rpm range. This is what my testing has shown me. I'm not the only one either. I talk to other dyno operators who see the same thing.

Plus, I don’t Remember how you tested your curve or how you developed it. I’ve said it before but I’ll say it again.

Trying to develop a timing curve doing sweeps won’t cut it. I know you disagree with that statement but it’s a fact. You might get it close.

Yes, you keep saying that over and over. So far you still haven't explained how. Or shown where this has even been discussed before. You said it was in the superflow manual but that turned out to be about jetting not timing.

I’ve asked you to explain (in relatively simple terms) how an engine wants MORE timing at peak VE and LESS timing at peak power (lower VE) because that is the basis for the argument against a curve.

I provided the dyno sheets but you just dismiss them. I'm not against curves. Some engines/ applications will not see a benefit.

If you just pick a curve based on the same engine family and tune from there you have no idea what MBT timing really is.

I would prefer to use a locked distributor to do this but I can do it with a curve also. I lay the curves over each other. If I know what the timing is and the power at each rpm Increment I can chose the timing amount that produces the most power for each rpm and develop a curve. The same way the engine will experience it. In a natural sweep.

 

[Illahe]

You'll have to ask Tuner if he knows when this became fairly well known. The DC literature refers only to possible mechanical causes. So that's why I beleive the guys working there did not know the real reasons. Or maybe better put, they didn't know that it was a major factor. Even today, guys like Tuner and Bill Baldwin, who point this out in the hot rodding community are the exception.

And some just don't like to share where they found the "last tenth..."

 

[Illahe]

It's not just one. That's just the one I sent you that I had the documentation handy. I not saying that some race engines couldn't benefit from a curve. I'm saying not all will. Some might benefit alot and some very little and most if they will benefit it is after peak horsepower at the very top of the rpm range. This is what my testing has shown me. I'm not the only one either. I talk to other dyno operators who see the same thing.

Yes, you keep saying that over and over. So far you still haven't explained how. Or shown where this has even been discussed before. You said it was in the superflow manual but that turned out to be about jetting not timing.

I provided the dyno sheets but you just dismiss them. I'm not against curves. Some engines/ applications will not see a benefit.

I would prefer to use a locked distributor to do this but I can do it with a curve also. I lay the curves over each other. If I know what the timing is and the power at each rpm Increment I can chose the timing amount that produces the most power for each rpm and develop a curve. The same way the engine will experience it. In a natural sweep.

This makes the most sense to me:

"If I know what the timing is and the power at each rpm Increment I can chose the timing amount that produces the most power for each rpm and develop a curve. The same way the engine will experience it. In a natural sweep."

 

[Newbomb Turk]

It's not just one. That's just the one I sent you that I had the documentation handy. I not saying that some race engines couldn't benefit from a curve. I'm saying not all will. Some might benefit alot and some very little and most if they will benefit it is after peak horsepower at the very top of the rpm range. This is what my testing has shown me. I'm not the only one either. I talk to other dyno operators who see the same thing.

Yes, you keep saying that over and over. So far you still haven't explained how. Or shown where this has even been discussed before. You said it was in the superflow manual but that turned out to be about jetting not timing.

I provided the dyno sheets but you just dismiss them.

I would prefer to use a locked distributor to do this but I can do it with a curve also. I lay the curves over each other. If I know what the timing is and the power at each rpm Increment I can chose the timing amount that produces the most power for each rpm and develop a curve. The same way the engine will experience it. In a natural sweep

Ok, I’ll start from the top.

I’m not surprised you aren’t finding any power on some engines with a curve. And I don’t doubt that the other dyno operators you talk to say the same thing.

I’ll drop a Tuner story here, because he has been dealing with this far longer than I have.

Tuner had an engine on a local builders dyno. I forget but IIRC it was a BBC going in some boat.

And Tuner wanted to do steady state testing to develop a curve for it so he could find out what it wanted and put the curve in the distributor.

The dyno guy said absolutely not for two reasons. One was he didn’t like steady state testing because it’s not what the engine “sees” when running (for the most part that’s true but some places like Daytona they pretty much flat foot it around there) and he wouldn’t let Tuner move the distributor around while the engine was loaded on the dyno.

Tuner told him that if he has to do it in the boat he has to sit right next to the engine and turn the distributor while looking at the vacuum gauge and listening to the engine. He’s still right on top of the engine in the boat.

He got denied. Which is why when Tuner taught me to do it I was doing it the hard way.

I’d get the engine to the rpm I wanted, load it down, run over and grab the distributor and turn it while watching the numbers.

Then I’d grab the timing light and see what the timing was, write it down and move on to the next rpm/load.

Let me tell you the distributor gets pretty hot. Trying to do all that while getting burned by that hot distributor was a giant PITA.

So Tuner said get a big hose clamp and to make a handle and turn it with that. That stopped my hands from getting smoked but it was still a nightmare to do.

So I pulled out an old Mallory 3 step box I had, shipped it down to Nevada for the Dave Telling to look at. He updated it and sent it back to me.

So now, I sit at the desk and move the timing with a knob and watch the vacuum and power numbers.

That’s how you end up with MBT at all rpm you test for.

Now I forgot what the topic was. Ok. That’s how I test for MBT. It takes a butt load of time. Not only funding the curve, but getting the curve on the distributor to match what the engine wants.

My point about the part in the SF book had zero to do with fuel. That’s how SF wrote it up, but it is the same for timing changes and such as well. It takes a number of cycles to see a change. They say 100 cycles (and I read that as 100 sparks per cylinder) just to start to affect timing. Or fuel. My mentors both say it’s 250-300 cycles.

So even IF you are pulling at 600 rpm/sec you’d only see a small change if any in that short time.

So now you know how I do it. Depending on the engine, I pick the lowest rpm the engine SHOULD see WOT and I start at that rpm or maybe a bit lower.

It’s nearly impossible to find MBT doing sweep tests. You can say you can do it, but I’m saying you aren’t at MBT.

I didn’t dismiss your dyno sheets. I could barely read them. That’s not your problem but looking at data or graphs on a screen is hard for me. If I’m looking directly at the screen I don’t mind it. If I’m looking at your graph from your screen through my screen it makes it hard to read.

When I get down to the nut cutting I start printing the graphs and reports. I can take notes on them and things like that.

So I saw them. They were a bit hard to read but I got it. I just disagree that your curve is showing MBT.

I should have mentioned I used a locked out distributor to do steady state testing. If you don’t you are fighting the curve in it to try and develop a curve.

 

[Newbomb Turk]

This makes the most sense to me:

"If I know what the timing is and the power at each rpm Increment I can chose the timing amount that produces the most power for each rpm and develop a curve. The same way the engine will experience it. In a natural sweep."

I wish that were true, but my testing says it’s not so.

I want to start with finding a curve with MBT (MINIMUM timing for Best Torque) and once you do that, the curve is the curve.

Let’s say on my dyno with my timing light an engine wants 20 initial (1000 rpm) and it wants say 26 at peak torque (say 4500ish) and at 6500 it wants 34. That’s the curve. And its SHAPE will always be the SHAPE the engine wants.

What we can’t account for is the way the engine is loaded on the car. It won’t be the same as it is in the dyno. Most of the time anyway.

So what changes? Most of the time you may find it wants 2-4 degrees more initial. And if it does you can give it that much more timing so the whole curve moves up but the SHAPE of the curve is the same.

So now we would have 24 initial, 30 at peak torque and 38 at 6500. The shape of the curve is the same it just took 4 more degrees of timing in the car.

Weather changes timing requirements as far as how much (or little) timing the engine wants in the car too. On a good day with Disneyland weather conditions you may need to pull 4 degrees out so you’d have 16, 22 and 30 but the shape of the curve stays the same.

I hope that makes sense. Finding MBT is where to start. You can’t do that doing sweep testing.

 

[Illahe]

I wish that were true, but my testing says it’s not so.

I want to start with finding a curve with MBT (MINIMUM timing for Best Torque) and once you do that, the curve is the curve.

Let’s say on my dyno with my timing light an engine wants 20 initial (1000 rpm) and it wants say 26 at peak torque (say 4500ish) and at 6500 it wants 34. That’s the curve. And its SHAPE will always be the SHAPE the engine wants.

What we can’t account for is the way the engine is loaded on the car. It won’t be the same as it is in the dyno. Most of the time anyway.

So what changes? Most of the time you may find it wants 2-4 degrees more initial. And if it does you can give it that much more timing so the whole curve moves up but the SHAPE of the curve is the same.

So now we would have 24 initial, 30 at peak torque and 38 at 6500. The shape of the curve is the same it just took 4 more degrees of timing in the car.

Weather changes timing requirements as far as how much (or little) timing the engine wants in the car too. On a good day with Disneyland weather conditions you may need to pull 4 degrees out so you’d have 16, 22 and 30 but the shape of the curve stays the same.

I hope that makes sense. Finding MBT is where to start. You can’t do that doing sweep testing.

Go MSD Grid.

I'm still learning mine, but the more of this thread that I read, the more the products abelites come into play.

 

[Newbomb Turk]

Go MSD Grid.

I'm still learning mine, but the more of this thread that I read, the more the products abelites come into play.

Sadly, you ain’t wrong. Hopefully next week I can get my garbage on the pump.

Then I will see if I can do 12:1 on pump gas AND use vacuum advance.

I know I can do it without VA but I really want to work on part throttle drivability so I want to hammer on it and see what I can do.

If I can’t I may say damn the torpedoes and order a crank trigger and programmable 7 box.

Then I can ride the dots and make my life much easier lol.

But I am now telling guys without an ignition to buy something that can be programmed.

It just makes sense. Or if they want to upgrade I say go programmable. It just makes sense.

 

[Illahe]

Sadly, you ain’t wrong. Hopefully next week I can get my garbage on the pump.

Then I will see if I can do 12:1 on pump gas AND use vacuum advance.

I know I can do it without VA but I really want to work on part throttle drivability so I want to hammer on it and see what I can do.

If I can’t I may say damn the torpedoes and order a crank trigger and programmable 7 box.

Then I can ride the dots and make my life much easier lol.

But I am now telling guys without an ignition to buy something that can be programmed.

It just makes sense. Or if they want to upgrade I say go programmable. It just makes sense.

Being in the poorhouse I bought an MSD (distributor) copy and pulled it down, then welded the advance plate to locked. Phasing became the next hurdle...

 

[92b]

Ok, I’ll start from the top.

I’m not surprised you aren’t finding any power on some engines with a curve. And I don’t doubt that the other dyno operators you talk to say the same thing.

I’ll drop a Tuner story here, because he has been dealing with this far longer than I have.

Tuner had an engine on a local builders dyno. I forget but IIRC it was a BBC going in some boat.

And Tuner wanted to do steady state testing to develop a curve for it so he could find out what it wanted and put the curve in the distributor.

The dyno guy said absolutely not for two reasons. One was he didn’t like steady state testing because it’s not what the engine “sees” when running (for the most part that’s true but some places like Daytona they pretty much flat foot it around there) and he wouldn’t let Tuner move the distributor around while the engine was loaded on the dyno.

Tuner told him that if he has to do it in the boat he has to sit right next to the engine and turn the distributor while looking at the vacuum gauge and listening to the engine. He’s still right on top of the engine in the boat.

He got denied. Which is why when Tuner taught me to do it I was doing it the hard way.

I’d get the engine to the rpm I wanted, load it down, run over and grab the distributor and turn it while watching the numbers.

Then I’d grab the timing light and see what the timing was, write it down and move on to the next rpm/load.

Let me tell you the distributor gets pretty hot. Trying to do all that while getting burned by that hot distributor was a giant PITA.

So Tuner said get a big hose clamp and to make a handle and turn it with that. That stopped my hands from getting smoked but it was still a nightmare to do.

So I pulled out an old Mallory 3 step box I had, shipped it down to Nevada for the Dave Telling to look at. He updated it and sent it back to me.

So now, I sit at the desk and move the timing with a knob and watch the vacuum and power numbers.

That’s how you end up with MBT at all rpm you test for.

Now I forgot what the topic was. Ok. That’s how I test for MBT. It takes a butt load of time. Not only funding the curve, but getting the curve on the distributor to match what the engine wants.

My point about the part in the SF book had zero to do with fuel. That’s how SF wrote it up, but it is the same for timing changes and such as well. It takes a number of cycles to see a change. They say 100 cycles (and I read that as 100 sparks per cylinder) just to start to affect timing. Or fuel. My mentors both say it’s 250-300 cycles.

So even IF you are pulling at 600 rpm/sec you’d only see a small change if any in that short time.

So now you know how I do it. Depending on the engine, I pick the lowest rpm the engine SHOULD see WOT and I start at that rpm or maybe a bit lower.

It’s nearly impossible to find MBT doing sweep tests. You can say you can do it, but I’m saying you aren’t at MBT.

I didn’t dismiss your dyno sheets. I could barely read them. That’s not your problem but looking at data or graphs on a screen is hard for me. If I’m looking directly at the screen I don’t mind it. If I’m looking at your graph from your screen through my screen it makes it hard to read.

When I get down to the nut cutting I start printing the graphs and reports. I can take notes on them and things like that.

So I saw them. They were a bit hard to read but I got it. I just disagree that your curve is showing MBT.

I should have mentioned I used a locked out distributor to do steady state testing. If you don’t you are fighting the curve in it to try and develop a curve.

Thanks for sharing your process. Sorry for sounding like a broken record but If there was a reason why sweep testing doesn't work I missed it.

The part in the superflow book was 100% about fuel and it was good information about how steady state testing a fuel curve can lead to the wrong jetting. It's also why they recommended sweep testing instead.

 

[Newbomb Turk]

Thanks for sharing your process. Sorry for sounding like a broken record but If there was a reason why sweep testing doesn't work I missed it.

The part in the superflow book was 100% about fuel and it was good information about how steady state testing a fuel curve can lead to the wrong jetting. It's also why they recommended sweep testing instead.

I’ll try again.

Doing a sweep test, how do you determine MBT? You can’t because you can’t load the engine, let it stabilize, make a change and see the results.

I’m talking about finding MBT across the rpm range.

How do you do that with a sweep test?

I should have never mentioned the SF stuff. I know what it says.

I also know what my mentors say. That it’s 250-300 cycles (it may be more on some engines) and THEY both say it takes the same number of cycles to affect a timing change.

Never have I said to steady state a fuel test. Ever.

You don’t have the benefit of hearing the conversations I have with the guys who tell me this stuff.

It comes up in normal conversations. One of the guys who mentors me on dyno testing (and I send him dyno data to help me get unstuck when something doesn’t make sense) is very well known in the automotive industry.

If I said his name, many would recognize him. I don’t name drop like that, especially with guys like this one who I know ONLY because of the generosity of Tuner.

Rest assured, if you knew who was teaching me you’d be less likely to dispute what I’m saying.

I mean you have a dyno. You can do some steady state testing and prove Tuner and the other guy wrong.

I can see no reason to not try it.

 

[92b]

I’ll try again.

Doing a sweep test, how do you determine MBT? You can’t because you can’t load the engine, let it stabilize, make a change and see the results.

I’m talking about finding MBT across the rpm range.

How do you do that with a sweep test?

I should have never mentioned the SF stuff. I know what it says.

I also know what my mentors say. That it’s 250-300 cycles (it may be more on some engines) and THEY both say it takes the same number of cycles to affect a timing change.

Never have I said to steady state a fuel test. Ever.

You don’t have the benefit of hearing the conversations I have with the guys who tell me this stuff.

It comes up in normal conversations. One of the guys who mentors me on dyno testing (and I send him dyno data to help me get unstuck when something doesn’t make sense) is very well known in the automotive industry.

If I said his name, many would recognize him. I don’t name drop like that, especially with guys like this one who I know ONLY because of the generosity of Tuner.

Rest assured, if you knew who was teaching me you’d be less likely to dispute what I’m saying.

I mean you have a dyno. You can do some steady state testing and prove Tuner and the other guy wrong.

I can see no reason to not try it.

How will I know your way is better? With a sweep test?

 

[FDNY340]

Sadly, you ain’t wrong. Hopefully next week I can get my garbage on the pump.

Then I will see if I can do 12:1 on pump gas AND use vacuum advance.

I know I can do it without VA but I really want to work on part throttle drivability so I want to hammer on it and see what I can do.

If I can’t I may say damn the torpedoes and order a crank trigger and programmable 7 box.

Then I can ride the dots and make my life much easier lol.

But I am now telling guys without an ignition to buy something that can be programmed.

It just makes sense. Or if they want to upgrade I say go programmable. It just makes sense.

Such as an MSD 6530 or 6520?

 

[Newbomb Turk]

How will I know your way is better? With a sweep test?

Yes.

 

[Newbomb Turk]

Such as an MSD 6530 or 6520?

Yes, either of those two if you want a 6 box. They don’t do as much as the programmable 7 does but most guys on here do not need all the 7 box can do. So the 6 is plenty.