The craftsman is correct.
Timing
- Thread starter Ironmike
- Start date
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The craftsman is correct.
Hold on. I’m trying to get an engine on the dyno.
I need to look at my notes I took this morning
TT5.9mag
Two atmospheres are better than one
So you’re essentially running on 30 degrees. What story do the plugs tell?
What rpm are you setting timing (35 degrees) at? What is your timing number at 4600 rpm?
You need some help with that? You're gettin purdy old, you know.
lol I got it on there. Tomorrow I start making pulls on that one. It will only be a few pulls as it’s been across the pump before. This is just a little check out before it goes to the customer.
Lets do the unicorn head motor before I put it in.
Pretend your timing light is a pistol. With the engine spinning slowly you take two shots in rapid succession when you see the 36 degree before top dead center mark line up with the pointer on the cover. Because you are an excellent marksman the first bullet hits the 36 degree Mark. The second bullet fired (representing the slower timing light) will hit a number that is smaller before top dead center.
Mattax
Just the facts, ma'am
Timing lights are effected by the time it takes for the electronics to switch, just like the electrontronic ignition boxes. The discussion here started because of a timing light. More circuitry and more time required to be expected in a 'dial back'.
Mallory Unilite timing issue
Playing with a big block, chasing an off idle stumble. While checking the distributor, I noticed that the timing would retard as much as 8 degrees when I snapped the throttle. Made sure that the vacuum advance was disconnected to prevent false readings. Still the same result. Timing isn't ...
board.moparts.org
A multi-strike can cause issues too. I don't really know how that's resolved. It's been discussed but it seems like sometimes its a problem and sometimes its not.
Mattax
Just the facts, ma'am
Larry is around. Might be able ask him. (He responded to some of my emails about Dynomation 5 and the skewed power curve with Chrysler cams. Figured out here with Jim's help that the cam info had made incorrect assumptions about the .006 durations)
I beleive the reason for the fast advance to a 'limit' was an inheritance from success in class racing doing this with dual point distributors. Circle back to that at the bottom.
Probably. The copy editing and checking only got worse with later editions.
That looks to be the same graph the was further simplified in later editions.
This is from my copy of Engine, Speed Secrets
When waiting for my tach drive distributor, John Soemer - a former Stock class racer related the story of removing the heavy spring and going slower. I think he said that at the tech seminars they were telling racers not to do it, and son of a gun the factory guys were right.
In the thread linked below I posted the above graph with my measurements on a Excel graph.
See if this helps. This a the advance curve of a SB tach drive distributor I ran on a machine. The blue line is from the mopar book pictured earlier in the thread.
Timing is in distributor degrees and rpm.
Marked up on the graph is a circle and timing in crank degrees and rpm. The circle represents the timing on an engine when the distributor is set to 35* at 2000 rpm.
Timing is in distributor degrees and rpm.
Marked up on the graph is a circle and timing in crank degrees and rpm. The circle represents the timing on an engine when the distributor is set to 35* at 2000 rpm.
I believe the research that A&W Performance did on ignition curves can be used to program the MSD grid system.Larry is around. Might be able ask him. (He responded to some of my emails about Dynomation 5 and the skewed power curve with Chrysler cams. Figured out here with Jim's help that the cam info had made incorrect assumptions about the .006 durations)
I beleive the reason for the fast advance to a 'limit' was an inheritance from success in class racing doing this with dual point distributors. Circle back to that at the bottom.
Probably. The copy editing and checking only got worse with later editions.
That looks to be the same graph the was further simplified in later editions.
This is from my copy of Engine, Speed Secrets View attachment 1716481055
View attachment 1716481054
When waiting for my tach drive distributor, John Soemer - a former Stock class racer related the story of removing the heavy spring and going slower. I think he said that at the tech seminars they were telling racers not to do it, and son of a gun the factory guys were right.
In the thread linked below I posted the above graph with my measurements on a Excel graph.
See if this helps. This a the advance curve of a SB tach drive distributor I ran on a machine. The blue line is from the mopar book pictured earlier in the thread.
Timing is in distributor degrees and rpm.
Marked up on the graph is a circle and timing in crank degrees and rpm. The circle represents the timing on an engine when the distributor is set to 35* at 2000 rpm.
I was talking to Warren about working with Larry and Bob six months ago. His recollections of their engine set ups differ slightly from some published data. We spoke about Bob, and he said that he should reach out to him. Is Bob still around?
When I asked him about keeping an LA short block together at high RPM (over 7500) and A&W's (Published) crossover oiling modifications that get so much hype, he said, " I don't recall ever running them." He added that he trapped their 340 effort in the 9k range and kissed a piston with a valve on occasion while crossing the stripe. If my recollection is correct, he said they were running six series gears.
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On the DC graph you posted it looks like about 3 crankshaft degrees of advance over about 7000 engine rpm. Less than 1/2 degree per 1000 rpm. The footnote list only list mechanical reasons for the advance compensation. No mention of slew rates or modules. Is this for a dual point distributor?Larry is around. Might be able ask him. (He responded to some of my emails about Dynomation 5 and the skewed power curve with Chrysler cams. Figured out here with Jim's help that the cam info had made incorrect assumptions about the .006 durations)
I beleive the reason for the fast advance to a 'limit' was an inheritance from success in class racing doing this with dual point distributors. Circle back to that at the bottom.
Probably. The copy editing and checking only got worse with later editions.
That looks to be the same graph the was further simplified in later editions.
This is from my copy of Engine, Speed Secrets View attachment 1716481055
View attachment 1716481054
When waiting for my tach drive distributor, John Soemer - a former Stock class racer related the story of removing the heavy spring and going slower. I think he said that at the tech seminars they were telling racers not to do it, and son of a gun the factory guys were right.
In the thread linked below I posted the above graph with my measurements on a Excel graph.
See if this helps. This a the advance curve of a SB tach drive distributor I ran on a machine. The blue line is from the mopar book pictured earlier in the thread.
Timing is in distributor degrees and rpm.
Marked up on the graph is a circle and timing in crank degrees and rpm. The circle represents the timing on an engine when the distributor is set to 35* at 2000 rpm.
It looks like what they were trying to achieve by adding 3 degrees of advance over 7000 rpm on a distributor machine was to end up with a curve that remained flat as measured in a running engine? That is interesting because it doesn't compensate by adding or subtracting timing for changes in VE in the curve. Either in this case it didn't need it or they didn't test to see if it did need it. My suspicion is that a deviation from a flat curve (as observerd on the running engine) will be combination / application specific. As will the amount of horsepower gained or lost from a deviation of the flat curve be combination/ application specific. For now I'm going to assume these test were not done with electronic ignition but the same theory probably applies. You just have to compensate for the additional timing loss if there is any. Using a distributor machine to measure a timing curve with points is pretty straight forward but maybe not so much with electronic ignition. The strobe in a distributor machine when using a points distributor is triggered by the mechanical grounding of the points. I suspect the low voltage AC output of a pickup coil is not going to directly power the strobe in the distributor machine. I suspect it needs some circuitry to convert that ac signal to a ground which introduces a slew rate for the distributor machine. This is why I feel when testing on the distributor machine with electronic ignition it is best to use the entire ignition system and use a timing light for the strobe sourced from the secondary ignition being tested. The distributor machine is basically just spinning the distributor.Larry is around. Might be able ask him. (He responded to some of my emails about Dynomation 5 and the skewed power curve with Chrysler cams. Figured out here with Jim's help that the cam info had made incorrect assumptions about the .006 durations)
I beleive the reason for the fast advance to a 'limit' was an inheritance from success in class racing doing this with dual point distributors. Circle back to that at the bottom.
Probably. The copy editing and checking only got worse with later editions.
That looks to be the same graph the was further simplified in later editions.
This is from my copy of Engine, Speed Secrets View attachment 1716481055
View attachment 1716481054
When waiting for my tach drive distributor, John Soemer - a former Stock class racer related the story of removing the heavy spring and going slower. I think he said that at the tech seminars they were telling racers not to do it, and son of a gun the factory guys were right.
In the thread linked below I posted the above graph with my measurements on a Excel graph.
See if this helps. This a the advance curve of a SB tach drive distributor I ran on a machine. The blue line is from the mopar book pictured earlier in the thread.
Timing is in distributor degrees and rpm.
Marked up on the graph is a circle and timing in crank degrees and rpm. The circle represents the timing on an engine when the distributor is set to 35* at 2000 rpm.
Mattax
Just the facts, ma'am
As far as I have ever known those are supposed to be for the magnetic impulse race distributors. By the time this version was published dual points were no longer available from DC. I beleive the P parts listed there may have been the spring kits or the conversion packages. Those p/n are no longer listed in my 1989 catalog and I can't find the matching price list which sometimes included older parts no longer shown in the glossy catalog. The distributor advance I measured was on a race distributor bought around 1989.
I never heard of slew rate until 'Tuner' brought it up, but that is the real reason.* The explanation in the book may also factor in. Or, its someone's hypothesis presented as a fact. There's plenty of reason to suspect that the person who put together these later editions didn't really know much about the R&D. (he may have thought he did). @Illahe may be able to show us more from the earlier edition, which was clearly written by, or at least alongside, the guys who were doing the dyno testing. Even there, its not clear what they (or their sponsered teams) found at the track. When that was written they were probably still learning.
*We know its the real reason because we've heard it from the horses mouth's that they lost e.t. and mph going from dual point to electronic with the exact same advance set up. It wasn't just my co-worker. And it wan't just Tuner. As Tuner pointed out in his post, this stuff was in Jenkin's book on the small block Chevy. All of the guys running 'heads up' if you will were running into this.
Mattax
Just the facts, ma'am
When this was done they were still transitioning from dual point to electronic. As I describe in the linked thread, clearly their focus was on the fastest classes in drag racing. The base line was what had worked well with dual points. Key things for them seem to have been; 'best' timing for the power band, and easy hot starting. Right or wrong, they didn't see idle as important or developing a curve as a good use of their resources.
We know Petty went off and did a bunch of development largely on his own when he was going with Chrysler. We all know what happened with Chrysler's support for sports car racing - and that was also right in the same era when transistorized ignitions were being adopted. This uneven support for racing meant a lot of catch up and also meant institutional knowledge got lost. Sorry for the rant - but this impacted the published info especially by the 1980s and 90s.
Mattax
Just the facts, ma'am
Another thought. The reason given for the mechanical loss of timing are clearances in the timing chain, intermediate gear, etc.. What are the chances that this would be the same for each motor? Also is it possible that it may not be linear with rpm for every motor? If there is variation, what would be the scale of that variation?Larry is around. Might be able ask him. (He responded to some of my emails about Dynomation 5 and the skewed power curve with Chrysler cams. Figured out here with Jim's help that the cam info had made incorrect assumptions about the .006 durations)
I beleive the reason for the fast advance to a 'limit' was an inheritance from success in class racing doing this with dual point distributors. Circle back to that at the bottom.
Probably. The copy editing and checking only got worse with later editions.
That looks to be the same graph the was further simplified in later editions.
This is from my copy of Engine, Speed Secrets View attachment 1716481055
View attachment 1716481054
When waiting for my tach drive distributor, John Soemer - a former Stock class racer related the story of removing the heavy spring and going slower. I think he said that at the tech seminars they were telling racers not to do it, and son of a gun the factory guys were right.
In the thread linked below I posted the above graph with my measurements on a Excel graph.
See if this helps. This a the advance curve of a SB tach drive distributor I ran on a machine. The blue line is from the mopar book pictured earlier in the thread.
Timing is in distributor degrees and rpm.
Marked up on the graph is a circle and timing in crank degrees and rpm. The circle represents the timing on an engine when the distributor is set to 35* at 2000 rpm.
Still reading through all of this. The quote below from tuner is what I suspected. It gives the purpose of the curve ( as measured on the distributor machine ) and hints that not all motors will want to be a flat curve (as measured on the running engine).
Tuner:
"The mechanical advance compensates for the retard in the electronics to provide a flat static total or continue to advance all the way through the RPM range, however the engine likes it and you set it up."
@Mattax
I should have made a seperate post on this What are your feelings about the possibility of introducing an aditional slew rate when converting the ac signal from an electronic distributor to a grounding signal for the strobe on a distributor machine?
I should have made a seperate post on this What are your feelings about the possibility of introducing an aditional slew rate when converting the ac signal from an electronic distributor to a grounding signal for the strobe on a distributor machine?
Im pretty sure that’s not what he means.
He is saying you need to address the retard with the curve. Even a points distributor, which doesnt retard wants a curve.
I know you are hung up on testing this on a distributor machine but I’m not sure why. You can CLEARLY test for retard on a test bench and do it far more accurately than trying to do it in a car.
And doing it in the car means doing it with a timing light, which adds in error. I know what the retard is on my machine like the ignition will run in the car. Any variation of that is from the timing light.
Jenkins and his nylon cam gear...
"The reason given for the mechanical loss of timing are clearances in the timing chain, intermediate gear, etc." Quoting 92b
Would the scale of timing variation on a mechanically driven distributor be proportionally effected by the loading (and unloading) of the crank to cam and cam to distributor drive/oil pump.
Perhaps, the load slightly decreases as the efficiency of the drive mechanism increases, and thus the slight vernation, (dog leg) is needed to compensate as in A&W's published data.
I don't think I'm misinterpreting what he wrote but what you're saying is he didn't write what he intended to write?
Right. I believe that testing was done with points so the only loss of timing issues would be mechanical issues like junk timing chains and such. Or point bounce.
When you add electronics in you add in slew rate and that changes everything.
I believe that is one reason why two identical ignition systems can produce different power. One box retards sooner (or later as may be the case) and/or it retards more. My testing has shown repeatedly none of these boxes retard the same. Not in amount or in the rpm when it starts retarding.
Im not saying that at all. Im saying I know what he says and he’s never said a statement like that to me to mean anything other than what I posted.
And I get it straight from him. I could be wrong but I’ll ask him the next time I talk to him to clarify it.
I agree wholeheartedly. We're in the century of crank triggers and data recorders, but some of us are budget constrained, so the old R&D comes into play.
The SS racers had "cut down" oil pumps and very thin oil. Considering A&W's relationship with K.B.'s Bob Tozzi and his oil pump research (Dyno) it seems logical to hypothesize that the oil pump loading and unloading may have effected the timing curve as well.
My understating of Jenkins preference for the nylon cam gear was an intentional cam timing variation when the car cam off load at the top end. Watching him on film you'll notice a slight pull sometimes near the the first timing light on the big end...
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