Rat Bastid
Dunamis Metron
Yeah, a scooter, hole in my head and a new wife.
Before I hit 62 (a little over 2 years from now) I‘m going to buy a Speed Triple Triumph to blast around on. A scooter would kill me.
figuring out advance timing
- Thread starter Backally
- Start date
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Yeah, a scooter, hole in my head and a new wife.
Before I hit 62 (a little over 2 years from now) I‘m going to buy a Speed Triple Triumph to blast around on. A scooter would kill me.
Ken took the website down.
Apparently he gave up or sold the domain name.
Lots of good stuff lost.
I may have saved the first page intact with full html.
I need to figure out some ways to post it.
Here we go. It was saved at the Wayback machine.
Thanks, I’m going to be diving into all this stuff soon
TT5.9mag
Two atmospheres are better than one
@champyfz450
I can’t really add much to what @Mattax posted, he’s spot on. Quantifying your results will be the most difficult part of cruise tuning, and what you’re looking at will be mpg and “feel” which both aren't very quantifiable. Don’t worry too much about what your table looks like when you begin tuning. You can go back after the fact and smooth or interpolate the table and make it look better in the 3d model. Sharp spikes or dips are generally not what you’re after. I will say datalogging and overlaying the log on to the base map is the easiest way for me to see what is happening “right now” rather than tuning live. Don’t forget to go back and look at fueling after making timing changes in certain ranges, as both will affect each other.
I can’t really add much to what @Mattax posted, he’s spot on. Quantifying your results will be the most difficult part of cruise tuning, and what you’re looking at will be mpg and “feel” which both aren't very quantifiable. Don’t worry too much about what your table looks like when you begin tuning. You can go back after the fact and smooth or interpolate the table and make it look better in the 3d model. Sharp spikes or dips are generally not what you’re after. I will say datalogging and overlaying the log on to the base map is the easiest way for me to see what is happening “right now” rather than tuning live. Don’t forget to go back and look at fueling after making timing changes in certain ranges, as both will affect each other.
Thanks. I figured you know EFI and 360s.
@champyfz450
I'd say for steady cruising, inch toward the limits I mentioned above. Too lean at steady load (interstate cruise) the engine will surge and too much timing you will hear (and can also be seen on the spark plugs). Back off as much as two or three degrees from too much timing advance at cruise. This will help account for when the engine really gets heat soaked on a longer trip.
Starting and Idle:
I see no reason to have that much timing when starting. It ran with less than 10 , so 12* should be fine for cranking speeds (under 500 rpm).
Over 20 is just going to be hard on the starter.
At idle rpms, 600-900, that cam shouldn't need 22* unless running it lean, or compression is low.
If its an automatic transmission, test the same as with a carb & distributor.
As it is now, put it gear and see what rpm it drops to. Write down the rpm in neutral and in gear. If available, note the MAP in gear.
Then take 2* out of timing. Put it in gear and see if there is less drop in rpm. Less drop demonstrates more power.
Do the same removing 2* more so its at 18*.
For both 20 and 18* experiment with a little richer mix than current.
Try going richer first in a couple of increments. If not seeing any more power, then go leaner. Go leaner in small steps as power will drop off more quickly going leaner. If you've set idle mix on a carb, you've probably experienced that.
When power drops off (as demonstrated by lower rpm and vacuum (higher MAP)) note that, and make it a bit richer.
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Rat Bastid
Dunamis Metron
Great advice
TT5.9mag
Two atmospheres are better than one
With EFI you can get kind of crazy with timing because you’re not limited to the 2D curve from springs and weights. And on the holley there’s a bunch of timing table multipliers. Like start retard. Let the engine tell you what it wants. If it idles best at 12 degrees use that. If it idles best at 30 use that. Then use the cranking ign table modifier to yank timing for starting. The critical values are still the same though, wot and peak torque. That’s where some caution needs to be taken. The cells around peak tq are where you most likely hurt the engine if you get too crazy with it. Be conservative there.
Old thread, but there's a very simple solution. As I try to preach on damn near a daily basis sometimes, ALL THIS is covered in depth in the Master Mopar Performance engine manual. It describes in DEPTH how to use a vacuum gauge to find highest cruise vacuum in conjunction with a timing light and get the timing curve SPOT ON. But no matter how much I preach it, it either falls on deaf ears, or somebody shoots it down with an stupid argument. Normally the arguments are that the MP manual is dated. That's pretty stupid considering distributors, carburetors and vacuum devices are also dated. Kinda matches up, don't it? You can get a perfect timing curve in a weekend afternoon REAL easy that matches your combo perfectly if you will simply take the time to find the information and actually READ IT.
Rat Bastid
Dunamis Metron
It’s even easier on an engine dyno. You can load it up and move the timing around while watching vacuum, torque and horsepower.
I have a 3 step retard in the shop that is going out Monday to get rewired. With that, I can sit at the desk and change the timing and know exactly how many degrees I’m moving it and watching the numbers.
Then you take that data and curve the distributor to get the curve it likes the best.
You can’t do that on an inertia chassis dyno (or the far more rare crank inertia dyno) because you can’t get a steady state load on the engine.
BTW, you can do the same thing when changing your emulsion/bleed package.
Well yeah, but ain't everybody haulin a dyno around. lol I've never understood the rebellion in doing it that way. The sky's the limit with the learning process. Maybe I should get the book out and do a how to video. I might if it wasn't made fun of. Look what they do to Uncle Tony.
Rat Bastid
Dunamis Metron
SCREW THE CRITICS and go for it. I was subscribed to your channel at one time. I know I never cancelled it so if the channel is still up I still get it.
Rob (@Rumblefish) has been putting out some really good, fun and interesting content. His stuff is always good and what he’s doing with Charlie Servedio is very good.
You never know who you might help with your video work.
TT5.9mag
Two atmospheres are better than one
You can change the values on x axis for map, kpa, and absolute psi
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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If your idle timing was optimized you might find that the engine likes 25/35 degrees at idle. If you set it there, with a typical stall convertor, the engine will bang the trans hard on engagement. The cure is to take timing out until it stops clanging the trans, and jumping the chassis.
The first time that Power-Timing is important is at stall.
and the second time is around 3500 rpm. So get that window figured out first. Then ramp the Stall timing DOWN, to whatever makes the trans happy at idle.
BTW
On my 11/1 carb'd 367 with alloy heads, she was no faster/quicker, on the Go-Pro SS with Power-Timing at 36, versus 32; so I run in the window of 32>34. and, She liked up to 60* of cruise timing with one combo I had. But with the current combo, all I give her is up to 54*@3400 or so, which with 3.55s and in direct (manual-trans), works out to 77 mph. However, at 65=2240 in overdrive, this drops to 48*typical, and 54*max with the dash-mounted, dial-back, timing module. These settings gets me max fuel economy.
My timing curve is linear from ~1000 to ~2800, when it hits the second spring that slows it down to all-in at ~3400. By delaying that last little bit, I can run 87E10 full-time without detonation.
My vacuum advance rolls in 22 Degrees as quickly as possible, which is all I could get out of her. A member here @TrailBeast got 24* out of his. This might help you. By setting your All-in to 34, and adding up to 24 or more for cruising, you can get at least 58*. If too much or not enough, only you will be able to determine.
The first time that Power-Timing is important is at stall.
and the second time is around 3500 rpm. So get that window figured out first. Then ramp the Stall timing DOWN, to whatever makes the trans happy at idle.
BTW
On my 11/1 carb'd 367 with alloy heads, she was no faster/quicker, on the Go-Pro SS with Power-Timing at 36, versus 32; so I run in the window of 32>34. and, She liked up to 60* of cruise timing with one combo I had. But with the current combo, all I give her is up to 54*@3400 or so, which with 3.55s and in direct (manual-trans), works out to 77 mph. However, at 65=2240 in overdrive, this drops to 48*typical, and 54*max with the dash-mounted, dial-back, timing module. These settings gets me max fuel economy.
My timing curve is linear from ~1000 to ~2800, when it hits the second spring that slows it down to all-in at ~3400. By delaying that last little bit, I can run 87E10 full-time without detonation.
My vacuum advance rolls in 22 Degrees as quickly as possible, which is all I could get out of her. A member here @TrailBeast got 24* out of his. This might help you. By setting your All-in to 34, and adding up to 24 or more for cruising, you can get at least 58*. If too much or not enough, only you will be able to determine.
Well then its not optimized.
As you point out.
That's just the old fallacy that advancing until maximum rpm in neutral is useful for something.
It doesn't work for the same reason timing for other throttle positions isn't set in neutral.
We know from experience 18 is about right for those cid and duration.
Well this where the ignorance sets in. If the engine liked 25/35 at idle, it will be making more HP [ because idle speed went UP ] at idle. The rpm will increase, the idle speed can theeeeeeen be lowered to a value [ often lower than it was idling with 12* initial ] to provide a better idle with more vacuum. The trans can now be put into gear at a lower rpm...& with less rpm drop. Vacuum is an indicator of idle engine efficiency at low rpms. Every wonder why that big cam will not idle under 1100 rpm......but the factory cam idles at 600 rpm....& with more vacuum?????
Increasing timing at idle from the nominal 12* increases vacuum.
Many GM cars had MVA from the factory & had well over 20* at idle with stock cams. My GTO left the showroom with 26* at idle & cam that had under 200* @ 050 on the intake.
Chrysler missed the boat.
Read this & learn:
Increasing timing at idle from the nominal 12* increases vacuum.
Many GM cars had MVA from the factory & had well over 20* at idle with stock cams. My GTO left the showroom with 26* at idle & cam that had under 200* @ 050 on the intake.
Chrysler missed the boat.
Read this & learn:
Rat Bastid
Dunamis Metron
Yup, a Pontiac and a chrysler take the same timing curves.
Not.
If you have to Jack that much timing into the engine to get it to idle you have a piss poor engine build, piss poor combustion chambers or both.
Rat Bastid,
Silly comments....as always. And wrong as well.......
If you have 'poor combustion chambers', there are two choices: find better chambers or work with what you have. Not all engine brands have choices in com chambers.
Silly comments....as always. And wrong as well.......
If you have 'poor combustion chambers', there are two choices: find better chambers or work with what you have. Not all engine brands have choices in com chambers.
Same ol reguritations, with a few new insults.
I don't wonder at all about why a 'big cam' has different timing needs than a factory cam.
Both queries here were about mopar engines, one stroked, one not. The stroke effects the piston dwell at top and bottom so has some influence on the effect of the IVO and IVC. Other than that we can go from experience. I saw no reason to guide someone in the wrong direction as they begin to tune their car. If the owner/tuner follows the procedure I suggested there is less chance of unneccessary hard engagement. More so if its a nose in garage. Remember going into N before R on cold starts with torqueflite? Same idea. Why slam stuff if it can be avoided? Whether Champy's 800 rpm input ends up where it current is, or at or some other timing will depend on the results he gets. It may be 25* but experience points toward something in the 17 to 20* range is the better direction to explore first.
www.forabodiesonly.com
I don't wonder at all about why a 'big cam' has different timing needs than a factory cam.
Both queries here were about mopar engines, one stroked, one not. The stroke effects the piston dwell at top and bottom so has some influence on the effect of the IVO and IVC. Other than that we can go from experience. I saw no reason to guide someone in the wrong direction as they begin to tune their car. If the owner/tuner follows the procedure I suggested there is less chance of unneccessary hard engagement. More so if its a nose in garage. Remember going into N before R on cold starts with torqueflite? Same idea. Why slam stuff if it can be avoided? Whether Champy's 800 rpm input ends up where it current is, or at or some other timing will depend on the results he gets. It may be 25* but experience points toward something in the 17 to 20* range is the better direction to explore first.
Distributor starting point for a curve
I get a lot of questions where my distributor curve should start this is a great guideline of different engine combinations and a good area of where the mechanical portion of the curve should be. I have been looking for something like this for a...
www.forabodiesonly.com
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You are still not getting it Mattax. The softest engagement for a TF [ or any auto going into gear from N or P ] is to have the engine making as much HP at idle speed. Stock engines do not clunk into gear with their 500-600 rpm idle because they are making enough HP at THAT rpm to sustain the engine at idle. Big cams will NOT idle at very low rpms because they are not making enough HP to sustain engine operation at idle. In this situation, giving the engine more timing at idle produces more hp & allows a lower idle rpm than it would with the factory 12* BTDC. MVA is a simple & effective way of adding the reqd timing.
This is from Mopar Muscle Oct 15
This is from Mopar Muscle Oct 15
Or SERIOUSLY LOW cylinder pressure. There was a reason Pontiac had almost ZERO street cred off the showroom floor during the muscle car years. They were slow.
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