Timing tips

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Yeah, that trips a lot of people up. It's not actually vacuum on that axis, it's pressure (absolute pressure to be more specific).
So the top of the chart is wot. Usually what I see is whatever the motor wants at peak torque it will want the same or a little more above that rpm.. Is the timing 18 deg. at wot 6500?
 
Yep, it's 18 degrees at top end. I think it can probably take more, but I've just been careful to creep my way up there since I know the ring lands on the stock 5.7 pistons are known to be a little weak to detonation and I'm running lower octane. I'm guessing it can probably take 20 or more, but I wanted to start small and work my way up. 18 is also close to what the factory table used around peak torque at least. The MSD tables run up to 17 or so around 3500 and then drop 15 the rest of the way out. The factory table ramps to 18 around 3000, dips to 16 for 1000 rpm or so, then ramps back up to 24 at the top end. The EFI Source table runs right up to 23 at 2500 and pretty much carries that all the way out to 6500, dropping 1 degree along the way.

The factory rating was also 345 hp @ 5400 rpm and 375 ft-lbs @ 4200. I know my cam and intake are likely going to move those peaks around though. The short runners on the intake would have me thinking the rpm band has moved up though I'm less sure about the cam, so I'm thinking that's one reason the dip in the factory table really didn't suit my combination well. The flatter timing of the EFI Source table seems to be a better fit. I've only ever dyno'd the car once with the previous MSD setup. It was nothing special, only making something like 280 hp and 290 ft-lbs at the tires. Torque actually peaked pretty early at 3250 or so and power was around 6000. I don't remember what timing and fueling I had at the time, though I'm guessing they were on the conservative side. I've also had it at the dragstrip once and threw a few extra degrees at it between runs. I'd have to try to find the timeslips, but I think my best time was something like 13.5 or 13.7. Don't remember the mph off the top of my head though.

And regarding the intake, yeah, when I first had it on the car I had it with a carb. There weren't many carb intakes on the market when I did my swap originally, and it was the more affordable option. I never did get the carb to run well with it. It would cruise okay, but a full throttle stab would just make it fall on its face. I had a Carter AFB on it and was going to try changing to a double pumper setup thinking that the extra fuel shot might help, but I ended up converting back to fuel injection when I got my Megasquirt setup used and super cheap. I had already sold the stock intake at that point though (ironically the guy I sold it to gave me the tip on the Megasquirt as he knew the guy selling it). I bought the bit to drill the injector holes and took it to a buddy's house who had a mill and we chucked it all up and set it up for injection. Runs much better now for sure.
 
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I've got the cam card here. The short version is 267/275 intake/exhaust duration and 0.549/0.536 lift intake/exhaust. LSA is 110 as it turns out. It says 4 degrees of advance ground in. 106 intake centerline and 114 exhaust.

In at 106 the rest of your cam events look like;
267 intake/120.5 compression(Ica of 59.5)/108.5extraction/275exhaust/51* overlap
FYI
I ran a FTHcam in my alloy-headed, 11/1, 367LA(6-liters), very much like that;
270 intake / 119 compression (Ica of 61)/ 108 extraction / 276 exhaust/ 53* overlap
I have run three cams in this engine..... so far; and this one, by far,was my favorite. @3650 pounds, car went 106 with that combo, first time out. She had enough power to spin the 245s tires thru two gears at least; usually to 60mph or more. I very quickly fit 295s back there, then 325s.
With his engine, I ran a Mopar A833od with a GVod/splitter behind it and 3.55s. The ratios were
3.09-2.41-1.67-1.30-1.00-.78-.55....... splits in red. Yeah, I know, seven useable ratios with nice splits. With this gear combo, 65mph was; 2870 in direct/2240 in GVod/1590 in double od.
Here comes the point;
It got no better fuel economy at 1590 than at 2240. Engine vacuum was higher at 2240, and I could get the timing closer to what it wanted; which was over 56degrees for cruising. The Distributor kicked in 45 degrees and my dial-back could add back, up to 15, for a total of up to 60.
But; with a manual trans and a starter gear of 3.09 x 3.55=10.97, the slowest I could drive with 14* idle-timing, was about 5.1 mph, before the engine started bucking. This is too fast to walk beside. I found that by retarding the timing to about 5*, the engine could maintain 500 rpm pulling it self along at 3.6 mph, which is what I needed. So that means, from 14, I needed to set the Dial back to 9retard leaving just 6 for advance. Therefore my cruise timing would have to be 45+6=51, close enough.
After I figured out that I more or less had a useless seventh gear, I installed 4.30s to cruise at 65=1930 in Seventh/ double overdrive. This gave me a starter in which 550 was 3.3mph. I was able to swap 3 degrees from retard to advance, and now ran 45+9=54* @1930rpm.
All this to say;
1) I know nothing about hemi's
2) I know a lot about tuning my 11/1 alloy headed 367LA. I have run 3 different cams in it.
2a) I know with a manual trans, mine does not like a lot of idle-timing down real low, but
2b) by 2800 it likes at least 28* for power, and
2c) is satisfied with 32/34 at WOT, and I delay it to ~3400 to keep it out of detonation on 87E10,
2d) and it likes a chitload of cruise-timing; at least 56*. My vacuum advance is set up to pull in 22*, and while it's enough, the engine really wants and responds well to in the range of 56 to 60 degrees@ about 2240 rpm.
BTW-1;
I no longer run this combo. The cam died. And I came to the realization that 7 useable gears in a streeter was about two too many. I now run a cam one size bigger. And she is back to 3.55s/ but now a Commando trans(3.09low), still with the Gvod, and turns 65= 2240
BTW-2;
I ran/still run 87E10 full-time in this 11/1 367 with alloy heads, with no sign of detonation ever and, I took it apart 5 winters in a row looking for it. Pressure was 185 with the smaller cam, now ~178.
BTW-3;
looking at this;
In at 106 the rest of your cam events look like;
267 intake/120.5 compression(Ica of 59.5)/108.5extraction/275exhaust/51* overlap
There is nothing that I can at all see problematic in terms of tuning it.
BTW-4;
If your dual throttle bodies are NOT progressively staged;

I'm pretty sure your cruise problem is gonna eventually trace down to that. The cam you have wisely chosen, when coupled with high cylinder pressure, is very powerful down at cruise rpm, and wants only a tiny amount of throttle opening at ~2200 rpm. I was able to squeeze 32mpgs out of mine on a certain test-run. I used an adjustable, over-rideable, throttle-stop to help me keep a steady foot, on the primaries of a Holley 600 no less, just to control the throttle opening exactly..
With EFI, if the throttle opening wavers at all, your AFR is gonna jump around in lock-step with the wavering throttles. No amount of timing shenanigans can deal with that. So, it is my hope that your TBs are staged.
BTW-5
that cam, with a manual trans, in my 367, liked an idle speed of at least 650/700 was better. And it liked in the neighborhood of 24* at idle. Obviously, with a carburator, and a manual trans, that would be a disaster. I compromised at 12/14 degrees@700; but down at 550, I had to cut her back to 5* to prevent bucking; because the AFR with a carb is hard to control down there and at 550@14* the engine is already making too much power to accurately control, she is chomping at the bit, eager to be pulling. I had to hobble her a bit.

Ok so, hope this helps, and
Happy HotRodding.
 
So I can make things a little easier in that I actually only have a single 4 bbl throttle body instead of the duals. That was just the best picture I could find that showed the fuel rails. That being said, I think the front and back bores are all on a common linkage with no staging if I remember correctly, so all four open together at the same rate.

The manual trans is a blessing and a curse. On the one hand I think it gives me some more room for idle tuning to get what I want and like, but on the other getting the transition right when I first take off has been tricky. It likes to fall a little flat if I let the rpm drag a bit too much and then pops back up and does have some low speed buck to it. Not nearly as bad as my cammed Viper. I'm guessing I can get that sorted out with some timing tweaks, but it's just hard to see what's going on while I'm doing it and a datalog isn't really quite the same as sitting in the car feeling it. It would probably show up in the rpm or VSS as some jerk though, so I might be able to visualize it.

I also just ran my combo through an old engine simulator (Desktop Dyno 2003) for an idea of the theoretical horsepower and torque peaks so I'd have an idea where my combo might have moved stuff around. It's showing about 375 hp at 6000 rpm and 400 ft-lbs from 3500-4500. Seems reasonable to me, though maybe a tiny bit lower than I would have hoped for overall numbers. That being said, it should make a pretty nice street car.

Fueling is always the easy part of EFI tuning. You have a set value to shoot for and can even autotune to get there nowadays with a wideband sensor. I wish it was possible to do the same with timing. I guess with knock sensors you sort of can, but it's not really the best way and still risks hurting things worse than a rich or lean tune. I think I will look at getting the knocksense module to incorporate the stock sensors though. I think it was cheap enough and I'm pretty sure I still have the factory sensors bolted on.
 
All of the problems I’ve read about the modman intake seem to revolve around that intake being used with carbs and wet flow. I don’t think that is your problem. I do think the g3 hemi is sensitive to timing but I think most out of the box ignition maps are extremely conservative. Looking at your map, and pulling from my little brain having tuned a variety of different engines, you’re going to end up with considerably more cruise timing at low loads, and a couple to a few more degrees throughout WOT with a 1-3 degree dip around the tq peak. If it were mine, or I was tuning it, my absolute first step would be to wire up a functional knock sensor. Listening for detonation will end with shattered pistons. Then I would dump some 91 in it and press up against the knock threshold, and back it down 1-2 degrees. Then go after mpg in the low load areas of the map. After that you could create an 87 octane map (-30%) and put it on one of your switchable ignition tables. Without a knock sensor or being on a dyno there is really no way to know how safe or dangerous the tune is or what the engine actually wants. That’s just how I’d do it.
 
All of the problems I’ve read about the modman intake seem to revolve around that intake being used with carbs and wet flow. I don’t think that is your problem. I do think the g3 hemi is sensitive to timing but I think most out of the box ignition maps are extremely conservative. Looking at your map, and pulling from my little brain having tuned a variety of different engines, you’re going to end up with considerably more cruise timing at low loads, and a couple to a few more degrees throughout WOT with a 1-3 degree dip around the tq peak. If it were mine, or I was tuning it, my absolute first step would be to wire up a functional knock sensor. Listening for detonation will end with shattered pistons. Then I would dump some 91 in it and press up against the knock threshold, and back it down 1-2 degrees. Then go after mpg in the low load areas of the map. After that you could create an 87 octane map (-30%) and put it on one of your switchable ignition tables. Without a knock sensor or being on a dyno there is really no way to know how safe or dangerous the tune is or what the engine actually wants. That’s just how I’d do it.

Fair enough. That's kind of what I'm looking at now. A knock module for the MS3 is only $90, which is probably cheap insurance in the long run. I've already got the stock sensors as well, assuming they actually still work. The one thing that is getting me is the transition from high speed low rpm cruise to high rpm power. I'm right at the very edge of my rich power section on the table. My AFR is basically 14.7 everywhere to the left of 2500 rpm and below 70% load or so, going to up 15 in the even lighter load sections. Then the top right corner is 12.7 from 70-100% load and 2500 to 6500 rpm. My high speed cruise in 6th puts me right at the bottom left corner of that, so if I bump the cruise timing way up I'm not sure how the engine would like a 5+ degree drop in just a few hundred rpm. That being said, I guess as I got some more timing in it I actually dropped my load some. It used to take 80-85% load to do 70 in 6th and now it's down to 70-75% with the few degrees I've already added. It's just a very iterative process. A dyno would make it so much easier, but I'll see what I can do with just logs and seat time for now. Thanks for all the advice so far!

And I think I agree about the Modman issue with carbs. To me it seemed like the plenum volume just didn't do fuel mixtures any favors. I don't think you got much runner velocity on a quick throttle hit. Multiport injection certainly helps the atomization problem and then the runner is just about straight up flow and not fuel mixing. I was actually pretty surprised the difference between batch fire and sequential as well. My idle was never consistent before (though I think a little of that was I didn't play with idle timing on the MSD much) and I'm guessing the cam didn't help with possible reversion. Having fuel at each cylinder as that cylinder needs seems like it would help keep that under control.
 
>If in fact the secondaries are running loc-step with the primaries, that is the very first thing I would change. With that small cam, and a manual trans, I can't imagine that to be much fun. IMO, you would have to severely limit the low-rpm timing to not have an on/off switch type of performance, down there..
>With an Ica of just 59.5, Your vacuum should peak pretty early say 1800rpm maybe a lil less, so once past that, you shouldn't have any reversion problems. And honestly, IMO you should be getting an idle-vacuum near 13 inches, or more, already@700. If under 12 @700, I would be looking for a vacuum leak.
>I modded my V-can to get 22 degrees, and it comes in/ goes out, almost as fast as possible. If I lift throttle, Pow it's all in. If I roll on the throttle it drops out. At Part Throttle I can dial it in or out, anywhere between zero and 22 degrees, which makes for a generous amount of low-rpm PT torque.
The engine never complains. Transitions are seamless. It's like EFI without the stinking electrics.
> IMO, if you are trying to cruise at 65=1450rpm in Top gear, with that cam, you may never get the tune right down there; and she will never get the mileage that she will at say2000/1800. ESPECIALLY with all 4 throttle valves opening simultaneously; the vacuum is just too unstable; the tiniest throttle change will throw the tune into a fit..
IMO, you gotta cruise at an rpm that has shut the door to reversion, and with a solid vacuum signal that does not change much with small throttle-openings.
>When I did that 32mpg run, I used a tiny Holley 600VS, with the secondaries defeated (so I could use ALL of the primaries to get up to speed if I needed to), and dialed very lean, with massive(lol) amounts of cruise timing (up to 60*). The trick is that at cruise rpm, the vacuum signal remains steady; if the vacuum is hunting around because the 4 throttle valves are waffling around, your computer is gonna change the injector-on time,(and maybe the timing) and your O2 is gonna have a fit. I doubt it can keep up. At 1450rpm, your engine is doing 24 revolutions per second; at 4 injection events per revolution, is 96 events per second. How fast is your O2?
 
Fair enough. That's kind of what I'm looking at now. A knock module for the MS3 is only $90, which is probably cheap insurance in the long run. I've already got the stock sensors as well, assuming they actually still work. The one thing that is getting me is the transition from high speed low rpm cruise to high rpm power. I'm right at the very edge of my rich power section on the table. My AFR is basically 14.7 everywhere to the left of 2500 rpm and below 70% load or so, going to up 15 in the even lighter load sections. Then the top right corner is 12.7 from 70-100% load and 2500 to 6500 rpm. My high speed cruise in 6th puts me right at the bottom left corner of that, so if I bump the cruise timing way up I'm not sure how the engine would like a 5+ degree drop in just a few hundred rpm. That being said, I guess as I got some more timing in it I actually dropped my load some. It used to take 80-85% load to do 70 in 6th and now it's down to 70-75% with the few degrees I've already added. It's just a very iterative process. A dyno would make it so much easier, but I'll see what I can do with just logs and seat time for now. Thanks for all the advice so far!

And I think I agree about the Modman issue with carbs. To me it seemed like the plenum volume just didn't do fuel mixtures any favors. I don't think you got much runner velocity on a quick throttle hit. Multiport injection certainly helps the atomization problem and then the runner is just about straight up flow and not fuel mixing. I was actually pretty surprised the difference between batch fire and sequential as well. My idle was never consistent before (though I think a little of that was I didn't play with idle timing on the MSD much) and I'm guessing the cam didn't help with possible reversion. Having fuel at each cylinder as that cylinder needs seems like it would help keep that under control.
Your quote about the load dropping off as you increased timing seems to verify my thinking. The load going down at the same throttle opening/speed tells me the engine wanted the extra timing. That’s exactly how you tune it without a dyno. The vacuum gauge becomes a very important tool. On the transitions between cruise and WOT throttle, as you get the timing closer and closer, go back and use the interpolate function in between those cells and let the ecu do the work. It helps a bunch.
 
Yeah, I'm thinking I might just find myself a copilot to drive the car and I'll sit in the passenger seat and dial up timing as we cruise along and different speeds and gears if I can find long enough stretches of road that are either flat or have constant grade. The poor man's dyno if you will. Might try to get the knock sensors running on it before then though. They are out of stock on the module that goes in the computer at the moment, so not sure how long I'll have to wait. I guess I could get them prewired while I wait at least.
 
Can’t you tune off of a datalog?

I'm not sure if a datalog is going to show me anything without a knock sensor. If I had one I think I probably could as I'd be able to check knock against the timing table, but without one I'm not sure what I would compare the timing against. My thought was more if I can get the engine operating at a steady state I could change timing on the fly and see what effect it had. If it likes it I would expect the speed to increase slightly as the engine would be making more power at the same conditions. If it didn't I would expect the speed to drop. Effectively like running the car on a dyno at a constant load and adjusting timing, just doing it on the road instead.

I could maybe do something similar with a datalog where I do a run at one setting, change it, then make the same run and compare the load between the two, but I feel like it would be much easier and more productive to do in realtime as there would hopefully be less variability between runs at that point.
 
Real time tuning is the way to go but studying a datalog and making changes with some thought is pertinent as well. As with any parameter you set a target, run a datalog, look at the trace compare to target, adjust and repeat. Just make sure you’re logging the correct channels and it easy peasy.
 
wow you run the same timing or similar as i do being turboed.
what is done to your heads, anything? softened chamber maybe? each ecu may be resistance indifferent as the last ecu you used. resistance casued by mulyiple things such as wiring length, resistor sizes, board curcuit load capabilities etc..
i literally kust switched my dash to show timing in real time on my holley pro dash. ive seen as high as 28° free reving and drop to 0° finding idle after reving. (my **** runs to fat at idle). i am on e85 and have softened combustion chambers on my heads. which possible good be that timing abnormality between our 2 differing setups. just offering food for thought.
 
I've since changed it quite a bit and it seems to be a fair deal happier. This is the new table I'm running at the moment:

New Timing Table.jpg


It's more like the EFISource table with the idle position adjusted to my car and the bins changed around a little bit. It's way happier on this one and will cruise on the highway fine like it used to. Also has some more zip to it for sure, though I still think it's likely got more to give if I want to push it. I also got away from using the two different tables for the time being. My initial setup used something similar to the factory with an "open loop" and "closed loop" table, though really for me it was more <80% TPS and >80% TPS since with a wideband I'm kind of "closed loop" all the time. That's the main reason there is the big hole in the upper right. If I had the dual map setup going this table would be smooth all the way across and the second table would be where the timing is taken out for hard throttle hits, but for the time being I figured it was easier to tune a single table. Now I cruise on the highway around 27 degrees of timing and it seems like it likes it well enough.

I don't really like the huge hole at idle, though I'm not sure if it really matters or not. I can actually set up an idle advance table in the Megasquirt so that the engine swaps to a much smaller table (it's only 4x4 or something like that) whenever it's in the "idle" state, but I'm not sure if it would actually work or not. The main reason I think it might not work well is that if I take the hole out of this map and bump all the timing back up so it's a smooth curve, the engine will idle really high (it's basically like 20 degrees of advance at idle), and if it's idling high I don't think it will ever drop into the closed loop idle. I may still give it a try someday, but for now this is running well enough. I plan to try to get the knock sensors working as soon as I can get my hands on a knock module, and at that point I think I'll probably see about bumping up the WOT timing numbers.

The other thing I've thought about doing is reverse engineering the timing map in my parents' Ram. It's a 2016 or something like that, so it's not apples to apples since it has the 09+ heads and the VVT, but I'm thinking it would still be interesting to see and compare against. I have a bluetooth dongle and should be able to datalog with the Torque app on my phone, so I could try to rebuild the map. The more I think about the "factory" map that I had, the more I'm not convinced it was really the final timing number at any given point. I feel like there might have been other modifiers affecting the final timing value and that the map I had was just a base that gets added or subtracted from. Datalogging realtime would let me see actual commanded values at any operating point.
 
Actually, after thinking about it some more I think I should probably just get rid of the hole around idle anyway. I was thinking back to tuning the distributor on my 71 Vette and realized that you set base timing with the vacuum advance plugged, and base timing is usually around 12 degrees or so. However, when you plug the advance back in, you may end up around 20 again. This table isn't base timing, it's got the vacuum advance built in, so I should probably be around 20 degrees or so when idling. I may give that a try later today and see if it helps the slight stumble when slipping the clutch to take off. I'll have to readjust my throttle plates, and hopefully I've got enough left in them to close to pull the rpm back down.
 
Actually, after thinking about it some more I think I should probably just get rid of the hole around idle anyway. I was thinking back to tuning the distributor on my 71 Vette and realized that you set base timing with the vacuum advance plugged, and base timing is usually around 12 degrees or so. However, when you plug the advance back in, you may end up around 20 again. This table isn't base timing, it's got the vacuum advance built in, so I should probably be around 20 degrees or so when idling. I may give that a try later today and see if it helps the slight stumble when slipping the clutch to take off. I'll have to readjust my throttle plates, and hopefully I've got enough left in them to close to pull the rpm back down.
I agree you will want more timing at idle. Do you have an option to look at the chart in inches of vacuum instead of kpa? Also can you see the value kpa or in. hg. live? How much vacuum does it have at idle? Kpa and in hg.
 
Not sure I can adjust the scale, but doing the conversion it idles around 16 inHg. Really the chart is almost a direct kPa reading already, just in absolute pressure instead of gauge. To convert basically just invert the scale so the top is 0 and the bottom 100. That would put the idle at 45-50 kPa of vacuum.
 
Not sure I can adjust the scale, but doing the conversion it idles around 16 inHg. Really the chart is almost a direct kPa reading already, just in absolute pressure instead of gauge. To convert basically just invert the scale so the top is 0 and the bottom 100. That would put the idle at 45-50 kPa of vacuum.
Can you adjust timing while it's running at idle? Advance until it no longer makes the motor "happier" then back it up a little and test it in out of gear and at low speed high vacuum driving and see how it drives. Can you log the vacuum to get a feel for how much vacuum the motor has at different driving scenarios?
 
Yeah, I can tune on the fly while it's running and log it easily. Bumped the idle timing up to 20 degrees and surprised it didn't make more of a difference in rpm, but I think it did help my stumble issue. I think what was happening there was the timing would pick up when I would blip the throttle before starting to slip the clutch, then as the rpm fell as the clutch engaged it would drop back into the low timing zone and the engine would lose power and stumble.
 
Yeah, I can tune on the fly while it's running and log it easily. Bumped the idle timing up to 20 degrees and surprised it didn't make more of a difference in rpm, but I think it did help my stumble issue. I think what was happening there was the timing would pick up when I would blip the throttle before starting to slip the clutch, then as the rpm fell as the clutch engaged it would drop back into the low timing zone and the engine would lose power and stumble.
You have an IAC right? The iac will try to maintain a target so it may be compensating for the increased idle rpm.
 
Yeah, I've got an IAC, but it was at the very bottom of the travel the way I had my idle set up before. The goal was to have it as close to fully closed as you can get it when the engine is hot. They tell you to set the throttle blade stop just barely under that so you don't stall if you clutch in and coast, but you want as much IAC travel as possible. Looks like the extra timing really didn't make as much difference as I was expecting though. Small changes on the throttle stop seem to have a bigger effect, so I had plenty to work with as it turns out. I'm curious to see if this will help some of my warmup driving issues as well.
 
I use the idle advance feature on mine and haven't had any problems with it. The nice thing about it is you can either make your engine sound like it has a big lumpy cam or tame a cam. For a smooth idle, you basically reduce timing when RPM goes up, and advance timing when RPM goes down. You will see the "bubble" moving across the timing table rapidly if you have a rowdy cam. I was able to fine tune my idle to where my rpm only oscillates about 50 RPM. That is only seen on the digital tach on tuner studio. On my dash tach, its stable as a rock. I would recommend using idle advance.

I also use the idle RPM correction curve. This helps adjust the idle faster than the slow moving IAC. You do have to get your IAC pretty close as the RPM swing (at least on my engine) isn't as large as the swing with the IAC. This helps when the engine is returning to idle.
 
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