Grumpy

Take a SBC, punch it to 355, install with some 3.00ish gears, 700R4 tranny, 2,600 stall converter, run it off of a BBC Throttle body, with 85 pph injectors, Comp Cam 270 cam, 9:1 CR, 58cc AL heads, and you just might see a table that works well that looks similiar to this.

Do not use this table, it is just an example. I have my own method for my madness with AE and VE tables to cover this.

Bigger cam self EGR at idle so notice the 28d timing there.
No need for timing at overrun and to help the car roll down better, I knock the timing way back
This includes initial timing, notice not alot of timing, not needed with the small chamber heads.
Timing is relatively flat from max Torque to max HP.
No need for highway spark, we got enough timing for a lean cruise AFR anyway.
Notice the second you get out of the cruise MAP area the timing drops out quickly!!.


MAP is from 20-100 reading left to right
RPM has idle at the top, and high RPM at the bottom


28 28 28 28 24 20 20 20 20 20 20 20
25 28 28 28 24 20 19 20 20 20 20 20
25 28 28 28 24 20 20 20 20 20 20 20
20 30 32 29 27 24 22 22 22 19 19 10
16 33 40 38 34 28 24 20 14 14 12 12
16 34 40 38 38 28 24 20 18 16 14 14
18 36 40 40 38 30 24 20 18 16 14 14
18 36 40 40 38 32 24 24 18 16 14 14
18 36 40 40 36 32 28 24 18 16 14 14
20 36 40 40 36 32 28 24 20 18 16 16
20 36 40 40 38 32 28 24 22 20 17 17
20 36 40 40 38 32 28 24 24 23 18 18
20 36 40 40 37 32 28 26 24 23 19 18
22 36 40 40 37 34 28 25 24 24 22 22
30 36 40 40 37 34 28 26 24 24 24 22
38 36 40 40 36 34 30 26 26 24 24 26
38 36 40 40 36 34 31 30 28 26 26 26


Again, this is just an idea of what things might look like. WAY TOO OFTEN folks get turned around on what a hipo curve might look like.

DM91RS

The DFCO is the part of the fuel table that you also want to cut down as well as timing?

Am I understanding this correctly Grump?

ski_dwn_it

Grumpy,
Thanks for the info. Do you zero out the Spark Advance in WOT vs RPM? Your table names are probably different than mine. Here is my table do you see anything grossly out of proportion? I realize my idle is way off from what you suggested. I will try one with it higher like yours. Currently I have the car running consistantly in the mid 12's and it is running PIG rich. I am afraid to mess with the fuel till I build my WBo2. Should have time shorty. Do you suggest anything?

17.9 17.9 17.9 17.9 17.9 19.0 20.4 21.8 20.7 20.0 20.0 20.0
16.2 16.2 16.2 16.2 16.9 18.3 20.0 20.7 20.7 20.0 20.0 20.0
15.5 15.5 15.5 15.5 15.5 17.9 20.0 21.1 22.1 20.7 20.7 20.7
17.9 21.1 24.6 24.6 26.0 25.7 22.9 22.9 22.9 19.0 19.0 25.0
19.0 23.9 28.1 27.8 27.1 22.1 19.0 17.9 17.9 16.2 25.0 26.0
19.7 26.0 30.9 30.9 30.9 28.5 23.9 22.1 22.1 19.0 25.0 26.0
21.1 35.9 35.5 34.5 33.8 33.0 29.9 26.0 23.2 26.0 28.1 28.1
22.5 33.4 35.9 35.9 35.2 34.5 32.7 26.0 23.2 26.0 28.1 28.1
22.5 33.4 35.9 35.9 35.9 34.8 33.4 29.9 26.0 28.1 28.1 28.1
22.5 33.4 35.9 35.9 35.9 35.9 34.5 32.7 28.8 28.1 28.1 28.1
22.5 33.4 35.9 35.9 35.9 35.9 35.2 28.8 26.0 28.1 28.1 28.1
22.5 33.4 35.9 35.9 35.9 35.9 35.2 27.8 24.3 28.1 28.5 29.2
22.5 33.4 35.9 35.9 35.9 35.9 33.0 27.8 23.2 28.1 28.5 29.2
25.3 33.8 38.0 38.0 38.0 35.9 32.0 26.7 24.3 28.1 28.5 29.2
25.3 26.7 29.9 33.8 33.8 35.9 32.7 27.8 25.3 28.1 29.2 29.2
25.3 33.8 38.0 38.0 38.0 35.9 32.0 27.8 24.3 28.1 29.2 29.2
33.8 40.1 40.1 40.1 40.1 38.0 35.2 32.0 28.8 28.8 29.2 29.2

Thanks. Jesse

Grumpy

There are numerous DFCO setups.

For the way I drive, I like the car to oll down as fast as possible.

It's going to vary by car what you do. For some you'll want to leave some DFCO, others not, some with alot of timing, and some with little to no timing.

On the GN for normal street use, I run DFCO, and turn all the fuel off. On cruise night, or off road racing, I leave the fuel one and run the timing to like 10d ATDC, in effect an anti lag strategy. Leaving the fuel on and timing retarded, generates a real crackle in the exhaust.

Grumpy

Over the years, I've learned not to develope the reputation of doing cals for other folks.
What I will do is show what I'm doing and explain what it is that works for me, but everyone is on their own for develoing a cal that works for them.

In general I don't run much if any PE spark adder. Again things vary by application.

tpi_roc

I really hate to bring back an old topic, but the final answers are the money pots. My search always brought me to this thread anyways, so I'll make it just a tad longer hopefully with some more of grumpys wisdom.

I noticed grumpy that yours and Skis tables will idle with relativly high advance, then slop down (for the stall speed?) and then climb back up till the table maxes out.

All the stock bins that I've ever looked at would add another "Hump" in the curve. Idle high, then go lower (pre stall) then raise ( stall) then lower again (post stall) then raise untill the table climbs out.



Whats with the second "Hump" ? Is there something I"m over looking, i can see the timing curve around the stall area but why did gm have so many compared to what would seem "right" and what you two are running for spark advance tables?

I would say maybe highway mode, but ARAP does the same thing and it doesn't have highway mode...

Anywho, maybe someone should just lay out their reasoning for the way they're doing their S/A tables?

Grumpy

I can't explain why GM or why even you table might look different then mine. BUT, I can tell you,

I gave the engine what it wanted, and it runs really well like this.

tpi_roc

Man thats what I get for my efforts


So you have no theorys on why the spark table would make this "sine wave" kinda curve?


Where SHOULD the first timing hump be? during, before, or after the stall?

Grumpy

I know it would make life real easy to say here's the perfect timing table and be done with things, but it just ain't so.

Theories, ya gots of theories, trouble is with them, they can hold you to what's not universally true. You have to keep an open mind with this stuff. Do the experiments, and repeat them til they are repeatable from car to car and then you can draw out the truths. It's like one guy saying something that works for his car works, there for it must work for all. Sorry it just doesn't work out that way.

Converters are very hard to work with.
Yes, you can run alot more advance then I typically do below the stall speed of the converter, but the down side is lots of tire spin, and a finicky running car. A conveter gives you about an extra 2:1 in gear multiplication, below it's stall. Which is enough to just blow off the tires, and spinning tires don't move the car.

You just have to dig in and see what the engine wants. I wish I could make it easier to do, but it ain't. With practice thou, it gets alot easier.

tpi_roc

Well as insight to my scenerio, I'm having rediculous amounts of traction, hell I can't break them loose (without the use of the brake) at any point. I've been adding timing and timing and timing, it almost seems now like there's alot more than you say the engine will typically take (I'm as high as 35° in a WOT run) and I still have 100% traction. I'm not looking for a smoke show, believe me I know the value of traction and am enjoying it, but also i'm not making the power I should. I'm trying to figure out what ENGINES want, so I know what MY engine wants. Then I ran into everyone having one timing hump, then cross refferencing that to GM stock bin with 2 humps, and I can't figure out the practical use for it. I was currious, and I using the information you've gained over the years gets me 2 rungs up the ladder for my starting point, I'm not looking for a freebie, I never am. I dont plan on running a universal timing curve, otherwise why would I be "tuning" and I dont want to run YOUR timing curve.

I simply need more timing theory to try to base descisions and direction in my tuning efforts hopefully minimizing the amount of research on my part that other people have already done, and being able to move forward from that point hopefully in the end gaining ground.

ski_dwn_it

I am sure that you have already checked this but here it is anyways. Have you checked for knock?

My post is in there somewhere too where I was having the same exact problems. Needless to say, I disconnected the knock sensor. MADE absolute sure that I was not getting knock, SP checks, etc. My problem was cured. Now this may or may not be the case with you. I am still running not all that much timing, but I was able to increase in areas that I really did need it.

I think the point that Grumpy was making is it is hard for anyone to say why there is one hump, two humps, etc. I quite thinking about what I was *doing* to the car long ago. Or I should say trying to rationalize out each change. If it needed fuel it needed fuel and I gave it to her.

Here is one for ya to think about. I have logs of my stock setup. I had that tuned to have 128 BLMs across the boards. Never touched the WOT fuel curves, did not have a WBO2 to verify the changes. Actually never touched any of the fuel curves.

I had approxiamately 160 g/sec at 4000 RPM with the stock setup and 240 g/sec with my new SR and AFR heads at 4000 RPM. Now you would tell yourself that with the same chip, you would be terribly lean, since you are dumping more air in than ever before. WRONG! With my WB hooked up I was running 10.1 AFR with the SR setup and the same chip. I actually went to a dyno just to verify the readings I was getting with my WB. Sure enough the two WBs were one for one.

Leaned the car out and holy toledo. Throttle response and everything was better.

I guess what I am trying to convey is use your head to make decisions, but don't dwell on the things that others say work and don't work. You have to experiment and error on the side of caution if things really seem messed up. Take the WB readings for example. I made sure mine was reading right before trusting it, but once that was verified. Go for the change.

All in all, reading these post are very helpfull and many of us would not be where we are at now without them, but they are not gospel. They are just very broad guiderails.

Good luck...Hope you get it smokin!

Grumpy

If you keep adding timing and timing then maybe your going in the wrong direction.
Maybe just take a deep breath, go to you base bin file and start again.

I can't tell you how many times, I do that.
There just ain't no simple answers for things. Tuning is alot of hard work, and like many other things, it does seem to be more nature for others then some. Single double, triple Sine waves, are something, I really havn't paid any attention to.

tpi_roc

Great response ski, I always look forward to your "down to earth" posting. I certainly dont plan to take any of it for gospil since I plan on finding most of it out myself, but who knows, chopping off one of those "humps" in the spark table could net immediate results. As far as spark knock other than the phantom knock (I have a post or two about it that haven't gotten replies) I dont have any knock counts, Im running about 9.5:1 compression, cast heads, and 6° base timing, on 92 octane pump gas. I have been adding timing (about 7° to the ENTIRE table now) and still not seeing knock. Where did you find the most bennifit to aditional spark? under or over the stall? Would you mind if I had a look at your most current timing table?

Also If you wouldn't mind, in comparison (yes im taking endless plug cutts) but I'd like to know what your stock 02 reads in MV when you're getting about 12.0:1 AFR on the wide band.

tpi_roc

I did end up realizing something about my "sine wave" observation. When I say that I'm looking at the timing table from low rpm to high rpm on a single LV8, and when you're accelerating you're crossing LV8's diagonally, however when I checked into that I still do see a camel hump to the timing. I did pretty much try to "start over" I started with a stock ARAP, played with it. Then went to a AUJN timing table with ARAP base (for MAF cal) and that took care of the ARAP knock, gave more power. Then I started adding timing to the ENTIRE table, and took timing out of PE spark vs RPM and I *feel* (for what its worth) a much stronger lower end pull, still no knock.


Now I know this is a question you dont even want to answer I've seen it endlessly avoided by the more knowledgable members of this board, But I'd like to answer looking for a stricktly hypothetica/theoretical response.

Say you have a bin you JUST started using, you have no idea what your engine likes/needs. To get yourself into the money zone and closer to your appropriate timing curve, would it be appropriate to start with conservative timing (assuming A/F ratios are all good) and slowly add timing at all RPM's untill you find where it begins to knock at a given R and stop, and back up a few degrees, basically ending with an entire timing table where all loads/rpms are just 3° short of knock, and then tune for "What the engine wants" From that point? So you know you're not under timed somewhere?

This is basically what carb guys have been doing forever, would it not make sense to help find out where your engines limits are this way?

tpi_roc

Grumpy

Bingo, you're getting it!

Depends on your way of tuning. I perfer to take the time and go slowly keeping the engine out of detonation as much as possible. But others seem not to care about how much detonation the motor sees during tuning. Also in going in small steps you're much MUCH less likely to bomb right on by the best combo.. Missing by 3+d can send you down many false trails.

tpi_roc

Finally getting somewhere

ski_dwn_it

Tpi,

I think your getting the hang of it. Here is another one that will blow your freakin mind that happen to me tonight! I just can't win. It deserves its own post, but I am 99.9% sure this is why I was getting false knock. How hard would have this been to find?

Here is the situation. I have a new tranny on the way. Since about 1 month after putting this setup together, been ~4 months now, I have been having an oil leak that I just could not get to stop. I replaced the front seal, oil pan gasket, etc. Tonight I decided to pull the balancer once again to change the front seal, because some very close watching definately pointed at the very front of the engine as the source of the leak.

It takes me about 1.5 hrs to get the balancer off. Since about the only way to get the front seal out is to tap a screwdriver through the existing seal and twist is out I begin. As always it pops right out. I begin to clean everything after fitting the balancer with a new sleeve. Hey why not, I might as well try that since I have everything apart. I am cleaning the surfaces and I notice this piece of metal slightly larger than a silver dollar laying in the cross member below the crank????? What is this I think.

I pick it up and it looks like something has been rubbing and cutting through this piece of metal, the edges are jagged and it looks like there are stress fractures jetting outward from the center of the circle. It takes me about 10 second to realize what the piece of metal is from. "The Timing Cover". NO WAY, it can't be! I reach up under the water pump and sure enough a hole right through it! Directly in front of the freakin cam! What could it be. My first thought was one of the bolts worked loose and came in contact with the cover. I immediately started tearing the other items out of the car. I pulled the water pump and it became very apparent what the problem was.....The dowel pin on the cam was hitting the cover! I still did not know if something was allowing the cam to walk back and forth, thus allowing the pin to contact the cover. So I ripped the timing cover off. Everything was just as it should have been . The freakin pin on the cam is sticking out of the timing sprocket a good .5" I could not believe it. I thought that maybe the pin was not pressed in all the way so I tapped on it slightly. No way was that thing moving. Solid as a rock.

I was really ticked. I paid top dollar for the Lingenfelter 219 cam and this is the quality you get! Nonsence. I am going to have a few choise words for them tommorrow.

Now I am wondering if I even have the right cam. Is there any way to tell? Sorry getting off my point.

But it also dawned on me that this is why I was getting so much knock! Everytime I would hit the gas it would give knock counts and they seemed to not always follow the same pattern. Probably because sometimes it was hitting and others not.

Point of the whole story is one for me to vent and another to let you know that just when you think you have things straightened out, you realize the whole game changed.

Once again I will ask the question...how the hell would you have found that false knock?

What a night

funstick

im only asking this question to be quorious. if i had an engine that clearly did not exhibit detonation wouldn;t i be looking for a mechinaical reason ???? first of all a loose rod bearing can make a very faint rapping noise under moderate to heavy load ??? check the oil pressure, collapsped lifter ??? maybe a loose timing chain?????? why didn;t you check these things ???? maybe you had a bent pushrod that had to much lash ??? i geuss stethascopes have lost populatrity ??? not trying to be rude just wondering why the thought process never lead you to checking mechnaical things.

tpi_roc

Ski:

Thats terrible man Really chitty, at least you found it, I'm sure you'll have it right back together and just think of all taht extra timing you have to find out how your engine responds to now that you dont have that dowl pin in the way.

ski_dwn_it

Fun,

I spent A LOT of timing checking for the knock! As it turns out the setup has only about 400 miles on it as of now. So you would think the new timing set was OK. Now with that being said I never *heard* anything that was suspect. It must have been only hitting under heavy loads.

Who would have known? And to find the problem, you would have had to rip the whole front of the engine off, as I just did. Who is going to go to those kinds of lengths when I have tuned many older, and newer car that had no knock sensor.

My opinion of the knock sensors is they are great under ideal conditions, but when in many cases they drive you nuts. Now understand I realize the value of them and also they save a lot of peoples engines. Granted all is true and I am willing to deal with the consiquences.

Good Day!

tpi_roc

Ski

I know ligenfelter sells some extra long thrust buttons...


What year is your block, you have a roller cam right? Is there a thrust plate installed?

ski_dwn_it

Yeah mine is a roller. I just used the original hold in mechanism.......Did not use and aftermarket roller style. Called them and he said the extra long pin is for the *Opticrap* I should have pulled that pin and installed my existing one. Said he would just wack it off now.

Guess that is the only real choise I have now. Sure as heck am not going to pull the SR and manifold.

Knew I bought that dremel for something.

tpi_roc

Ahh lt1 cam


Doesn't that pin drive the water pump?

ski_dwn_it

Yeah on the later style vetts. Not on mine. We are a bit off the subject though. Sorry.

tpi_roc

Well my latest progress is such.

I started to push timing trying to nail it. I ended up one time getting half a tank of gas somewhere other than chevron and bingo, det at alot lower ° of advance. So anywho beyond that I pulled out all of my PE advance, Im trying to push knock at all rpm/load (very lightly) and then back it up 3°, I will then back it up another 1° or 2° (4°-5° total) and add the PE advance back in, that way the only time im even close to knock is if im WOT, and I still know I'm below the limits of my car then by a degree or two (On bad gas)

I think this sounds safe and makes sense, obviously If i advance timing and lose power at any given rpm/load i'll back up to where I made more and call that good.


But what do you guys think about this angle of attack?

ski_dwn_it

Your analysing again!

tpi_roc

Yup


I need to get myself to the point of a *good* timing curve so that I can work on it. Right now I'm sure im high in spots, and low in others.

Bobalos

As Grumpy said in one of his following posts, there are a LOT of ways of going about this. there are I think a couple of important issues here to note. first is that if you start with this method of tuning (which I subscribe to BTW), there are a few things to think about. first is that this is going to take a number of runs @ this & to have that in mind in the first place. if you have backed out some timing, & are going to adjust the VE to get your fuel you can dial it in all 128's, nuts on. then you can pull some timing in & you are likely to see that you are going lean (BLM's moving up), the question is do I put in more fuel or back the timing back down. I prescribe to putting in more fuel, if the engine "likes it" then you are good & you can try again (with more timing to see if you still need to go more).

the problem that I REALLY had was how do I gauge if the motor "likes" my changes. IOW, how do I know that my changes are for the good or am I just spewing gas out the pipe. the answer is, is the engine becoming more Volumetrically efficient or less (& I use VE in my own special way here, not in a strictly scientific application specific manner). to gauge that we need to have a ruler. the ruler for me was that if I have a constant load (65 MPH, down the SAME road) does it take more or less foot to get there? if it takes more then I have gone the wrong way, if it takes less, I am moving in a foward direction. IMO though this is way down the line from "starting off".

another thing to consider, is that when I first started out my tables were SO FAT that I had a TON of timing in & I still was not seeing any detonation. I asked a buddy to look @ my bin & he said that it had SOO much timing that he was VERY surprised that it was not detonating. the answer was that the fuel came in SO early & SOO much that it was not allowing the motor to get to that point. one little golden nugget is, it is MUCH easier to Prevent detonation with more fuel or less timing than it is to Stop detonation with more fuel & less timing.

One highly embarising situation on this same subject was that he kept saying "thats TOO much timing", so I said "fine" I will do a tuneup & check all the basics & start over. come to find out, I had the distrubutor turned back almost 8*, so the entire table was really 8* off from what I thought it really was. that was the difference from what he was thinking, which made a LOT of sense in that situation. that is to say, that even if you have been a "mechanic" for 20 years, everyone can make mistakes & the FIRST place to start is with the basics. Take 3 weeks of tuning & Throw them out the window right?.

BW

tpi_roc

Good call on a few points there.

Actually I'm quite surpised someone didn't beat you to the rich/lean vs spark relationships since I left myself wide open on it. However I was fully aware of that in the begining and have in cases found knock at loads and RPM that surprised me, looked at the 02 reading right next to it and bingo, lean spot, so yea I add more fuel and it goes away. I'm doing a balancing act as I'm going along but sometimes it seems so perfect, and just a 2° change in maybe 2 different cells on the timing table and wham my car feels like a dog.

Btw I dont know if you're using a '730 but In my scenerio this is currently a '165 so VE tables dont necissarily apply, however its still usefull as the only thing keeping me from running SD is completion of my LT1 intake, aquiring a remote coil distrib, and finding a '730 in a yard somewhere (surprisingly the hardest part)


Thanks

Bobalos

I am using the 7730/$8D setup on my SR. Mind you I have not even looked @ a MAF car, let alone tried to tune one, but Air is Air & Fuel is Fuel & they have to be right in order to "work" (to paraphrase Grumpy). so the principles still apply.

I am shocked that you are having a hard time finding ECM's. I went to Ludis page & found out all the motors/setups that have them & then went down the rows @ the yard & just looked @ the motors & there were more than I could throw a rock @. BUT (& I have a big Butt), they are ALL V6 ECM's. not that the ECM cares, but I have not found a single V8 one so that I can get the MemCal out of it.

Happy Promming!
BW

Jaysz28

iTrader: (30)

So what does your example spark curve look like above 4800 rpm????

By looking at your example, I'm way off in my spark table

thanks

1bad91Z

iTrader: (1)

Here's mine.

1bad91Z

iTrader: (1)

Oops, try this again!

11sORbust

20kpa area for deaccel? The timing in that column is considerably different...

anesthes

iTrader: (12)

I'm assuming from the small amount of total timing in the higher load areas (26d) and the fact that your using 85pph injectors (1050hp with a .55 BSFC @ 50psi and 80%dc) that this is a highly supercharged application?

My max timing from 3200 onward is 25d (with pe, btm, etc)
and I get a small hint of knock from lack of fuel I think..

Motor is 8.96:1 c/r, iron heads, 280/288 cam, and 8psi (720cfm) blower.

-- Joe

Low C1500

Those 85 pph injectors are on a tbi, so only 2 injectors total.

anesthes

iTrader: (12)

We're entitled to a retarded statement once and a while, arn't we??

I'm still curious about the timing though..

-- Joe

djdsails

What is knock??

RBob

iTrader: (1)

Detonation.

RBob.

djdsails

But isn't the engine always dentonating. What makes a knock different?
Does it happen when the engine is at low rpm and you try an accelerate quickly?

anesthes

iTrader: (12)

Perhaps you should start a new thread..?

-- Joe

34blazer

its like the second coming of jesus. holy crap. google will answer this question

Ronny

iTrader: (1)

http://en.wikipedia.org/wiki/Engine_knocking

google is my friend .....