First off I ran a new best time of 11.66@117.2mph that you can read about HERE.

Instead of starting off the spark advance low and building it up ... my entire 100kPa region starts at 38d at the low 400rpm setting. There's no gradual increase in SA. I pop immediately to my max setting and then taper off to 36 and then to 34 after peak torque. I was rewarded with 1.62 short times ... on Drag Radials. This is with the stock IROC-Z springs and shocks. The swaybars were also installed. I was basically in street trim except for a set of front skinnies. Even my rear rims were stock IROC rims except for the DRs. Not too bad for a naturally aspirated stock GM 350 motor with a never rebuilt 700R4. Of paticular note is the fact that I am running a 3600 stall vigilante and it WAS stalling at 3600. I am thinking that the immediate spark advance really helped spool the converter up quickly.

Tim

 

Very nice Tim. Glad to hear you got the car back where you want it and have it out racing......

now based on what you posted, is it safe to assume you disabled PE? Or does PE operate strictly off the variables in the VE tables at 100 kpa?

If I'm way off base, don't bother correcting me. I'll just edit my post to try and save some face. LOL

I'm still getting my butt kicked by my Tq arm, so I'm not too worried about tuning at the moment

 

Waaaasssuuuuuuuup Jason!

No no. PE is still fully enabled. All I am talking about is the 95 and 100kPa columns in the main and extended spark advance table. If you look at that 3D table the RPMs start at 400rpms. Well - at 400rpms at 95 and 100kPa I have 38d of spark advance. I then have 38d going all the way down the 95 and 100kPa columns ... until after peak torque where I drop to 36d and then finally 34d.

Points of note:
1) I don't use the PE Spark Advance table. I have all my spark advance in the Main and Extended tables.
2) I always set the 95 and 100kPa columns the same. This is because my motor pulls a slight vacuum at WOT where the kPa drops to 96.

Tim

 

sounds alot like how I tun WOT s/a

 

That looks nothing like what I am talking about.

Tim

 

Here is what I mean ...

Tim

 

Thanks TRAX.

I am just getting around to doing serious tunning on my spark tables. That table sounds alot like the preliminary table that I came up with to use untill I get my fuel a little bit closer . Maybe I am closer than I think on my spark, I have not had any issues with timing but maybe there is a little torque or HP left to ring out of it.


ED

 

Nice Job Tim,
Nice to see you finally Update your track results - Alot of peeps have been waiting to see those.
Very Nice Times - my suspension is same as yours, All I have done is Boxed them and Poly bushings.
Though I was thinking of double nutting them for more free movement.
Again Excellent times,Nice MPH,and short times.

 

Well that makes sense then

I haven't begun to play with my spark tables yet

but I have to ask, how do I disable the PE spark tables? PE is the only time I have knock counts and knock retard and its driving me nuts as none of my changes seem to fix it..........

 

How's your initial startup? Only reason I ask is that during startup aren't you at 95-100kpa around 400rpm? Or do you have a cranking sa table in your code?

 

Great Job Tim.
So how is that new cam overall

I set my timing map close to yours. I do add about 3 degrees in PE mode though.
One note. Why are you getting some vacum at WOT.
I do also. Mine is due to I still have my maf and its ducting. If I remove this ducting and run down the track I stay right at 99KPA. My 85 ducting is limiting my setup. This happens from about 6200-7000rpm.
Another case is Hoover (LT403). His vacum use to fall to 90KPA under WOT. He installed a 1300 CFM monoblade and the ram air ducting on his vette.(he shifts at 7200)
I still would argue some piont that the L98 maf will limit airflow on big cubes and HIgh RPMs.

Dennis

 

Jason,

There's no easy way for you to go in and just disable PE spark. However, you CAN just set all the PE spark to 0 like I did. The small 2D table in the pic above is the PE Spark adder. I have mine zeroed out. I want to note that I did this for simplicity only. I am in no way saying that this is the best thing to do. I have all my PE spark in the 95 and 100kPa columns because I will always be at those MAP values when in PE ... thus, this just makes tuning WOT easier for me since I never have to worry about back-calculating the real SA by considering the PE SA adder table. Rather, I just look at the main spark advance table and see the full picture. Again - I'm not saying this is the best thing to do ... it's just what I do for simplicity.

Tim

 

My initial startup is great. Turn the key - it starts up. No problems whatsoever.

In terms of the specifics regarding the spark at startup, I haven't explored the AUJP code to research what EXACTLY is done on startup in terms of what tables are followed, etc. I am assuming that you mean while cranking right? And not after it is actually fired? Two different things because after it is actually fired my idle is at 75kPa @ 900rpms so those columns don't matter.

This is one of those cases where an ECM Bench is worth it's weight in gold. I don't NEED to know the answer to your question because my car starts fine. However, it is a good question and an ECM bench could reveal the answer fairly quickly.

Tim

 

Dennis,

One thing is for sure - it's not my airbox. I removed that for testing and the same thing happens. It's either the 58mm TB, the MiniRam 1204 ports, or the heads. I don't think it's the heads It's either the 1204 ports or the 58mm TB. Just not sure which one because I don't think either should be causing it. I wish I knew somebody with a monoblade just so I could test it.

Tim

 

During crank the timing is run from the distributor. It fires at the DRP pulse which will be the inital timing setting (just the same as the EST line manually opened). As the engine catches and starts to run the timing is advanced to the run point of the closed throttle table. The change over from crank to run is a blend, it is done smoothly.

RBob.

 

I ment the general idea of bringing the total in faster....

 

Tim,
That is exactly the answer I was looking for. So to cancel the PE spark, just zero out the PE spark table, I can see where that would make tuning a lot simpler to say the least. Anything to make tuning simpler is a good thing IMHO

Thanks and again, congrats on the new best

 

why 0 out the pe timing adder?

 

Just one question on restrictions in the intake tract. If the map sensor is reading manifold vacuum or the lack there of, and is connected to the plenum area of the manifold, how would it see a restriction below it in the intake runners or the heads?

Steve

 

because ...

 

Steve,

I think you may have just stated the obvious for me. THANKS! I am going to try a new MAP sensor (which I don't think will work) ... then I need to find somebody with a monoblade TB. It would be really really funny if my 58mm TB was a restriction on my 'lil 350. That would put all those theories and calculations on necessary TB size to rest. Thanks again!

Tim

 

Thanks RBob. That's very informative.

Tim

 

I thought you had a reason for doing that. I was thinking about doing the same thing. But don't know why it's better/different than using the pe timing table.

Tim

 

Yea, for me it's just simpler. I really like the fact that GM gives you the option to put it into a different table. I just don't NEED that option. I am never at 95 or 100kPa unless I am in PE so there is no need for me to have different values for PE vs. non-PE. Thus, to look at just my spark table and see the whole story is very nice.

Tim

 

huh im glad youve seen the rise in cylinder pressure with spark advance id been following for quite some time. i was hinting at this about this time last year but was smacked down. anyways glad to see it paid off. and congrat on the time. !!!!!

 

Funstick,

I've known about it for a long time. I just haven't been to the track in over 2 years

Tim

 

I posted a data log some time ago that showed the first start, and pumping down of the intake manifold.
With what you have your going from whatever you base timing is to 38d at 400 RPM or so, as the EST takes command of things. Plus whatever the coolant temp offset is, so your probably running on the max time allowed parameter.

While it might feel fine, you're also at the point where oil is first circulating, and the clearances are at their worst. And probably at 42d timing at 500 RPM. Not to mention it's still burning off the crank prime. So you have full advance, real rich, loose clearnaces, and low rpm. Just something to think about.

 

So, which one is correct? Bruce, you are saying that I am going from 10d to 38d. RBob is saying I am going from 10d to the value in my closed throttle SA table.

Tim

 

Ahh, I misplaced the grey cell with that you had that.

 

I don't understand this sentence.

Tim

 

I'm glad someone else spoke up !
I thought that I had been reading to much.
I'll bet that there is something to be learned from that sentence.

 

Here's what I am getting out of things regarding startup SA.

1) It operates exactly as RBob pointed out. Cranking uses the default distributor timing and then when it is fired it operates off the closed throttle SA table.
2) Once fired there are adders and/or subtractors to this closed throttle table; namely, the "Startup Spark Advance vs. Coolant" as well as the "Base cool advance correction vs. Load vs. RPM".

Using an AUJP BIN the overall startup spark advance immediately after firing the engine with a coolant temp of 20d C, a 600RPM idle, and a 40kPa idle load would yield 29d of advance. I'll check this on my car as soon as I get a chance.

Tim

 

Quick ? for you Trax...........

Since you have your mech. base at 10*, does this mean that you are running 34.1* at 100 kPa @ 5,600 rpm's, or are you really at 38.1 due to 4 degree's more advance on mech. base?

 

It means that I am at 34.1d. See my reply to your other post. Unlike you - I DO HAVE my base timing constant in the PROM at a setting that MATCHes my true mechanical timing. Both are at 10d.

Tim