1bad91Z

iTrader: (1)

Can someone explain how base timing is added or calculated in to the main spark table?

I have my base timing constant set to 6* in the .bin.

My mechanicle is set to 8* on distrib (it's runs better like that).

Datamaster shows 38* spark advance at WOT and in upper r's.

Does this mean that at WOT. I'm really running 40* timing beings my mechanicle timing is 2* higher than the base timing constant?

This is how I setup my main spark table and PE timing:

1bad91Z

iTrader: (1)

Here is the Extended table:

1bad91Z

iTrader: (1)

And finally, here is power enrichment spark. Anything you guys would change or dont like about it?

Comments, thoughts, suggestions?

TRAXION

Yes, it does mean that you are running 40d.

Tim

1bad91Z

iTrader: (1)

Is that too much?

Should I lower my timing in upper and extended to 34 that way it makes me run 36 total?

Are my tables too agressive?

Trax - is what I did something similar to your spark table setup?

What do you guys run total degrees at 4,000 on up?

Ed Maher

Every engine is diffierent, but 40' total timing off the top would be most at home in a low compression, big lazy cammed, 70s headed engine.


To directly answer the question, if you didn't arrive at your total of 40' of timing through TnT, then it could easily be too much. Better to start too low than too high. All timing in by 3200 is no big deal, could even be considered lazy if your converter doesn't stall higher than 3200.

The questions you ask cannot be answered in a general sense though. 'Too aggressive' and 'Too much' can only be guaged by whether it's slowing you down. Not what strangers in another part of the country think.

1bad91Z

iTrader: (1)

I have a six-speed in the car, so no stall, but I'm just curious to the way other people have their tables set like (with healthy cams).

Also, I still would like a better understanding on how all the timing tables add up.

Thats why I zero'd out PE spark and modded just the main spark table.

Grumpy

The trick is running the least amount of timing that supports max performance. And that takes lots of experimenting.

Too much timing, and too much fuel will just about always feel fast, but may not be in fact the fastest way down the track. You'll also notice the top ring lands either loose or busted out at dissassembly.

With 2d added to all your table entries, you get into the LOTS of timing category.

For a long lasting street motor I error on the side of running a lil less then optimum timing to gain engine life.

1bad91Z

iTrader: (1)

What are your thoughts on Zero'ing out PE spark and just up the timing in the main spark table?

Is there are magical number to run at WOT?

I've heard 36* total at WOT in upper rpm's is optimal.

Ed Maher

I've been running with the PE spark advance zero'd out for a while too. No problems even with an aggressive TCC at highway cruise and high TPS% enable. Admittedly i haven't driven the car much this year to actually test anything out, but it worked great for what i was doing.

No such thing as magical numbers. If somoene tells you something is 'the magic number' or 'optimal' then they are giving you outdated generalizations. TnT is the only way to go.

OMINOUS_87

Most folks with Vortec heads get away with WOT advance in the mid-low 30s: 32, 34, 36.

40* is a but load of WOT advance to start out with if you are just starting to try and nail down the WOT fuel and spark curves.

How did you cook up that table in the first place?

Grumpy

I've been running 0'd out PE spark for years.
There is nothing magical about tuning. It's finding what works best for your combo.

The 36d goes back for eons with the GM Power Book Series, and probably back to the flathead ford days.
The smaller the combustion chamer, and it hence it's surface area, means more heat gets kept in the chamber, and that means less timing. Add turbulent chambers, and even less.

I had a 9.5 CR L98 AL headed 355 that loved 26-28d.

rhuarc31

Grumpy is absolutely right, lots of the newer heads actually make more power at less timing. Year or two ago car craft did a build where they got the best power out of a vortec headed engine at 32*. Anything that affects the speed of mixture burn and detonation sensitivity will affect optimum timing. Somewhere betweeen 32 and 36 degree's is a usually a good place to start, but it's only a start, you'll have to test to see what gets you the best results.

JP84Z430HP

Just a question to try to help, where do you guys reccomend starting on the timing? 28? 30? Lower?

This is something that I know depands on application, etc....but I don't remmeber any mentioning where to start on some of these things! I do know that low timing, and more than enough fuel is the way to go, but does anyone have a base number they reccomend, or is that something that you suggest to get from experience?

Thanks for your input!

dimented24x7

iTrader: (2)

I cant really comment since my timing curves are set up for an engine that runs on diluted camel pee but 45 degrees of advance is the theoretical limit for a distributer given the spacing between the terminals in the cap. IIRC the ecm wont allow much more then 40 degrees of advance, anyhow.

1bad91Z

iTrader: (1)

If I just change my base timing constant in .bin from 6* to 8*, then will it minus 2* from the whole spark table?

TRAXION

No, it won't. The base timing table is a "WYSIWYG" (What you see is what you get). If you have 38 in that table then the ECM will advance the timing whatever is necessary PAST the base constant to achieve 38. So, if your base constant is 8 and your mechanical is 8 ... then the ECM will advance it 30d to achieve 38.

Tim

1bad91Z

iTrader: (1)

OH , ok! (light bulb turned on)...........

rhuarc31

I usually like to start at 32* and tune from there in an NA application.

TPIgirl

Just wondering since the distributor turns half speed of the crank wouldn't the spark advance limit be 90* ?

JP84Z430HP

Thanks rhuarc. That's the range I was figuring on usiong when I get going!

TPIgirl,
Once you get half way between the terminals (45*) it could start sending the spark to the adjacent terminal.

Low C1500

Just thought I'd add that my setup runs strongest at 28 deg total. I've had it as high as 36, but it was knocking bad.

TPIgirl

Thank you that makes sense. Before I narrowed my rotor tip it was wide enough to probably cover several degrees just by the width of the rotor tip.

1bad91Z

iTrader: (1)

Why would you want to narrow the rotor tip?


I think I'm also going to lower my timing in main spark by a couple of degrees before tuning VE.

Also, would raising PE TPS % threshold to higher setting's help VEMaster tune VE in more RPM's (to get more RPM VE tune without engaging PE)?

??

TRAXION

Absolutely. Just be careful. I like to progressively raise the %TPS needed to slowly dial in the upper VE tables.

Remember - VEMaster is only a tool. It's not foolproof and for me it seems less accurate in the upper RPMs.

Tim

1bad91Z

iTrader: (1)

What rpm's does VE go upto before entering PE?

And, what rpm limit in VE is VEMaster good for tuning upto?

1bad91Z

iTrader: (1)

ttt

1bad91Z

iTrader: (1)

What rpm's does VE go upto before entering PE?

And, what rpm limit in VE is VEMaster good for tuning upto?

Anyone?

Low C1500

PE is determined usually by tps %. Not sure on VE master, mayber 6400 rpm

1bad91Z

iTrader: (1)

So VE can go upto 6,400 rpms, as long as you dont go passed TPS threshold for PE?

Low C1500

DOn't get to concerned with VE stuff at that high of an rpm.