TBI timing advance for max power.

[TylerZ281500]

if your a tooth off in the dist or timing chain then 0 could be funky, gotta play it by ear and driving feel

 

[SkyHighColorado]

I just did 3* and it seems about right. I did mark the distributor in many places but I don't doubt I could be a tooth off!

 

[someotherguy]

Also be really, really sure you're doing this on a fully warmed up engine. There's a default timing curve built into the module; it will advance timing slightly as the engine speed increases, even with the bypass wire disconnected. It's nowhere near as aggressive as the normal timing curve while the wire is connected, but it's there. You want the engine hot so you're at normal idle speed while setting the base timing.

Again if you want to be positive you're set at the sweet spot, borrow a graphing scanner and watch for knock counts and knock retard. If you see very much of any, you have too much advance for your engine. The exact amount will vary based on wear, other factors like EGR performance, quality of fuel, amount of carbon buildup in the combustion chamber, cooling system efficiency, yada yada yada.

Richard

 

[SkyHighColorado]

Also be really, really sure you're doing this on a fully warmed up engine. There's a default timing curve built into the module; it will advance timing slightly as the engine speed increases, even with the bypass wire disconnected. It's nowhere near as aggressive as the normal timing curve while the wire is connected, but it's there. You want the engine hot so you're at normal idle speed while setting the base timing.

Again if you want to be positive you're set at the sweet spot, borrow a graphing scanner and watch for knock counts and knock retard. If you see very much of any, you have too much advance for your engine. The exact amount will vary based on wear, other factors like EGR performance, quality of fuel, amount of carbon buildup in the combustion chamber, cooling system efficiency, yada yada yada.

Richard

I just ordered an OBD usb cable yesterday, I plan on using ALDLwin or something along those lines. What do you use? I have it fully warmed up when I do the timing I drive for about 20 mins or so then do it.

So how much knock count would be acceptable, I get the impression from what you said ill be seeing one or two.

 

[someotherguy]

I haven't tried any of the PC-based stuff. When I was chasing a serious driveability issue on a Vortec 7.4 I had borrowed an OTC Genesys (not cheap) from a good friend, handled the 7.4 issue (by the way if you unplug either of the dual knock sensors on a Vortec 7.4 it assumes "worst case scenario" and knock counts are through the roof, sort of a "save the engine" mode - freaky to see knock counts with both sensors disconnected!)...

...then used it to double-check what someone else was claiming about effects from even minor advances to base timing, and found he was right. I don't know what the threshold is for knock retard to occur, but it didn't seem like it took much. Also this was over 3 years ago so my memory is fuzzy on it, but I do remember at only 2° advance in base timing, I was getting enough knock counts on 87 octane to see knock retard happening. Can't remember how many degrees it was pulling out but any is enough to be counterproductive. I set back to zero and the knock counts dropped off dramatically. You'll still see a small amount of them under normal conditions, but not enough to ever be a problem.

Richard