It appears that in order to have a good running engine with good power and no miss fires or backfires, the static timing is very advanced, on the order of 16 to 20 degress.

Its so far advanced that its well off the timing tab.

What is causeing this??????

When I run the engine at 6 to 8 degrees of static timing, the engine sutters and runs hot.

I have remove my timing cover and checked that the dots on the timing gear are properly lined up.

When I put the damoer back on the keyway with the #1 piston at Firing TCD, the timing line on the damper was right at 0 degrees on the timing tab.

I dont have a clue!!!!!!!!!

Does someone of an idea of this problem?

The car will run 13.25sec at a slow track with the static timing set at maybe 20 degrees, the total timing is about 32 degrees.

And yes I know to disconnect the ECM control wire to the distributor when I set static timng.

Can someone help me out???


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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 cam, 2400 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, 24#/hr SVO injectors, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB with airfoil, TB coolant bypass, AFPR(58psi), K&N filters, Hotchkis lowering springs, my custom chip, Lay Ind. ram air kit, SS Brakes 1LE upgrade 12" rotors dual piston calipers, 265/45R16 Kumho V700 tires.
ET 13.39sec @ 107.21mph
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow airlid, K&N filter, next mod: 4.10 rear gears
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph

 

Doc, do you have a modified eprom in your car? If so, someone may have changed the "Base Timing" constant on your car.

On MAF cars, the "Base Timing" is part of the Spark Advance to produce a "relative timing" that is the amount of spark added over the base. If someone changed the Base Timing to 20*, and your Total Timing is suppose to be 42* at a specific RPM/Load, the ECM will add 22* to the "relative timing" to give you a total timing of 42*.

Conversely, if the Base Timing is only 6*, the ECm will add 36* "relative timing" to give you your 42* timing. You Base Timing must be in "sync" with your actual distributor timing.

PS: Do you have any SES codes? They can cause you to go to "Fail Safe" defaults. Also, MAF cars do not have a "Normal Mode" for scanning. As I understand it, the "ALDL Mode" actually overrides some values. This may be different for MAF, but for SD cars, we MUST use "Normal Mode" to ensure the scan tool does not override any of the settings.

 

I have no SES codes.

Also, I burn my own Eproms based on the "custom" CarPro chip I got about 2 to 3 years ago.

I have not changed anything dealing with timing. I have only changed the constant value for the fuel injectors and the tables for WOT.

I will check the timing table that I am currently using.

I updated my profile since the first post.

It also seems that I need to run very low fuel pressure since I swapped in 24#/hr SVO injectors. I dont like this. I'm thinking that I should install real 24#/hr GM injectors and then run higher fuel pressure.
With 22#/hr injectors and maxed out at 58psi, the engine needed maybe 5 to 10% more fuel at WOT.

Glenn, you responded to some of my questions over on the PROM board. I appreciate your help very much, thanks.

I'm going to get on a chassis dyno soon to check out my fuel pressure situation.

Maybe I should dyno different base timing values when I'm on the dyno.



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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 cam, 3000 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, 24#/hr SVO injectors, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB with airfoil, TB coolant bypass, AFPR(40psi), K&N filters, Hotchkis lowering springs, my custom chip, Lay Ind. ram air kit, SS Brakes 1LE upgrade 12" rotors dual piston calipers, 265/45R16 Kumho V700 tires.
ET 13.27sec @ 103mph on MT ET Streets
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow airlid, K&N filter, next mod: 4.10 rear gears
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph