Is too much timing bad?

Highbredcloud

Active Member
Mar 4, 2003
1,075
1
36
Palos Hills, IL
I'm running 20* timing with 48psi of fuel with vacuum off out of 30lb injectors...cars feels like crap...WTF...is it too much fuel or too much timing? Help me set the car where it is suppose to be at...I know that the stock fuel pressure should be around 39-40psi...however, it seems as if I set the fuel pressure at stock the car looses top end...at least it feels like it does...where should my timing be IF I run the stock fuel pressure? :shrug:

GT-40 X heads
GT-40 intake
FTI cam...along the rest of the bolt ons on a stock bottom 302
3.73's with a 5 speed...HELP anyone :shrug:
 
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Base timing of 20 is pretty high and is going to cause your eec advance to go way over MBT or Maximum Brake Torque spark.. This will cause you to loose power under load. I would recomend backing it down to the 4deg over stock that every one runs..
 
I'm with drgn - those heads/cam will want more than stock timing. 16-18 and stock fuel pressure. Disconnect the battery for a while to clear out the computer, and let the computer re-learn with stock pressure and the new timing.

Think of timing this way - the spark plug fires as the piston is coming up. As you keep advancing the timing, you're firing the plug earlier and earlier as the piston is compressing the charge. It needs to be fired before the piston is at the top in order to give the charge time to burn as rpms increase. But there comes a point where if you set it off too early while the piston's headed up, pressures/temps get so high in the chamber that detonation occurs. No good.
 
thanks guys...I set timing at 16* and 39 psi fuel pressure...car ran like crap at top end such as 3 and 4th gear...Than I set the timing back to 18* and 40 psi and the car runs much better...I did not reset the computer since as far as I know the computer is a learning computer and should re-learn the new settings right? Also could a TPS that is out of position make the car run like crap? I was thinking the MAF was the problems and was thinking about disconecting it and running the car with the MAF unplugged...any ideas if that is good or bad? I know my car is not running to it's full potential...and it is something dumb that is causing the car to run like crap...any thing that is obvious that I should look into? any selenoids or moduels that I need or may need to be replaced or cleaned...? I already checked my MAF sensor and it is clean...thanks guys...
 
Highbredcloud said:
yeah...after countless tries and assistance from Ed I just said F that and installed it straight up...the car made 291RWHP and 322RWTQ untuned...that's not where the problem lies...

I am running 93 octane at all times...

sorry, i was asking pny pwr. what mass air are you using?
 
Many, many drivability issues are caused by maf calibrations. What type are you using? Did you buy it new?

For what it's worth mine with typical bolt ons (H/C/I/Exh) runs 18 initial, 34 total timing at w.o.t. with regular 87 octane fuel - no detonation at all, even in the heat of summer.
 
question about my timing

I have a 1990 Gt pretty much stock except for intake coil and filter. I can only set my timing to 5 anything above that and the starter drags and the car will not turn over. You think my distributer is trashed or did my timing chain slip.
 
Michael Yount said:
Many, many drivability issues are caused by maf calibrations. What type are you using? Did you buy it new?

For what it's worth mine with typical bolt ons (H/C/I/Exh) runs 18 initial, 34 total timing at w.o.t. with regular 87 octane fuel - no detonation at all, even in the heat of summer.

I have a pro-M 77mm purchased it new and it is calibrated for 30# injectors...at least that's what I paid for...something just isn't right...thanks anyways guys...
 
Chris65 - did you pull the spout out before trying to set it?

Highbred - beyond injector size, was it set up for your inlet configuration - cold air, or stock box, and also for the exact computer that's in your car, etc.? There's more to the calibration than just the injector size. If you have the data sheet that came with it, the ideal situation is to use a chip/tweecer to input the voltage/flow curve from the maf data sheet into the computer. The ecu expects a certain match between the voltage signal and the actual flow - the stock maf matches the computer's expectations. Sometimes, that match gets out of whack with aftermarket maf's. The only way to fix that is to change the transfer function in the ecu. One thing you can do is to borrow a stock maf (for your year computer) and 19# injectors and see how it runs. That may tell you if it's an maf calibration issue.