If 10 degrees BTDC is standard timing, what is advance?

[Rick's Fords]

I've read of some people using 12 deg and some using 14.

We installed a 70 MM TB today, and it's running good. There's also the CAI and open exhaust beyond cats to keep in mind.

And I am also removing that mechanical fan today!

 

[srothfuss]

The EEC automatically adjusts the timing with the car running based on different loads and driving conditions to get the programed power out of the car based on 10 degrees. The base timing is set at 10 degrees. When you advance your timing, you get some free power at the cost of running higher octane (in typical cases)

Around 12 degrees you might not need to run higher octane, but at 14 you will need the better fuel.

Probably not the best explaination, but I hope it helps!

 

[HISSIN50]

No two set-ups are the same. You will have to try it and see what works for you. Most folks fall between 10-15* advance. If you have to up the octane, back the timing down a little.

Good luck.

 

[Rick's Fords]

Thanks for the replies guys. Now I line the 10 BTDC mark on the crank with the pointer mounted to the block, make sure it's on compression stroke (screwdriver in spark plug hole, and piston almost topped out), and them make sure the rotor button points to plug wire #1, right?

 

[slow5poh]

I don't mean to hijack this thread but i got a related question. When i bumped my timing on my stock 5.0 about 2yrs ago, i did it at work. I work at a chevy dealer. This old school mechanic that works here told me that since i was only changing my base timing from 10deg to 14deg, that i wasn't accomplishing anything. His reasoning was that since the computer will change the timing when the SPOUT was plugged in, that changing the base timing is pointless. He is a good tech, but i know he is wrong about this, how do i explain to him that he is wrong and why?

 

[nosmatt]

he is wrong becuase, as was already correctly pointed out above, the computer adjusts timing BASED on the factory setting of 10*.

check your timing with the spout in, start car cold.......see where your at.
remove the spout, it will only drop to where you set it, and the computer adjusts based on load, air charge temp, coolant temp, throttle position, and mass air flow (for 88 cali, and 89-95 5.0's anyway).

 

[slow5poh]

thanx matt.

 

[HISSIN50]

Slow5poh, was the mechanic aware that we dont have piezo sensors? Those are common on later GM's so that might have been what he was thinking about. If so, in a sense he was right.

 

[JJFIVEOH]

So technically speaking, how much can you possibly advance timing? I run 20 degrees initial on mine, using VP Motorsport103 fuel. It is a stock motor used only as a bracket car. I've tried many timing settings and this is where it runs best. People say never go higher than 16, but this has worked for years and just wondering what your opinions are on this?

 

[troyGT03]

you can adjust timing until detonation(pinging) occurs and then back off. the reason you can run 20 degrees is because of the race gas. the higher the octane the slower the fuel/air mixture burns. from your mod list with nothing but exhaust and rockers.... 103 octane with 20 degree timing would be about the same as using 93 octane with 13-14 degree timing. whatever makes you feel better. timing vs horsepower does fall after a point even without noticeable detonation. i have seen this on many engines on the dyno. i used to build racing engines professionally. there is a "sweet spot" on any engine. also are you still running with the spout connector in the distributor harness?

 

[JJFIVEOH]

I am still running with the spout connector installed. I guess that is what I was trying to get at. If there is no detonation, why and when does the computer start to make it's own adjustments? I use the 20 degrees and VP 103 because the car never sees the street, it's more responsive off the line and less susceptible to air changes. I need the quick response for reaction times, and with the crappy tropical air here in FL, it makes it much easier to dial in with the VP 103. I've been running like this for a while, but I want to try running without the spout connector and lock the timing down so the computer has less control.

 

[troyGT03]

I am still running with the spout connector installed. I guess that is what I was trying to get at. If there is no detonation, why and when does the computer start to make it's own adjustments? I use the 20 degrees and VP 103 because the car never sees the street, it's more responsive off the line and less susceptible to air changes. I need the quick response for reaction times, and with the crappy tropical air here in FL, it makes it much easier to dial in with the VP 103. I've been running like this for a while, but I want to try running without the spout connector and lock the timing down so the computer has less control.

you sound like you have a good stand on your car. "sweet spot". if it works it works. as for doing the old school locking the timing down issue- it has been tried. the car will blow the tires on the bottom end but will fall off on the top end. do a search i may be wrong. lots of timing calls for a higher octane(slower burning) fuel. and vp is a better burning fuel than pump gas.as for when the ecu decides to adjust timing... it looks at thottle(tps) , o2, coolant temp and mass air or map to decide on wheather to adjust the timing factor. like i said it is what each engine likes. is your setup where the car runs the fastest times?

 

[HISSIN50]

I am still running with the spout connector installed. I guess that is what I was trying to get at. If there is no detonation, why and when does the computer start to make it's own adjustments? I use the 20 degrees and VP 103 because the car never sees the street, it's more responsive off the line and less susceptible to air changes. I need the quick response for reaction times, and with the crappy tropical air here in FL, it makes it much easier to dial in with the VP 103. I've been running like this for a while, but I want to try running without the spout connector and lock the timing down so the computer has less control.

The computer's advance tables are set. All you do when advancing the timing is to phase-shift the tabling. Like if you ran 10* base timing (SPOUT out) and put the SPOUT back in, timing goes to ~20*. Now in some given situation, let's say your timing is 40* total.
If you bump static timing to 14* instead of 10, now with the SPOUT reinstalled, you will see around 24* (instead of 20*). And in that same random situation as above, you would see 44* total timing rather than 40. It is just a phase shift.

 

[JJFIVEOH]

It's setup to run the quickest, but still have all the accessories to make pass after pass. i.e. no icing intake, full belt to cool and charge, etc. It was dynoed with peak HP at 4950. So even if I retarded it to get some top end, the motor can't breath for it to make any difference. With 26" tires and 4.10 gears, I go through around 5200. Bracket racing season down here runs from January till October so I have a little time to mess around. The car is deadly consistent, but I'd say on average once out of every 20 runs it throws a curveball at me. I know even carbed drag cars do the same thing, but I figure if I can take away as much computer control as I can, I can eliminate those "freak" runs. I was just wondering about computer control with the spout connector pluged in.

 

[87gtconv]

My street Stang works best at about 14* without spout on Calif 91 octane gas. I get summer pinging (above about 90*) at anything above 14* and I am too lazy to have a summer and winter tune. At 10* it feels down right slugish!!

 

[troyGT03]

The computer's advance tables are set. All you do when advancing the timing is to phase-shift the tabling. Like if you ran 10* base timing (SPOUT out) and put the SPOUT back in, timing goes to ~20*. Now in some given situation, let's say your timing is 40* total.
If you bump static timing to 14* instead of 10, now with the SPOUT reinstalled, you will see around 24* (instead of 20*). And in that same random situation as above, you would see 44* total timing rather than 40. It is just a phase shift.

but the ecu still tries to adjust fuel/air mixture based on a 10 degree timing factor(facory setting was actually 7-9) while getting input from the sensors. i understand the programmed tables. i was gm certified in fuel injection but never ford.

 

[troyGT03]

It's setup to run the quickest, but still have all the accessories to make pass after pass. i.e. no icing intake, full belt to cool and charge, etc. It was dynoed with peak HP at 4950. So even if I retarded it to get some top end, the motor can't breath for it to make any difference. With 26" tires and 4.10 gears, I go through around 5200. Bracket racing season down here runs from January till October so I have a little time to mess around. The car is deadly consistent, but I'd say on average once out of every 20 runs it throws a curveball at me. I know even carbed drag cars do the same thing, but I figure if I can take away as much computer control as I can, I can eliminate those "freak" runs. I was just wondering about computer control with the spout connector pluged in.

this is a total drag car? probably never sees closed loop mode where all of the sensors come into play.

 

[JJFIVEOH]

but the ecu still tries to adjust fuel/air mixture based on a 10 degree timing factor(facory setting was actually 7-9) while getting input from the sensors. i understand the programmed tables. i was gm certified in fuel injection but never ford.

Not sure about the validity of this, but a couple of guys I bracket race with do not even use O2 sensors. Their cars are pretty consistent, although neither of them are street worthy. If it means anything, with 20 degrees initial timing, when I had mine dynoed it was putting out between 11.9-12.1 air/fule ratio.

 

[JJFIVEOH]

this is a total drag car? probably never sees closed loop mode where all of the sensors come into play.

If you are implying that it takes some time for all the sensors to come into play, my fluke runs usually happen after I've made several runs. After a fluke run, it'll continue to run that way the rest of the night. So I guess what you are thinking would make sense.

 

[troyGT03]

If you are implying that it takes some time for all the sensors to come into play, my fluke runs usually happen after I've made several runs. After a fluke run, it'll continue to run that way the rest of the night. So I guess what you are thinking would make sense.

the open loop mode only uses certain sensors such as tps,etc. when a certain temp is achieved the closed loop begins and all sensor inputs are used to tune air/fuel mixture.