"best ignition timing setting?"

[sxyvet]

hi there guys,

just wandering if you could please reccomend "best ignition timing setting" for 1991 l98 engine?

also "where is the plug/wire located exactly" to disconnect "ecm"/comptuer so that i can readjust setting/ignition timing with out computer setting it back to the old timing?

what color is this wire also please?

any particular step bye step procedure to set ignition timing you can please give me also?

thanks so much!
you are all so helpful.
thanks
glen
sxyvet
Australia

 

[speedmaster4]

"set timing" wire is tan/black stripe...black plasticconnector at left rear of engine...look below wiper motor

engine off ..rotate engine by 'bumping' starter until groove on harmonic balancer comes near 'timing tab' (below water pump-left side) ...apply dab of white paint to balancer groove and line on tab above '0' with 8 next to it

loosen distributor hold-down bolt with 9/16 wrench only enough so you can turn the distributor with some effort---there is an 'offset' disrtibutor wrench made just for purpose--get one or make one from an old 9/16 box end

attach timing lite to cyl 1 plug wire---do not use timing lites with 'spark adjust' built into timing lite ( most are off several degrees)...start engine,aim timing lite at timing tab,rotate distributor until white marks (see above) line up...turn engine off , tighten distrib hold-down bolt,restart engine and verify timing setting...stop engine, remove timing lite,reconnect "set timing connector", disconnect battery ground (- terminal) for 2 minutes to clear code set by running engine with "set timing conn" unplugged

 

[Edmond]

Glen,

I think the wire is brown, but I can't be too sure because I did it 1.5 years ago. You will need one of them weird looking wrenches to get to the nut that keeps the distributor tight. I think it's a 3/8" but my memory isn't that good.

I think I had mine set at 6*

 

[sxyvet]

hi speedmaster4 and edmond,
wow, thanks guys for the great write up!
you have helped me so much,its great mate!
thanks also to edmond too for your advice!

so should i set the timing at 6 degrees or 8 degress?

is the spanner a 9/16" or 3/8" that i need?

ecklers sells a distributor wrench that is a 12 point,9/16" for $9.99 on page 177 of there catologue which idid order a couple of weeks ago!
i hope that it fits!
cheers
glen
sxyvet
Australia

 

[speedmaster4]

the dist bolt is 3/8-16 thread with a 9/16 head

6 degrees is good
8 degrees usually a tiny gooder
10 pushing it but 93 octane usually cuts it

your engine has a 'knock sensor' that tells the ecm to retard spark before any damage is emminent...if you hear pinging ( 'tinny' rattling from engine,especially under light-medium load) - retard initial spark setting...if under hard acceleration the engine seems to 'surge' in power output- thats the ecm/knock sensor hearing ping that you cant hear-retard initial spark timing

 

[sxyvet]

the dist bolt is 3/8-16 thread with a 9/16 head

6 degrees is good
8 degrees usually a tiny gooder
10 pushing it but 93 octane usually cuts it

your engine has a 'knock sensor' that tells the ecm to retard spark before any damage is emminent...if you hear pinging ( 'tinny' rattling from engine,especially under light-medium load) - retard initial spark setting...if under hard acceleration the engine seems to 'surge' in power output- thats the ecm/knock sensor hearing ping that you cant hear-retard initial spark timing

hi again speedmaster4,
i run 98 high octane daily!
so there fore can i increase timing to 10 degress?
and those figures are they before or after tdc(top dead centre)?
thanks again
glen
sxyvet

 

[speedmaster4]

all timing numbers before top dead center ( 0 on timing tab )

some guys have run as much as 14* btdc initial....ideal way to find best is to take it to drag strip and keep advancing until no improvement is noted and then drop back a couple degrees....seat-of-pants feeling of power surge due to ecm/knock sensor retarding spark, and pinging sound of detonation (turn off the jukebox) are important to prevent engine meltdown

 

[sxyvet]

all timing numbers before top dead center ( 0 on timing tab )

some guys have run as much as 14* btdc initial....ideal way to find best is to take it to drag strip and keep advancing until no improvement is noted and then drop back a couple degrees....seat-of-pants feeling of power surge due to ecm/knock sensor retarding spark, and pinging sound of detonation (turn off the jukebox) are important to prevent engine meltdown

hi speedmaster4,
i just thought i would let you know how i went finally with the timing!
i followed your great,helpful instructions, thank you!
first i marked the harmonic balancer timing mark white like you said!
found the single black/brown stripe wire with plug near wiper motor!
disconnected it,put timing light clip on number one lead,fitted the positve& negative clips loosedned the single
9/16" bolt!
statred her up and it was showing 4 degrees before top dead centre!
quite low i thought!
but also i knoticed as i was loosening the distributor bolt i twas slightly loose so may be the distrubutor came loose and the timing went back to 4 degrees!
any way i set it on 10 degrees btdc as i always run 98 high grade octane fuel to cope with it!
the performace seems to be more smoother i guess what i found after i set it at 10 btdc!
once i had her set, turned it off,disconnected the negative terminal on battery for two minutes and wam, all done!
thanks so much for your help and advice mate!
really appreciate it very much!
cheers
glen
sxyvet
Australia

 

[MBDiagMan]

speedmaster,

I hope I'm not raining on your parade, but you need to check something before setting your timing to 10 BTDC.

There are two octane test methods. There is the motor method and the RON method (please don't ask me what RON stands for.) It could very well be that down under you use a different octane test method than we do here in the US, which MIGHT mean that you don't really have fuel with octane higher than what we have here.

I hope that I'm wrong, because if I am wrong, then you indeed have the good stuff down there.

Happy New Year and G'day,

 

[sxyvet]

hi there mbdiagman.
thanks for the reply!
our standard fuel is 91 octane, then preuium is 95/96 and then there is shell opti max=98,mobil synergy=98 octane,caltex zoom=also 98 octane!
this 98 fuel is 5-6 cents more than the other fuels!
thanks for the concern, i shall look in to what you have said about ratings!
cheers
glen
sxyvet
Australia

 

[speedmaster4]

yep-mbdiaman is on it-we here up/over (opposite of down/under)are told that our fuel is checked two ways--motor octane and research octane number -- then the two are "averaged"...sounds like smoke and mirrors to me...wouldn't surprise me if you blokes have a different (more honest) system

in the good ole days, we had 100 octane at the pump but honestly that stuff was loaded with tetraetyhl-lead (serious poison)..'racing gas' of 100+ octane is sold here, hughe cost and not legally road useable...if your stuff is top shelf via some other magic it would be of interest

back to thread-- distributor sits on gasket,bolt 'clamps' things down-not a really positive lock...there is "magnetic" drag in retard direction due to distributor internals--movement is not unusual--check occasionally

 

[ben73]

There are 3 ways to measure octane. RON, MON and PON.

In Australia, the octane numbers are RON (research octane number).
The guys in the US are quoting PON (pump) numbers, which is an average of the RON and MON (motor).
Our 98 is Australia is equivalent to about 93 in the US.
I make the stuff.

As for 'the best timing setting', each car is a bit different, and the only way is by testing.

 

[sxyvet]

hi ben73,
how are you!
thanks for your imput and info!
so if i run 98 octane @ 10 degrees btdc then they should be ok?
what state are you from any way ben if you dont mind me asking?
thanks
glen
sxyvet
dandenong, victoria-Australia

 

[ben73]

Hi Glen,
I am in Bris.
Some cars will be ok at 10deg btdc, others will ping.
Its just a matter of trial and error, but start at the factory recommended 6degs and go from there.
Ben.