Timing a stock GT

[MrPerfect2]

My 91 idles a bit choppy but drives good and has no ping on wot - i have owned it for a year and daily drive often . I use 87 gas . I noticed a mark scratched at base of distributor and another mark scratched on the manifold area - I am guessing this is a reference point on where the other owner set the timing . The damper marker is dirty so I would have to clean that off to read dashes . I do not have a timing light either . My engine runs hot in summer heat ( could be many things , but I made sure flow thru rad is good , coolant circulates strong , and fan , clutch and shrowd work good ) this summer I plan to run only water and maybe a wetting agent with corrosion protection . My question is if I pull spout connector off and loosen the bolt and rotate distributor ccw - how much do you actually move it to drop 2 degrees - is it about a 1/4” ? I figure i could always go back to original scratch marks where it was. I know the proper way would be to mark the damper with time light process , but ultimately I will be turning the distributor anyway and I am curious how much do you turn it to get a small change ?

 

[Potomus Pete]

Harbor Freight @ $22.00 . Mark it. Read about it, and go..

 

[MrPerfect2]

Yes , I know where to get one - that was not the question , it was how much do you move the distributor to change 2 degrees ? 1/8” , 1/4” , 1/2” ?

 

[Blown88GT]

Distributor doesn't move by inches but you can convert angular distance to radians.
You do the math.

Radians

 

[Potomus Pete]

I tried the no light method. Got it by sound. Idled ok but did not go higher rpms well enough.

 

[MrPerfect2]

I see your point on does not move in inches - let me better describe - approx how much of a turn do you rotate it - if it’s a clock about how many minutes - 1/60th , 1/30th ect to drop 2 degrees ( trying to get an idea how sensitive the movement is )

 

[Potomus Pete]

Half inch at a time. Slowly move and wait seconds for computer to catch up. You will hear whats up. I drove it and came back a few times. Half inch either way from where now.

 

[FastDriver]

Don't do it without a timing light unless you have no other choice. If you're not in a jam and still have no other choice, you have larger problems in life. Also, this is a math question. There are 360 degrees in a circle and there are 60 minutes on a clock. Therefore, every minute is 6*. Thus, 2* is 1/3 of a minute.

 

[MrPerfect2]

Ah - I get it now - the 2 degree move is out of 360 - makes more sense now , thanks !

 

[JD1964]

2 degree change in timing is a very very slight rotation. The mark you saw on the base of the dist and block was probably a reference point for removing and re-installing the distributor for whatever reason. The actual base timing should be set with a timing light. Even then you are working off the marks on the timing cover and harmonic balancer. Those are known to be not accurate sometimes. Finding true TDC on the balancer and marking it in relation to a pointer is the only way to be absolutely sure you are perfect. After you mark true top dead center you can put timing tape on the balancer which gives you the scale for advance and retard.

 

[revhead347]

Like other said, you are just pissing into the wind trying to set it by idle quality. It really needs to be set with a timing light. If you move it what you think will be 2 degrees, it will end up being 8 degrees, and your headers will start to glow. Also, it would take 4 degrees of distributor rotation to equal 2 degrees of timing, because the distributor turns at half the speed of the crank.

Kurt

 

[MrPerfect2]

Ah - so not 360 degrees but 180 degrees ? So just a nudge ccw should drop timing 2 degrees ? If this is so delicate of movement ( 1/180 ) how would a light help if I simply want to retard by 2 degrees)

 

[revhead347]

Ah - so not 360 degrees but 180 degrees ? So just a nudge ccw should drop timing 2 degrees ? If this is so delicate of movement ( 1/180 ) how would a light help if I simply want to retard by 2 degrees)

Well, first you need to clean off the harmonic balancer. Pull the Spout connector, and use the timing light to see where it's at. It should be around 10-16 degrees Advance base timing. Take that number, subtract 2 for your goal timing. Loosen the distributor, and rotate it so your base timing is now where your rudimentary arithmetic determines it should be. Tighten the distributor and then check it again to make sure it didn't move while you were tightening it.

Kurt

 

[TOOLOW91]

Buy a timing light . Your little nudge could end up being 4-6 degrees who knows . Not worth it to guess . Better off doing it right .

 

[OldManRiver]

An engine compartment is normally a pretty dark place,getting a little light in there will help you see what your doing.
At this point what else can one really say that won't get you banned for the rest of your life,and life of any offspring you have and any offspring they will have and ……...

 

[96pushrod]

Half inch at a time. Slowly move and wait seconds for computer to catch up. You will hear whats up. I drove it and came back a few times. Half inch either way from where now.

I will say that .5in of movement is a helluva timing change.

Any self respecting gear head should have a timing light. It’s as basic and necessary a tool as a socket set cold beer.

 

[General karthief]

Ok, before someone else jumps in here let me tell you 'what it be like'.
As someone has already said, first clean the balancer where the hash marks are, I brush white paint on the hash marks then take a sharp pointy thing and scrip a line at 0*, 10*, 12*, 14*, get the piston at tdc on the compression stroke, your balancer should be at 0* with the rotor pointing at #1 on the cap. This is done to make sure your balancer is good.
Now you have to use a timing light, pull the spout and set your timing, I set mine at 12* some set it at 14*, some at 16*. Just pay attention to spark knock.
To set your timing without a timing light is like putting air in your tires without a tire gauge.

 

[TOOLOW91]

Ok, before someone else jumps in here let me tell you 'what it be like'.
As someone has already said, first clean the balancer where the hash marks are, I brush white paint on the hash marks then take a sharp pointy thing and scrip a line at 0*, 10*, 12*, 14*, get the piston at tdc on the compression stroke, your balancer should be at 0* with the rotor pointing at #1 on the cap. This is done to make sure your balancer is good.
Now you have to use a timing light, pull the spout and set your timing, I set mine at 12* some set it at 14*, some at 16*. Just pay attention to spark knock.
To set your timing without a timing light is like putting air in your tires without a tire gauge.

Yeah and that detonation will come on strong on 87 pump gas .... I’d see if it’s even 10 to begin with . If not set it there and take it from there unless he plans on better fuel

 

[General karthief]

I should have mentioned 12* and 91 octane.

 

[MrPerfect2]

Ok - timing light it is - I did learn how to gauge a 2 degree rotation thanks to you guys !