Can Someone Please Explain Timing?

[1986ranger]

OK, I am troubleshooting a truck and ran into something I don't understand. I understand when you pull the SPOUT it is locked at base timing. So with the timing light connected to the number one plug wire, the timing pointer on the balancer should be at the 10* mark. In an attempt to see if the others were getting spark from the distributor, I checked the timing on the other cylinders just to make sure there were at least making the timing light flash. When I did this, they all were making the timing light go. This, I thought, was good. Now here is where I get confused. On all 6 cylinders the timing light illuminated the balancer in the exact same spot, on the 10* mark. I check this on another known good running truck and got the same results. How is this possible? Keep in mind this was was all done with a VERY cheap timing light.

 

[Earl43P]

http://findarticles.com/p/articles/mi_qa3828/is_199907/ai_n8876015

 

[1986ranger]

http://findarticles.com/p/articles/mi_qa3828/is_199907/ai_n8876015

How much of that applies to an '87 2.9 with a distributor?

 

[85_Ranger4x4]

It is impossible to have spark going to all of your plugs at the same exact time. You have a rotor that spins inside the cap, as it spins it contacts a lead that goes to each spark plug wire, it can not touch all the leads at the same time... and if it did your engine wouldn't run. I guess it could be close, but it can't be the exactly dead on.

I say try a different timing light to be sure.

 

[1986ranger]

It is impossible to have spark going to all of your plugs at the same exact time. You have a rotor that spins inside the cap, as it spins it contacts a lead that goes to each spark plug wire, it can not touch all the leads at the same time... and if it did your engine wouldn't run. I guess it could be close, but it can't be the exactly dead on.

I say try a different timing light to be sure.

I agree. And in theory, shouldn't the sparks be significantly far apart, like 120* apart? According to what I saw, they were at the same spot. I am going to try another timing light, but I don't see how it could be malfunctioning and producing such consistent results.

 

[85_Ranger4x4]

There isn't a setting on the light that isn't set right is there? You might double check the instructions if you have them to make sure you have it set up right.

 

[1986ranger]

There isn't a setting on the light that isn't set right is there? You might double check the instructions if you have them to make sure you have it set up right.

Don't think so. It is as basic as they come and was dirt cheap. I did check the directions though. I may have to invest in a better one.

 

[MAKG]

I suppose it MIGHT get tripped by "crosstalk" if the pickup were excessively sensitive. That would mean it lights at 3x idle speed (so it shows at 10 deg BTDC, 110 deg ATDC and 130 deg BTDC for every cylinder).

Any wire will pick up signals in a nearby wire, though one would expect this to be a very small effect.

 

[Insanejughead]

Do you realize that when you hook the timing light into one cable that you are checking the timing on that particular cylinder?

Just because #1 fires at 10*btdc doesn't mean that cylinder #2 is going to fire at 40*btdc... Each cylinder fires when THAT piston is at 10*btdc.


If this doesn't help you then I must not have understood you completely. Your wording did screw me up a bit.

 

[85_Ranger4x4]

Do you realize that when you hook the timing light into one cable that you are checking the timing on that particular cylinder?

Just because #1 fires at 10*btdc doesn't mean that cylinder #2 is going to fire at 40*btdc... Each cylinder fires when THAT piston is at 10*btdc.

Yeah but the marking on the pulley should only apply to #1, not all 6 cylinders.

 

[lil red]

y would you check it on the other cylinders anyway, there all conected, id get a better light and only check #1 and be golden

 

[MAKG]

As the original poster mentioned, it's a good test for spark on each cylinder. That's a bit more specific than a cylinder balance test.

Though I really wouldn't bother unless I was diagnosing a rough idle.

 

[reno]

oh, I thought you meant a different kind of timing, like good timing and bad timing.

Good timing is seeing the woman of your dreams and scoring a date.

Bad timing is, as you are scoring that date your current G/F or Wife walks in.....

 

[red85]

oh, I thought you meant a different kind of timing, like good timing and bad timing.

Good timing is seeing the woman of your dreams and scoring a date.

Bad timing is, as you are scoring that date your current G/F or Wife walks in.....

Bastard stole my line!!!!

 

[shadetree]

Do you realize that when you hook the timing light into one cable that you are checking the timing on that particular cylinder?

Just because #1 fires at 10*btdc doesn't mean that cylinder #2 is going to fire at 40*btdc... Each cylinder fires when THAT piston is at 10*btdc

Correct. You get the gold star. I'm surprised the mighty brain of tech support didn't point this out.

All plugs fire at the same number of degrees before TDC when that cylinder is compressing and getting ready for the power stroke. Number one is used for timing convenience and as a standard. Why would you use #6? However,I have seen some cases where another cylinder is used for initial timing by another mfgr. I don't remember which one(s) right off hand.

You can time the distributor with any cylinder as long as it is at the top of the compression stroke, and the distibutor rotor is pointing to the plug wire for that cylinder. shady