How do you check timing without a timing lamp?

[fronix4]

Hey guys, I suspect my Timing is off, but would like to test it prior to digging into it. My Rotor is pointing at wire 1 when off, but I noticed the notch in the bell is off by about 1/3 turn from the marks on the block. Any suggestions?

[BLHTAZ]

We need more info about what you are working on. Year & engine are most essential in answering this question ;)

 

If it's a 4.0L...you can not adjust timing.

[87ComancheLB]

So if you got a timing light and put it on the no:1 cylinder and strobe it against the timing mark and loosen the clamp on the distributor and tried advancing or retarding the timing it would not move?

[Eagle]

So if you got a timing light and put it on the no:1 cylinder and strobe it against the timing mark and loosen the clamp on the distributor and tried advancing or retarding the timing it would not move?

That's correct. The distributor has "ears" that lock it in one position. The timing is not adjustable.

[fronix4]

Well, it's a 86 comanche, 2.5 L 4 banger. I don't have a timing light. I know that the harm. bal. has a notch, the notch doesn't line up with the marks on the block, when the rotor is at tower 1.

 

Does this help at all?

[BLHTAZ]

Unfortunately, I am not familiar with that engine so we'll wait for another to reply as I am curious to learn something here myself.

[mjeff87]

when you say the rotor is pointing at #1 when off, are you sure you are at top dead center (TDC) on the compression stroke? Bring the timing notch on the HB around to "0" on the scale and see where the rotor is pointing.

 

Jeff

[fronix4]

When the HB is at TDC (0)...Center mark on the block, the rotor is about 1cm behind the 1 position. It is not on the 1. If the 1 were a clock figure, then the 1tower on the distributer cap is at about 5, while the rotor is at about 6.

 

 

Hope this helps!!!!!

 

 

 

Doesn't that mean the timing is retarded? Thanks for any input you have, and for your help.

[Eagle]

Well, it's a 86 comanche, 2.5 L 4 banger. I don't have a timing light. I know that the harm. bal. has a notch, the notch doesn't line up with the marks on the block, when the rotor is at tower 1.

 

Does this help at all?

The rotor doesn't line up with the tower when the timing mark on the vibration damper is at TDC (top-dead-center). It would line up only if the timing was to be set for exactly TDC ... but it isn't.

[mjeff87]

and if you look at the rotor tip, it is generously sized....I'd estimate there's about 10 degrees worth of timing across the length of it.

 

Jeff

[fronix4]

So we're looking at a timing issue for sure then? It is sure looking that way isn't it. It is not at TDC and at 1 at the same time. 10 degrees seems like a whole lot to deal with just to keep it idling. It would certainly make sense!

 

 

I'm going to rent a HB puller today, and replace all gears and tensioner/chain and seals. I can't wait to get her back to life!!!!!

[Eagle]

Yep.

 

Actually, the spark occurs when the leading tip of the rotor get close enough to the tower for a spark to jump the gap. In an old-style system, the rotor could be many degrees ahead of the tower and still be set to fire at TDC.

 

However, the engines don't fire at TDC, they fire before TDC. The amount of advance is controlled by the ECU, based on input from both the CPS and the camshaft position sensor (in the distributor). The ECU is what tells the system when to fire, not the position of the rotor. As long as the rotor is within the range that the spark can jump to the tower, nothing needs to be changed.

 

I assume this is related to your other post about flames shooting out of the throttle body. Yeah, that problem could be timing related -- but timing in the sense that the timing chain may well have jumped a tooth (or several teeth). That would result in the distributor and the camshaft (meaning the valves) all being out of synch with the engine. You can't solve that problem by just turning the distributor. You need to open up the timing cover and verify whether or not the cam sprocket is still in the correct relationship to the crankshaft sprocket.

[fronix4]

Yeah, I remember those older engines, where you could just listen to the cam and adjust the timing. I am working on getting the HB puller so I can see if everything is lined up. I really hope it is off, so I will have it running again.

I hope to have the hb and cover off today.

 

 

The truck was so busted when I got it. I've done a lot of work to it, but it will always be a work in progress. These trucks are too good to let rust in a field and die.

 

 

Thanks Eagle.

[Geonovast]

You need to open up the timing cover and verify whether or not the cam sprocket is still in the correct relationship to the crankshaft sprocket.

 

How do you know the sprockets are in relation to each other correctly?

 

I'm about ready to pull the timing cover on this XJ.

[mvusse]

When the timing mark (dot) on the camshaft sprocket is pointing straight down, the one on the crankshaft sprocket should be straight up. If you're off even 1 tooth, it should be quite obvious, even though 1 tooth off would probably still run, albeit like crud.

[Randy in Maine]

Just buy a timing light and cut to the chase.

[FxRacing282]

they are not cheap and you can do the timeing and bring it back and say it was defective and get your money back

[Eagle]

:yeah that:

they are not cheap and you can do the timeing and bring it back and say it was defective and get your money back

Nice.

[Randy in Maine]

You can buy a decent timing light for cheap money.

 

E-barf has some but I bought mine at Sears (with the crank in centrifical advance) for $70 about 5 years ago. Money well spent.

 

http://www.sears.com/shc/s/p_10153_12605_00921023000P

[FxRacing282]

to some of us 70 is a good bit of money. and to others its not.

[HOrnbrod]

to some of us 70 is a good bit of money. and to others its not.

 

Yeah, I guess that justifies buying a timing light or some other tool from a merchant who's trying to make an honest living, using his product, then bring it back and lie to him/her and get your money back. Sorry man, that's just warped. :nuts:

[fronix4]

Mine had a bad tensioner....if I line the two sprockets up like you said, should the rotor cap point at 1?

[mjeff87]

From what I remember when I did mine, no. When the cam and crank sprockets were lined up by the marks, my rotor was pointing somewhere around 10-11 o'clock.

 

They can really only go on one way, because of the locating pin in the front of the camshaft that engages the hole in the cam gear and the key on the crank snout that lines up with the crank gear.

 

Jeff