I recently completely removed the whole distributor, and in the process of putting it back in I lost all sense of the exact position, so timing is a bit off. This was a complete abortion as now I'm not sure what spark plug goes where from the engine to the distributor as well, and after an hour and thirty of internet research I still don't have a good idea of what to do.

I think first I need to determine exactly which spark plug wire goes where on the distributor first. Can anyone help me in that regard, perhaps a diagram of some sort. Then from there I can find the right timing by rotating the distributor little by little until the engine fires up...it can't be that off I believe. But if I am, then what? Is there a tech article that you guys can point me too. I have a 91 C4 L98.

 

http://members.shaw.ca/agent86/Spark...g%20Wiring.pdf

 

This problem can seem complicated, but it is really simple. You should be able to orient the distributor in approximately the correct position by the wiring harness that go to the cap and distributor. Place the dist and cap in the best guess position. Assume that 12:00 is the front edge of the distributor, toward the radiator. The wires should be placed in the distributor cap in the following order.....starting with the first dist cap spark terminal at about 1:00, cylinder numbers 1, 8, 4, 6, 3, 5, 7 then 2. Do this in a clockwise rotation while looking down at the distributor. You will end up having #1 cylinder wire on the distributor at the 1:00 position, #8 at 2:30, #4 at 4:00, #6 at 5:30 and so on! This should allow you to start the engine and fine tune the timing. Warning, make sure #1 cylinder in at the TDC, FIRING POSITION when the rotor is pointing at the #1 wire terminal. It is possible to place the distributor 180 degrees out of position by not knowing when #1 is a TDC firing position.

 

I would go ahead and find #1 cylinder TDC. Take #1 spark plug out and place your finder over the hole. Turn the engine over until the pressure pushes your finger off the hole. Check to make sure the timing mark on the balancer is at 0*. Now you will want to insert the dist so at the rotor is pointing at #1 spark plug or at the left rear corner of the plenum. It might take a few tries but it will go in the correct position. Once it's in reconnect the wiring and install the cap. Do not tighten the dist down until you get it were you want it. The link AGENT 86 posted should give plug wire positions.

After it's sorted out and everything is connected, disconnect the EST wire and tighten the dist hold down bolt so that the dist will still turn with a little effort. Start the engine and use a timing light and turn the dist to 6* BTDC. Tighten the bolt and recheck. Stop the engine and reconnect the EST. Disconnect the battery to clear the code and start the engine again. The timing will be around 22-24* or 12 o'clock on the balancer.

 

Alright, need some quick help if possible, before I take #1 out and put my finger over the spark plug hole, should the distributor be mounted at this point? I assume it should be mounted with the distributor cap off, but I'm not too sure here.

 

Last time I did it the dist was in. Just disconnect the wires. I took #1 plug out and placed my finger over the hole and with my other hand...turned the key.....not like cranking, but like bumping the starter a few times before it blew my finger off. I just could use both arms doing this. Then check to see if the mark on the balancer is at 0*. Then you know your #1 piston is TDC. Then get the dist to fit where the rotor is pointing at #1 or at the left rear corner of the plenum.

 

Alright, after it blows my finger off, and the mark on the balancer is at 0....should I then need to completely remove the dis. out from the car and then put it back in so that the rotor is pointing at 1?

 

Lol, hate to read about this. I will never forget the first time this happened to me I was 15, and just about s**t a brick when I realized what had just happened. Luckily, I finally figured out the basic principles of magnetism and was able to get through it. But god, I was petrified doing it!!

 

Chickmagnet: Once you get the TDC mark at the "0" on the block marker, then remove the dist cap and see where the rotor button is pointing. It should be pointing to the position where the #1 cylinder wire is attached to the distributor cap. If this is not the case, remove the distributor and realign the rotor such that it points to the #1 terminal when the dist is fully seated to the intake. Hope this makes sense.

 

Thanks a bunch Sam, it does make sense. i'll give it a shot tomorrow as it's too dark out now.

 

Yep, if you left the dist in and got #1 to TDC, remove the cap (if you haven't already), and note the rotor is not pointing at #1 cylinder.....pull the dist. Realign it so the dist/rotor to point at #1. This may take a few tries by moving the oil pump shaft with a long screwdriver (make sure the dist gasket is on and that the dist seats all the way down on the intake manifold). It will eventually go in. After it looks right, go ahead and place the cap back on and spark plug wires in the correct places. Connect the wiring and tighten the dist hold down bolt just a little so the dist still turns will a little effort. Put #1 plug back in and connect the wire. Disconnect the EST wire and start the engine. Use a timing light to get the HB mark at 6* BTDC and tighten the hold down bolt. Recheck before shutting the engine off. Reconnect the EST wire and disconnect the battery to clear the code. Start the engine.

 

ok, I understand everything except for this part above. never used a timing light before, can I get this at auto zone? the 6* at BTDC, is that a measurement taken from the timing light. Also which one is the EST wire. sorry, this is all new to me.

 

I was wondering why it is necessary to keep my finger over spark plug 1...why can't I just start it without spark plug one plugged and then check to see if at's zero. I only ask because I tried it without my finger on the hole as I didn't have an assistant...and it would get close to line up at zero...but it would never be exact. So that much be why I cover the hole right?

 

U have to keep ur fingers at spark plug hole b/c while either cranking by ignition or turning engine by hand, u get pressure keep coming from hole till the piston reach tdc, the moment u feel no more air from hole so u know that its at TDC, stop there.

 

To really understand this, you have to go back to the basics of your engine design.

There are four strokes - intake, compression, power, and exhaust

From top dead center (TDC), the intake stroke is initiated by the piston moving down to bottom dead center. During this period, the intake valve closes (the exhaust valve has already closed long ago).

The piston then starts back toward TDC, compressing the mixture drawn in while the intake valve was open (compression stroke).

When the piston gets to TDC, the spark ignites (actually, the spark fires a few degrees BEFORE TDC), and the rapidly expanding gas pushes the piston back to BDC.

The inertia gained from that explosion causes the piston to continue past BDC, and the open exhaust valve allows the spent gases to escape through the exhaust manifold. Then, of course, the piston is back to TDC, and the intake stroke begins again ...

So, the reason you need to have your finger in the hole is so you know if the piston is on a compression stroke or an exhaust stroke. If you make a mistake at this point, the engine timing will be off by 180 degrees, and the rotor will be pointing exactly opposite of where you really want it!

Once you've given this some thought, you'll understand it better. This will be even more apparent if you remove the distributor cap, and observe the compression and exhaust stroke with respect to where the rotor is pointed.

Good Luck!

Steven

 

Also, assuming you understand all the previous, you may want to pack a small, clean tightly wound rag into the aprk plug hole of cyl. # 1(forwardmost cyl-toward front on drivers side)(instead of trying to use your finger-too difficult esp. if working alone). You'll hear a "pop" as you "bump" the key switch(don't crank it). Just "tap" the key. Stop as soon as you hear the pop. Put the trans. in gear and "rock" the car 'till the timing marks(previously wiped clean/marked with paint, etc.) line up. Now insert the distributor (cap removed) with the rotor aimed at what would be "terminal # 1 ". The rotor may actually point ever-so-slightly past (clockwise) the location of cap terminal #1, but not at the "next" terminal. Drop the distb. in. You may have to "anticipate" the rotation of the rotor clockwise to get a dead on drop in. Get familiar w/ FIRING ORDER & cyl. # designation and trace the wires from the distb. to their respective plugs/cyls. Proceed as others have suggested re. setting basic timing. Good Luck

 

I was able to try the method and when the key was turned there would be a time when it blew my finger off. but usually the line on the balancer wouldn't be exactly at zero but very close. Does it have to be dead on? Any how when it blew my finger off I checked where the rotor was pointing and it was definitely not pointing any where near #1. I then took it off orientating the rotor towards the #1 position but I couldn't get it flush...then I ran out of daylight. Does it matter which way the metal base of the distributor goes...because that's the only thing that moves when everything is mounted. I was unsure as to whether the base needed to be marked and orientated a certain way as the rotor. From what I gather it's just the rotor that needs to be pointing at 1 once I get

And I'm not sure as to whether I should adjust the oil shaft....will this throw everything off...or should I simply be able to remove the distrib. and drop it in with the rotor pointing at 1 once I get TDC.

 

You don't need to adjust the oil shaft at all. You might need to spin it a little to get the distributor gear to line up with it if you are reinserting the distributor in the engine.
Once you get the engine close to the #1 TDC position you should be able to roll the engine slightly by hand to align the timing marks up perfectly on 0 degrees. Only then can you insert the distributor in the engine with the rotor pointing roughly towards the drivers tire and as you drop it in the rotor will engage the drive gear on the camshaft and will roll to its final and correct spot pointing to the 1:00 oclock position as earlier described. This is really nit picky but it must be done right to work right. I hope this helps a little at least.

 

thanks for the clarity, and for everyone chiming in, i really hope to get back on the road soon

 

Hey guys, the good news is that after setting the car to TDC it started. I want to thank all who responded and helped me on my quest to get the monster back on the road Before the timing issue I had an intermittent starting issue which I attributed to the ignition module. After fine tuning it is running great, but I think there is a notable loss in performance however, and I think this may have to do with the timing. It seems that I lost a lot of low end off the line power. I also want to be sure that I fine tuned it correctly, and if 6 btdc is the best setting for a 91 L98.

I think it's at 6 btdc, though I could be wrong. Right now the line on the balancer is set at 6 below the 0 mark on the balancer. I think this is BTDC. My question is should it be set at 6 above the 0 on the balancer. Again, I seemed to of lost that off the line power...and most of the power seems to come in at the high RPM now. I use to be able to launch and lose traction due to all the power, but now the power just isn't there at the low end. Any ideas?