engine and drivetrain Timing...something Doesn't Make Sense Here

[bruno615]

Hey all,

 

I am new to the world of timing.  I recently purchased an INNOVA 3568 timing light.  It seems to me that my engine does not run well at the suggested advance of ~30 degrees, but instead, likes ~60 degrees.  This does not seem right to me.  That being said, the car accelerates much better, runs smoother, and makes quite a bit more power, yet does not overheat.  

 

The story gets more complicated, as this is a recently swapped engine, built to an aggressive spec.  It has a very agressive cam, and therefore isn't the best idler to begin with.  Ported and Polished, lightweight internals, etc.  Compression, measured a few months ago, was 195 in all 4 cylinders.

 

I have recently replaced the spark plug wires and shortened them (the wire from coil to distributer was different from the rest, plastic core).  I run the bosch blue coil.  Distributer is #0231188002, which I believe is purely mechanical.

 

I just reset it from 42 degrees (where it was running really poorly), to 65 degrees, where it is totally alive.  The car performs much better, backfiring disappears, etc.

 

I sincerely doubt my 02 is different from the rest, so what's going on here?

Edited September 30, 2014 by bruno615

[Leitrum]

What kind of shape is your dizzy in? Any chance the flywheel was modified to go on differently than it should, or is the correct flywheel? What are you timing to? Past the Z ball? 

[Tommy]

Clearly your timing marks are off. The engine would not run with 65 deg advance so the measurement result must be wrong. -> Check your TDC and mark it clearly.

 

  Tommy

[TobyB]

Yup.  34- 40's the sweet spot at moderate to high revs on these engines.

 

TDC the engine, and make a marking line for the front pulley- it's a lot easier to use

with an advance light...

 

t

[M3M3]

I have to ask since you said you are new to timing... are you using the light correctly?

What are you using for timing mark?

64 degree minus the ball mark which is 24 degree equals the 41 degree of advance if should be running at. ...

[bruno615]

I'm using the ball bearing in the bellhousing inspection port.  

 

I've looked for a mark on the pulley, but don't think anyone has marked it previously.  

 

Does the ball mark 0 or 24?  If I make marks on the pulley at TDC, that spot = 0 degrees of advance?  (and then time to 30 degrees?)

[ray_]

The spec is 24* at xxxxrpm right? That's where the ball should appear in the light, if the light is set to 0*. Right?

 

Cheers,

[TobyB]

Z = tdc.  The ball bearing is something like 22 BDC...

 

if you have the sleeve in your crank, or it's aligned with the flywheel correctly.

 

Again, TDC the engine, and make a reference mark....

 

r

[thehackmechanic]

What folks are saying is:

 

--Set the engine to top dead center (TDC) by removing #1 plug, putting a thin rod, screwdriver, or a coathanger down the hole, and rotating the engine and feel the rod move up to its highest point, then come back down, then back up, etc, so you're dead nuts certain it's at TDC. THEN look for the TDC mark. Looking through the window in the top of the transmission bell housing, should be able to see the letters "OT" and then a vertical line. It's shown in the link below. Paint the line with Wite-Out.

 

http://www.bmw2002faq.com/topic/99003-cant-see-ball-on-flywheel-at-tdc/

 

--ONCE YOU HAVE DONE THIS, then you can look on the crankshaft --pulley for a top dead center mark. If it's there, it's little more than a small notch. If you find it, you'll see the pointer that it's supposed to line up with. If you see it, mark it and the pointer with Wite-Out.

 

--If, at TDC, you have a clear, unambiguous flywheel mark but do not have clear, unambiguous pulley mark, you can certainly mark the pulley and a reference location with Wite-Out anywhere you want, but this is why it is important to have absolutely no doubt that the engine is at TDC.

 

--Once you've found the TDC mark on the flywheel, it's a good idea to rotate the engine backward and find the timing ball, which is 25 degrees before top dead center, and mark it with a dot of Wite-Out.

 

--Now, with everything marked, you can time it. If you're using the timing ball, I believe the specs for a non-tii are 25 degrees BTDC at 1500rpm with the vacuum advance disconnected, and for a tii are 25 degrees BTDC at 2400rpm with the vacuum advance disconnected (if it has one).

 

--If you're not using the timing ball and wish to use the TDC mark and dial in the advance with your timing light, there's a previous post on it here:

 

http://www.bmw2002faq.com/topic/124816-using-an-advance-timing-light/

 

But don't ever use the timing ball AND dial in the advance on the advance timing light. That's probably why you're seeing numbers like 60. Either use the ball and no advance on the advance timing light, or use the TDC mark and dial in the advance on the light, but not both.

 

--Rob

Edited October 1, 2014 by thehackmechanic

[eurotrash]

The front pulley will have a little metal wart on the smaller diameter of the bell shape, before the pulley grooves.  This is the timing mark that will (normally) line up with the pointer on the chain cover when you are at TDC(notice the OT by the yellow line), or setting timing.. 

 

You should have around 7 degrees at idle.  So set the light to 7 and take a look see.  And then set the light to 25 and run the motor up to see where you get 25 degress of advance on the gun's tach.  Should be at about 1400 on a vacuum advance distrubutor, and I believe 2400 on a mechanical advance distributor, as if you set it with to the ball on the flywheel with the timing light at 0.

And then, finally, set the timing light to 32 degrees and see where that comes in.  Should be around 3k RPM.  If not, make it so.

 

..and then report back and tell us what you discovered, and how interesting this process can be!

 

Edited October 1, 2014 by eurotrash

[zinz]

Excellent description, Rob. 

 

Honestly, I'm very surprised that there isn't already a Tech Article on basic Ignition Timing...arguably THE most important factor on proper engine tuning and one question that is constantly being addressed on the main discussion page.

 

Ed

[ray_]

Excellent description, Rob. 

 

Honestly, I'm very surprised that there isn't already a Tech Article on basic Ignition Timing...arguably THE most important factor on proper engine tuning and one question that is constantly being addressed on the main discussion page.

 

Ed

 

 

Be our guest!

 

['76mintgrün'02]

I couldn't agree more with what Ed just said.  Including how-to instructions for plotting the curves as well.  

 

When I plotted the curve(s) I found it much easier (quieter) to set the advance to the next increment you want to plot, then rev up the rpms until the mark appears and read that number.  It beats having the engine running at 3k rpm while hunting for the mark, by adjusting the light.

 

Here is a link to the thread where I was having this kind of fun.

http://www.bmw2002faq.com/topic/155102-plotting-vacuum-advance-distributor-curves/

 

 

I would also like to see instructions for rebuilding distributors.  It seems almost taboo to take one apart, yet they all need it eventually.  I learned a lot by reading posts on VW sites.  They used very similar Bosch units.

 

It seems like it would be a pretty simple drill jig, to drill out the pin in the gear, which is the hardest part.  Such a jig would even eliminate the need of a drill press.  But, I digress.

 

I am eager to hear how you (OP) are able to dial it in and what sort of advance your distributor is providing. 

 

 

[M3M3]

I'm using the ball bearing in the bellhousing inspection port.  

 

As suspected, that is your problem. Follow the good instructions above to set it off the correct mark.

[TobyB]

I've "rebuilt" a half- dozen distributors.

 

The problem I always seem to run into is parts-

there are at least 6 different 2002 distributor

spec's kicking around out there, and 3 generations

of design, so getting parts (especially springs and weights) for the

unit you have IN YOUR HAND becomes really tricky.

And without an advance machine, confirming what you've done

becomes an engine tuning excercise- pretty frustrating.

And rebushing bodies takes a couple of specialist tools, and a 

source for the new bushings.

 

It's not hard to get one apart- drill the pin, pull the gear,

deburr the shaft, pull it out, check the parts and reassemble- 

 

and yes, there are a lot of VW parts that fit.  And they mostly work.

Early Volvo, too- 142s used this dizzy as well.

 

t