Timing Issues

[Calloway]

Alright guys, try to wrap your mind around this one...

After doing an engine rebuild on my 90 B2 with the 2.9, I can't get the thing timed right again. I replaced the timing set (gears and chain), double and triple checked it to be sure it was correct. So to get everything "close" to being timed I put the #1 cylinder on TDC, installed the timing set (marks pointing toward each other), then installed the distributor with the rotor pointing toward the #1 spark wire stud on the cap. I started it and it ran but not the way it should be. After putting a timing light on it, it showed it was firing late but had the correct RPM's it needed to run at (850 in my case), and the closer I adjusted the timing toward 10 degrees BTDC the RPM's climb toward 1500. It also smells to be running rich which I can understand if its firing late.

Any help would be much appreciated because it's got me stumped. I've done all the work regarding my B2 and I know the thing inside and out, I'm just anxious to get her back on the road...

 

[Gilbee01]

I think I remember something about removing a vac line before setting.. Might want to look into that . Or you may be 180 off when you installed . Just a few top of the head thought

 

[RonD]

OK, valve timing and spark timing are two different things.

Assume Timing chain is set up correctly if engine starts, might not be but lets just assume it is.

Distributor can, and is, adjusted on it's own, yes it does run off the cam but on a separate gear that can be adjusted.

You should have a TFI system on a 1990 B2.
To set the base timing you need to remove the SPOUT connector, this keeps the computer/module from adjusting the timing while engine is running.

have a read here about TFI systems:
http://www.therangerstation.com/tech_library/TFI_Diagnostic.html

 

[Calloway]

OK, valve timing and spark timing are two different things.

Absolutely, I was just worried that my lack of focus may have gotten the timing set a tooth off or something of the sort. Now the TFI has more to do with electrical spark right? All cylinders are firing and I don't believe there's a spark problem as of now, it seems to be more of a timing problem on the distributor...

Let me set up a hypothetical scenario that I've been thinking about. So lets say that my ignition is so late, that the engine is running around 850 RPM's (rich exhaust gas, and NO horsepower either by the way). When I try to adjust toward 10 degrees BTDC, the RPM's rise because I'm bringing the spark closer to the top of the cylinder stroke. Then once I peak over the top of the cylinder stroke (to where it should be) it will level out again.

Could this be possible? If I kept adjusting over the top of the cylinder stroke my timing marks would come back into view and that would be it? This is just something I've been wondering about and don't know if it's even possible.

 

[RonD]

You can't really adjust the timing............the computer is changing it while you are moving distributor, so you are basically chasing your tail, because it won't stay where you put it the next time you start the engine.
First disable the computer control, start engine, set base timing at 10deg BTDC, shut off engine, then restart with computer reconnected so it can relearn correct timing.

The computer doesn't know 10deg BTDC from a hole in the ground, it is set up to control spark timing on the "assumption" the base timing is at 10deg BTDC, because that is the factory setting.

I too miss the old days when timing stayed where you put it or where the vacuum advance put it, lol.

Yes, spark far enough after TDC will lower power, but far enough before TDC does as well.

 

[Calloway]

Where exactly would I disconnect the computer at? I see what you mean about the timing changing from where you leave it, because i went to start it today and it won't even run. I'm starting to think I should have dropped something carburated into it... this is a real p.i.t.a.

 

[Calloway]

Alright nevermind RonD, I called a good mechanic buddy of mine up and it looks like everything is good to go He just made a few small adjustments and she ran better than ever! I'm just glad to have her back on the road again! Thanks for your help.

 

[RonD]

Good work :icon_thumby:

 

[kimcrwbr1]

To adjust the timing you need to disconnect the spout jumper that runs the engine at base timing. After making the adjustment then plug the spout back in and go. Just for future reference.

 

[Gilbee01]

-gil-