Timing belt question

[itsonlygeorge]

I replaced the timing belt and noticed that the cam gear was one tooth before the tick mark while the lower crank is right in the notch.

I left it in the same spot when I replaced the timing belt. I am about to put everything back but wanted to check first.

Does this indicate that the timing has been retarded?


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[Cabriolet]

means you did it wrong. take it apart and do it right.

[itsonlygeorge]

All I did was keep the cam/crank in the same spot that it was originally.


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[turbo55]

All I did was keep the cam/crank in the same spot that it was originally.

All that means is that whoever did it last screwed up, or something was very wrong with the belt or tensioner and it skipped a tooth. All the notches must be lined up (crank vibe damper+housing notches and cam sprocket+head notches). After putting a belt on with them lined up crank it over at least 4 times with a wrench to make sure it's still perfect.

[itsonlygeorge]

Can someone please clarify which way timing is retarded vs advanced? Is CCW retarded and CW advanced? Since I an off a tooth I just want to understand what the base condition my engine has been running if the timing belt has been wrong now.


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[uturn]

The engine spins CW. If the cam mark is on the right of the mark on the head then it is advanced. Assuming the head and gasket are original specs.

[itsonlygeorge]

Right now, the cam mark is before the mark on the head. (on the left) So that means timing has been retarded?

The previous owner ran a 027 ecu with a markD chip. Could he have retarded the cam timing for improved high rpm power? What would this do in conjunction with the markD chip?


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[uturn]

Off by one tooth but the bigger issue are the stamped gears. Get those two replaced with the new style ones.

[itsonlygeorge]

The previous owner last did a timing belt change 2 years ago and it looks like he retarded the cam timing by one tooth, either on purpose or by accident. He ran the 027 ECU with the MarkD EAT chip and 91 octane. The car ran fine, but had a rough idle when cold (it would drop low then bounce up to 900, and stabilize in a few minutes). This was pronounced when it was sub-freeing outside.

I have since removed the ECU and ran an stock ECU with regular 87 octane gas and the idle has not improved, and of course the engine does not pull as hard.

My question is this:

If the cam timing was retarded mechanically, but the ECU timing was advanced what is the effect on the engine?

Should I leave the timing as it was or advance it to TDC? Is it worth it to advance it one notch further past TDC?

I do plan on putting the ECU w/ the MarkD EAT chip back for the spring/summer and want to make sure I have a reliable and fun car to drive. This is a DD, not a track car, although I drive it aggressively :)

[itsonlygeorge]

Off by one tooth but the bigger issue are the stamped gears. Get those two replaced with the new style ones.

I am aware of the stamped gear issue, they are only available from the dealer, and I am unsure how to change the bottom gear. I am sure you need to remove the bottom timing belt cover and put new gears on, but I just didn't have time to do it.

I wanted to get the car on the road and I didn't want to take the gears off since I haven't done this before. My issue was a leaking water pump, the timing belt is getting replaced at the same time and I ran into this issue.

I am sure that I can change them down the line if I boost.

[itsonlygeorge]

I have been reading these articles to learn more about the effects of timing retard/advance. Just listing them as a reference.

http://www.hamotorsports.com/cam-gear-tuning.html

http://www.hotrod.com/how-to/engine/...ng-a-camshaft/

[Northern]

I am aware of the stamped gear issue, they are only available from the dealer, and I am unsure how to change the bottom gear. I am sure you need to remove the bottom timing belt cover and put new gears on, but I just didn't have time to do it.

It's easy to swap the intermediate gear. The new gear was $22.60USD new back in 2013 through blunttech. I wouldn't be surprised if BMW's price on that has gone up a little though. Cam gear can't be much worse price wise.

I also recommend running timing the way it is marked unless your engine is significantly modified, in which case you should have an adjustable gear if you want to play with cam timing.

[itsonlygeorge]

So, to adjust it back to stock I should turn the cam gear CW one tooth while keeping the crank lined up?

[uturn]

Yes, then do what turbo55 said about turning it over by hand to ensure the marks still line up.

[itsonlygeorge]

It's easy to swap the intermediate gear. The new gear was $22.60USD new back in 2013 through blunttech.

3-5 days lead time from blunttech, and ~$35 for the cam gear. Not sure the lower one. Probably something similar.

I am not trying to play with timing, just figure out what was previously done to the engine, and get a baseline for what it was running like and why.