m20/2.5 question

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Hoobs
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Post Wed May 30, 2012 8:45 pm

We did the cambelt on my 2.5 last week and noticed that, before removing the old belt, it was one tooth out! We checked a couple of times, just to be certain, but it was definitely a tooth out from the position it should have been. There had been no clue prior to changing the belt and the engine seemed to be running OK. It was about 10bhp down from stock on a dyno run (with a wild ECU chip fitted) but I put that down to age/wear & tear. Now, I'm wondering?

This may be a daft question but is there any reason why someone might deliberately fit a cam belt one tooth out? :mad:
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goosiegander
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Post Wed May 30, 2012 8:52 pm

Not unless they were bodging the cam timing in some fashion i would have thought, most likely just a lack of skillz...
Hoobs
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Post Wed May 30, 2012 10:20 pm

Would a single tooth make much difference to power output?
Rally Prep - Cornwall
ARM BMW & Motorsport
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kam-325i
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Post Wed May 30, 2012 10:23 pm

Hoobs wrote:Would a single tooth make much difference to power output?
Yes.

Example: The inlet Valves may be closing after the piston has started its compression stroke, resulting in lower pressure's.
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parkin10
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Post Wed May 30, 2012 10:43 pm

mine was a tooth out when i got it
the belt was very slack must have jumped a tooth