Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: kcl on 09 May 2011, 09:34:48

Title: Engine vibration, timing?
Post by: kcl on 09 May 2011, 09:34:48

How "exact" must the timing be? I wonder this because I have noticed that my engine vibrates slighlty on idle and can not remember if it did that before the cambelt job. How much will it effect the idle if timing was, let's say, less than a quarter of a tooth out on one side? Mine runs nicely though, fuel economy is ok, pulls very nice and smooth, only this vibration on idle...which could be a dozen other things also.

Title: Re: Engine vibration, timing?
Post by: Jimbob on 09 May 2011, 09:39:01

Split form other topic to keep both threads clear and on track.

Title: Re: Engine vibration, timing?
Post by: feeutfo on 09 May 2011, 10:06:29

It will idle fine if a quarter of a tooth out ime.

Also, to add to the list of possibles, non drive by wires run, not lumpy, but less smooth with ac off ime. So if the ac is not working....
Just a thought. Could be a number of things though as you rightly say.

Title: Re: Engine vibration, timing?
Post by: kcl on 09 May 2011, 10:30:26

Thanks, I'll really sleep better hearing that  :y

So, in general, what would be the limit for the timing being "out"? Two teeth is a disaster, one tooth causes rough running (really rough? How rough? Throughout the rev scale or just the idle?), less than a tooth out causes what?

Title: Re: Engine vibration, timing?
Post by: feeutfo on 09 May 2011, 11:04:46

Quote

Thanks, I'll really sleep better hearing that  :y

So, in general, what would be the limit for the timing being "out"? Two teeth is a disaster, one tooth causes rough running (really rough? How rough? Throughout the rev scale or just the idle?), less than a tooth out causes what?

I would guess power would suffer in a direct proportion to cam timing accuracy as revs rise. If you want an efficient and as economic an engine as possible i'd get a kit and re set it correctly.

I've seen cam timing out from the previous install to varying degrees, smoothness and eagerness improves with cam timing accuracy throughout the rev range. But I've only seen up to 1 tooth out. Tick over was ok though as I recall.

Title: Re: Engine vibration, timing?
Post by: kcl on 09 May 2011, 13:46:52

Quote

Quote

Thanks, I'll really sleep better hearing that  :y

So, in general, what would be the limit for the timing being "out"? Two teeth is a disaster, one tooth causes rough running (really rough? How rough? Throughout the rev scale or just the idle?), less than a tooth out causes what?

I would guess power would suffer in a direct proportion to cam timing accuracy as revs rise. If you want an efficient and as economic an engine as possible i'd get a kit and re set it correctly.

I've seen cam timing out from the previous install to varying degrees, smoothness and eagerness improves with cam timing accuracy throughout the rev range. But I've only seen up to 1 tooth out. Tick over was ok though as I recall.

Well, it was my first belt and I had fewer adjustable rollers as in DVD. When the marks were spot on I could not remove the other locking key at all so I had to slacken the belt from that side  :-/

Title: Re: Engine vibration, timing?
Post by: chrisdb on 10 May 2011, 20:01:11

Quote

How "exact" must the timing be? I wonder this because I have noticed that my engine vibrates slighlty on idle and can not remember if it did that before the cambelt job. How much will it effect the idle if timing was, let's say, less than a quarter of a tooth out on one side? Mine runs nicely though, fuel economy is ok, pulls very nice and smooth, only this vibration on idle...which could be a dozen other things also.

Could be the idle control valve. I had this once and Mark DTM kindly showed me how to clean it out.

Title: Re: Engine vibration, timing?
Post by: kcl on 11 May 2011, 08:01:32

But mine is dbw so no icv on this engine....

Title: Re: Engine vibration, timing?
Post by: feeutfo on 11 May 2011, 09:07:42

Quote

Quote

Quote

Thanks, I'll really sleep better hearing that  :y

So, in general, what would be the limit for the timing being "out"? Two teeth is a disaster, one tooth causes rough running (really rough? How rough? Throughout the rev scale or just the idle?), less than a tooth out causes what?

I would guess power would suffer in a direct proportion to cam timing accuracy as revs rise. If you want an efficient and as economic an engine as possible i'd get a kit and re set it correctly.

I've seen cam timing out from the previous install to varying degrees, smoothness and eagerness improves with cam timing accuracy throughout the rev range. But I've only seen up to 1 tooth out. Tick over was ok though as I recall.

Well, it was my first belt and I had fewer adjustable rollers as in DVD. When the marks were spot on I could not remove the other locking key at all so I had to slacken the belt from that side  :-/

Yes cams 3+4 are set on the later v engines there is no adjustment needed other than to engage the correct teeth.
So in theory only 1+2 should be out adjusted by the top roller.
I'd get a kit and re set it tbh.