Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: Webby the Bear on 10 August 2014, 19:27:20

Title: Head skimming & 3L cams
Post by: Webby the Bear on 10 August 2014, 19:27:20
Hi ya,

Quick question.

I have two cylinder heads from my 2.5v6. I've removed valves as want them refurbed with new guides and stem seals (ALL guides are cracked from where the cambelt snapped).

Anyway, whilst having this done should I have them skimmed? Some say not to cos of the alteration to compression ratio.

Your thoughts welcome  :y

Oh and am I right in thinking that I can put 3L cam shafts in and not have to upgrade anything else???

 :y
Title: Re: Head skimming & 3L cams
Post by: minifreek on 10 August 2014, 19:54:05
Get the heads skimmed to bring them true again, no problem in having them skimmed and don't worry about the compression ratio....

Fit the G cams, Iv done the same to my 2.5 V6 but you will lose some bottom end torque (as I have), it's not much of a problem unless - like me - you tow a big caravan around the country and you need the bottom end grunt to get you moving better...
Title: Re: Head skimming & 3L cams
Post by: Webby the Bear on 10 August 2014, 20:20:48
Thanks MF...

Forgive my stupidity; what are G cams?  :-[
Title: Re: Head skimming & 3L cams
Post by: Nick W on 10 August 2014, 20:31:12
Skimming heads is worth doing if it's necessary. Check with a decent straight edge, and if they're not warped(which they almost certainly aren't) leave well alone. V engines can be problematic if heavily skimmed, as the inlet manifold might not fit afterwards. A clean-up skim isn't going to make any worthwhile difference to the compression ratio.

Fitting new valve guides will require recutting the valve seats; with 24 of the things that's going to be expensive, and in my opinion, hard to justify.
Title: Re: Head skimming & 3L cams
Post by: Webby the Bear on 10 August 2014, 20:38:24
Skimming heads is worth doing if it's necessary. Check with a decent straight edge, and if they're not warped(which they almost certainly aren't) leave well alone. V engines can be problematic if heavily skimmed, as the inlet manifold might not fit afterwards. A clean-up skim isn't going to make any worthwhile difference to the compression ratio.

Fitting new valve guides will require recutting the valve seats; with 24 of the things that's going to be expensive, and in my opinion, hard to justify.

Thanks for the info Nick.

On that basis I may scrap them then. And if I decide to put the3L cams in do it on the current heads that are fine  :y
Title: Re: Head skimming & 3L cams
Post by: minifreek on 10 August 2014, 20:43:19
The G cams are the 3 litre cams, fit 4 G cams for noticeable gains :)

OR

Fit 2 A cams on the exhausts and 2 G cams on the inlets as thats what they are anyway :) you will get gains and torque won't suffer...

Title: Re: Head skimming & 3L cams
Post by: cem_devecioglu on 10 August 2014, 22:55:56
Skimming heads is worth doing if it's necessary. Check with a decent straight edge, and if they're not warped(which they almost certainly aren't) leave well alone. V engines can be problematic if heavily skimmed, as the inlet manifold might not fit afterwards. A clean-up skim isn't going to make any worthwhile difference to the compression ratio.

Fitting new valve guides will require recutting the valve seats; with 24 of the things that's going to be expensive, and in my opinion, hard to justify.


agreed..


and install 3.0 cams and a 3.0 ecu ;)
Title: Re: Head skimming & 3L cams
Post by: minifreek on 10 August 2014, 23:02:18
Does the 3 litre ECU make a difference...?

Are they mapped differently to the 3.5's..?
Title: Re: Head skimming & 3L cams
Post by: cem_devecioglu on 11 August 2014, 14:34:46
Does the 3 litre ECU make a difference...?

Are they mapped differently to the 3.5's..?


I'm using a vauxhall 3.0 ecu.. before was an opel 2.5.. maps are definitely different which is also shown on the same dyno..
Title: Re: Head skimming & 3L cams
Post by: Webby the Bear on 11 August 2014, 14:39:56
So upgrade to 3L cams and i'm going to need a 3.0L ECU too?
Title: Re: Head skimming & 3L cams
Post by: 05omegav6 on 11 August 2014, 14:45:42
So upgrade to 3L cams and i'm going to need a 3.0L ECU too?
Not necessarily... The cams will improve things on there own :y

The full list would be...

4 G cams
3.0 long plenum
2.6/3.2 exhaust manifolds
3.0 Ecu
Ecu can be chipped to good effect as well.

 :y
Title: Re: Head skimming & 3L cams
Post by: cem_devecioglu on 11 August 2014, 14:55:03
So upgrade to 3L cams and i'm going to need a 3.0L ECU too?


nope..  only if you want a better pull :y
Title: Re: Head skimming & 3L cams
Post by: Webby the Bear on 11 August 2014, 14:56:02
So upgrade to 3L cams and i'm going to need a 3.0L ECU too?
Not necessarily... The cams will improve things on there own :y

The full list would be...

4 G cams
3.0 long plenum
2.6/3.2 exhaust manifolds
3.0 Ecu

 :y

Thanks Al,

i'll hunt for these G cams. When i want them (in the not too distant future) is an add on here the best way to get them?
Title: Re: Head skimming & 3L cams
Post by: 05omegav6 on 11 August 2014, 15:00:23
Zirk is/was flogging some :y
Title: Re: Head skimming & 3L cams
Post by: Webby the Bear on 11 August 2014, 15:03:07
Zirk is/was flogging some :y

Cheers mate  :y
Title: Re: Head skimming & 3L cams
Post by: omega3000 on 11 August 2014, 18:29:49
Just drop one of these in and be done with it  ::) :)

(http://i219.photobucket.com/albums/cc41/milleblack/20737f9b-f08c-4c98-a021-910b5f732662_zps5b0672af.jpg)
Title: Re: Head skimming & 3L cams
Post by: cem_devecioglu on 11 August 2014, 19:24:03
Just drop one of these in and be done with it  ::) :)

(http://i219.photobucket.com/albums/cc41/milleblack/20737f9b-f08c-4c98-a021-910b5f732662_zps5b0672af.jpg)


 ::)