MatraSport Forum

Quote from: macaroni on May 29, 2008, 02:59:08 pm
Can you tell me the valve clearances also please?


Inlet: 0.2 mm
Exhaust: 0.3 mm

Cold engine.


However, that is for the standard cam, Anders.

The Holbay cam has slightly different settings.

The inlets should be: 0.25 mm (10 thou)
Exhausts as original: 0.30 mm (12 thou)

Roy
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Would the Politechnic 150cv cam valve clearance settings be the same as the Holbay cam or different again anyone?

Thanks Graham

Question answered:


Les jeux de fonctionnement pour Murena 2.2
Tous type arbres à cames (origine - MATRA K142 - Politecnic 153)
 
Culbuteur admission :  0.20 mm
Culbuteur échappement : 0.30 mm
 
Politecnic sarl
Cyril Gracia

A little odd that they quote that for all cams when Holbay wants 0.25 on the inlet side...

I would love to set the clearance on my Holbay cam.  ;) Problem is I do not have a Holbay cam. :(

So where can I get one, or at least a "S" cam? ??? Does anyone of you have an extra laying around, that you would consider parting with?  ;D ;D

No, I don't have a cam you can have ;D
But call these guys, they still make them:
http://www.coltecracing.com/

/Anders

Hi Anders.
Thanks, I will get in touch with them.
But what about the lifters? will I need to replace those? ???
I didn't think you'd part with a cam, just out of the goodness of your heart :D I know they are expensive if you have to buy them from Simon or Politecnic. So I was prepared to part with an appropriate amount of €€€, £££ or $$$ ;D ;D ;D

Yes, you will have to replace the lifters. However, Roy has reported that Coltec can refurbish old lifters and I happen to have two extra sets lying around here, so if they can't supply you new ones, I think we can work out a deal and you can have an extra set for refurbishment.

Then you can save your old cam with it's lifters. Used lifters and used cams belong together like your feet and your shoes: They may still be perfect on you, but won't fit anyone else after you've worn them for a while.

Mixing old lifters with a new cam will cause cam wear.

/Anders

Didn't think Coltec made cams, but they will re-profile existing ones if not too badly worn and they have all the Matra profiles.  The company is formed from the remnants of Holbay after they went out of business some years ago.  They are actually a few minutes away from where I live and they've done a lot of engine work for my ongoing 1.6 re-build, including a cam re-profile and refurbished cam followers and rocker arms.  Can't comment on the work until I've put it all back together and started it up  :)

Just an update, I have spoken with Richard (owner) at Coltec Racing today and they will be moving soon and will no longer be re-profiling cams I'm afraid.  So we will have to find somewhere else in future. :-(

Roy

That is strange. I just today received an answer from Richard where he says that he can reprofile my cam and refurbish my lifters. He did not say anything about stopping doing that.  ???

I visited Coltec today and I can confirm that they are moving to Hollesley (pronounced "Hosely"), still in Suffolk but not quite as convenient for me!  They have decided not to take the camshaft machine as they say there is no demand for camshaft grinding these days.  I think the Matra Club must be the only customers!  If you want to protest, all email Richard@coltecracing.com now. :)

I will ask him if I can have the camshaft grinding machine.  :D
My cam is still in the engine and in the car. There is no way I can get it to Coltec before they move.  :(

Anyone ever compared the 505 turbocam with the one in the Murena's?
I asume it is a faster cam, and would it be usable in the Murena engine?

I doubt the cam or profile for the Peugeot 505 Turbo would be suitable for a naturally aspirated Murena 2.2

As far as I was aware, only the cylinder blocks are the same.  (The Murena block was used as it is stronger than the Peugeot one)  The heads and therefore the cams are different.  Maybe someone who has one can confirm.  However, the profile and timing are the important parts along with the amount of lift, and the needs of the two engines would be different.

With natural induction, as the piston speeds up going down it pulls more intake.  With a forced induction, it doesn't rely on piston position so much so the valve position/opening should be different to suit.

Roy

Thanks Roy for your opinion on that.
The reason I asked is that I have this cam (still build in a turbo cilinderhead) and was thinking of using it, but  had my doubts.
I also have a original 2.2 Murena cam and a Tagora cam.
I like to use the turbohead, and it was revived not long ago along with nicasil coated valves..
Think I put the Murena cam in there to build a standard engine.

I just had a nice phone conversation with Richard at Coltec Racing. He has shut the current shop down and was in the proces of moving.

However, in a month or two, when he is settled in at the new place, he will be doing cam reprofiling again. He has sold the machine, but the new owner will let him still use the machine and he will be able to do the Holbay profile.

I was trying get the profiling done before he moved, and Anders has kindly lent me a spare cam and lifters, that he had laying about, so I could get it done before Richard moved and so I can keep driving while the cam is being worked over.

I will just have to be patient, but since I probably won't get to do the work until this summer anyway there is now no hurry.  :)