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  #31  
Old 05-21-2012, 06:22 PM
Tony
 
Join Date: Oct 2005
Location: Nevada City, Ca
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If you mill the heads you will also need to mill the intake manifold. As mentioned you may get into valve to piston issues. There would need to be a bit of R&D work as far as checking clearances, etc. I checked the manual and it shows a maximum of .5 mm (.019")material removal.
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1971 280SE/C 3.5 (5.6 iron block build in progress)
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  #32  
Old 05-21-2012, 11:45 PM
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Tony and Tomguy,
you are saying I'd run into trouble with these milled heads anyway in terms of geometries?
So the claim is that the original head cc-s at 52.5cc. Mine has 46cc.
this means a 1mm cut.
This would require a cut of the intake manifold of the same amount each side. Is it standard procedure to cut both head and manifold?

This comes on top of the trouble with the power loss through reducing Compression rate from 9.5 to 8.5.

I am really lost.

Would you try and find a local shop to repair the existing heads? Or would you install these 117 heads?
Best, Martin
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  #33  
Old 05-22-2012, 08:03 AM
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Location: Luzerne County, PA
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I assume you have loose and/or broken guides on your 3.5 heads. Pressing in guides should be easy, it'd be reworking the seats/valves that I'd wait for a US shop to do. How do the seats look currently? I'd say if they aren't scorched, that new guides may solve your issue. I would need to see the fit of the 4.5 heads on your engine, the way the intake manifold looks, and I'd probably put one the heads on with your previous head gaskets as a "Test fit" to check valve/piston clearance with some plumber's putty on the valves to measure the thickness of it afterwards to see how close they get to the pistons.
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  #34  
Old 05-22-2012, 10:57 AM
Tony
 
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Martin,
Guides come in a "repair size" with a larger OD. Have you checked into those? There is not much that can't be repaired on a head.
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1971 280SE/C 3.5 (5.6 iron block build in progress)
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  #35  
Old 05-22-2012, 12:23 PM
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Quote:
Originally Posted by Tomguy View Post
I assume you have loose and/or broken guides on your 3.5 heads. Pressing in guides should be easy, it'd be reworking the seats/valves that I'd wait for a US shop to do. How do the seats look currently? I'd say if they aren't scorched, that new guides may solve your issue. I would need to see the fit of the 4.5 heads on your engine, the way the intake manifold looks, and I'd probably put one the heads on with your previous head gaskets as a "Test fit" to check valve/piston clearance with some plumber's putty on the valves to measure the thickness of it afterwards to see how close they get to the pistons.
Thanks Tomguy

If I understand correctly you are recommending continuing with the existing 116 heads and leave the 117 head alone.
This is possible. Only thing is.. I am in Oman and have no clue how to find a shop I can trust to repair the head. I think the shop needs to set the correct size bore for the new oversize guides.
I believe the valve seats might be ok. But two guides came loose at cylinder 7 and 8.
The compression rates were also not great but I missed depressing the gas pedal during compression test. I believe piston rings are good.
Martin
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  #36  
Old 05-22-2012, 12:28 PM
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Quote:
Originally Posted by Tony H View Post
Martin,
Guides come in a "repair size" with a larger OD. Have you checked into those? There is not much that can't be repaired on a head.
Hi Tony,

thanks. What is the exact procedure to repair the old 116 heads?
But a set of repair size guides. Take heads off. Bring to a shop which a mill and correct (adjustable?) reamer, then press the new guides in and done?
Or is the process to put new seats in at the same time?
Can every shop do this or not? Is a shop doing a pressure test after the job?
Want are the standards and specs?
Martin
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  #37  
Old 05-22-2012, 01:59 PM
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Martin,
Let the seats be for now unless they're burned. Bad compression numbers caused by valves not seating are often caused by bad guides. With new straight guides your valves and seats will seal better and if they're a bit off they'll wear back together to seal better in time.

There are different valve guides available from OEM size to 1st & 2nd oversize. I got an OEM & a 1st oversize for my 117 heads - one came loose. The 1st oversize was too big. Depending how long your guide has been loose either OEM or 1st oversize are your best bet. A little reaming for 1st oversize, but OEM may be a tight press fit still.

Standard:
Pelican Parts - Product Information: 116-050-41-24-M105
Pelican Parts - Product Information: 116-050-47-24-M105
1st OS:
Pelican Parts - Product Information: 116-050-49-24-M105
You may need to call for exhaust 1st OS.
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  #38  
Old 05-22-2012, 02:16 PM
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Hi Tomguy

Your repair: One guide came lose after the repair? Or before?
Question: Can I do this job ..changing guides by myself? And what tools do I need to do this?
I guess I'd need a press? and a reamer?
For the two guides which came lose in my head I would need the first oversize (plus 0.2mm) but for all the others that are tight now....would you recommend the OEM (standard) size?
How would you tackle this challenge in the dessert?
Martin
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  #39  
Old 05-22-2012, 05:44 PM
Tony
 
Join Date: Oct 2005
Location: Nevada City, Ca
Posts: 690
Martin,
Installing valve guides is basic machine shop work-any qualified shop should be able to do it. it is not something you could do yourseld. Once installed the guide needs to be honed to the proper ID with respect to the valve seat-so the valve will seat correctly and not at a angle to the seat. There is no way one could do that their self. But as I said it is basic machine shop work. Oversizeds guides are install frequently-i'm sure even there.
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Last edited by Tony H; 05-22-2012 at 06:43 PM.
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  #40  
Old 05-23-2012, 08:38 AM
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Tony, if you were me would you buy the new guides and bring the shop new guides and the heads and they deal with it....that's it?
What guides would you use/buy?
For the guides that seem to be tight and original...would you use OEM size
For the 2 loose valves would you use 1st oversize guides?
Martin
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  #41  
Old 05-23-2012, 10:03 AM
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I suspect that a machine shop in Oman will be able to do this for you pretty easily. I lived in Jordan for a year about 20 years ago and it was very easy to keep a 40 year old Mercedes on the road back then.

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  #42  
Old 05-23-2012, 11:19 AM
Tony
 
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Location: Nevada City, Ca
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Hi Martin,
Considering the work to remove/install the heads and the fact that the guides are not very expensive + the ones that are not loose are probably worn out I would replace them all. Valve guides are pretty simple so aftermarket ones are probably fine but I have no expierence in that area. I would buy the parts and bring them in to the shop. sometimes they will not warrenty work done when they don't supply the parts but they usually have a huge parts markup.
Quote:
Originally Posted by werminghausen View Post
Tony, if you were me would you buy the new guides and bring the shop new guides and the heads and they deal with it....that's it?
What guides would you use/buy?
For the guides that seem to be tight and original...would you use OEM size
For the 2 loose valves would you use 1st oversize guides?
Martin
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Tony H
1971 280SE/C 3.5 (5.6 iron block build in progress)
European Version
Sunroof/Manual Trans
A/C P/W
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  #43  
Old 05-23-2012, 11:39 AM
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Join Date: May 2006
Location: Boston
Posts: 1,157
Thanks Tony,

What would be on the shopping list?
8 Standard size intake, 8 exhaust guides except for the loose guides?
There seem to be no 1st oversize exhaust guides available?

or would you just buy 2 sets one standard and one oversize and then the machine shop can pick and choose?
Martin



1)Valve Guide Exhaust Standard 15 X 11 X 49 mm (8 Per Car) 300SEL 3.5 M116.981-

2) Valve Guide Intake Standard 14 X 9 X 47.5 mm (8 Per Car)300SEL 3.5 M116.981-

3)Valve Guide Intake 1st Oversize 14.2 X 9 X 47.5 mm (8 Per Car), 300SEL 3.5 M116.981-
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Old 05-23-2012, 11:39 AM
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