280SL European engine

[declanobrien]

I am restoring my European 1970 280SL, and am rebuilding the engine at present. Have checked the head thickness which is approx 83.5mm, after it has just been skimmed and valves ground etc, and based on the forum understand it is now scrap. I have now sourced a 280 SE head and block. The SE head ref is 130 016 1101 which is the same as my original SL head. The SE head is original, unskimmed. The SE block however is beyond repair, and I am hoping to use my existing SL block. The cam on my existing head is an "02" cam, but has significant corrosion on the lobes. The cam on the SE head is an "08" cam and is in good order. Can I use the "08" cam (with the SE head) on the SL block, or will I be in trouble with the injector pump as the threads on the forum seem to suggest?  Can I use the "02" cam and pedestals on the SE head, or alternatively purchase a new "02" cam if the existing one is beyond repair? I am not worried about loss of performance in using the "08" cam. Also, how critical is the Min thickness of the Block, as I think I am now close to Min on my SL block.
Any advice appreciated.

[Benz Dr.]

Minimum thickness is 85.00 mm from what I recall so you should be OK with your original head.

[declanobrien]

Thanks for reply.
I am still unsure about my Camshaft issue.
Anybody know if I can use an "08" camshaft and pedestals on an SE head on a European SL 280 block (1970) or will I have a problem with the injector pump?
I am really stuck at the moment.
Declan

[ja17]

Hello,

Some of the later version camshafts had larger diameter main journals.  Any combination will work as long as you use the correct internal diameter cam stands with the same duameter camshaft. You will have no issues with the IP.

The minimum head width is 84mm. The problem with a over milled head is  more material is taken off the ends  than the center since the head actually "arches" in the center when it is warped. (Each end of the head remains lower than the center).  Cutting the head flat again removes a lot of material off the cylinders on each end, significantly raising the compression on these end cylinders only. I have seen overmilled heads cause  210 psi compression on the end cylinders and 160 psi compression on the center cylinders !  Getting an engine with this compression to idle smoothly and not "ping" is nearly impossible.

In addition the top deck of the  head can accomodate only so much warp before the camshaft binds or the valve cover fails to seal at the ends.

[Benz Dr.]

That's right - it's 84.00 mm.  I think they're about 85.00 when new.

We used to plane heads years ago and we still do but we straighten them first now. This means both sides of the head end up getting machined but then everything is flat. This is a lot more work since all the valve guides need to be removed so it's usually part of a head rebuild.
Measuring the head thickness is a bit of a challenge after this but I can tell if both sides have been cut. Cam shims are a must after after this procedure.

[declanobrien]

Many thanks. This is very helpful. I will probably now use my SE cam and pedestals with my SL head. I spoke to my local machinist, who comes very highly recommended. He has suggested that I give my overskimmed head a try. He also suggests shaving approx 15 thou off my 87.5 pistons, to help lower the Compression ratio, and also to help valve to piston clearance. I know I am pushing limits, but maybe it's worth a try.

[ja17]

Hello Brian,

If the compression in the cylinders is uneven (more than 20% variation) due to variation in combustion chamber volume (end combustion chambers tend to loose more volume when the head is milled), you will never get the engine to run smoothly. Mic the end dimension  of the head and the center of the head to see if this is the case. If the deviation is not too great you may be ok.