W126 500sel 560 head swap?
 

Guys, as some of u already know, i have a w126 500sel 1984 euro spec with the CSI old one ie not the ke sys. now i am considering swapping in a 560 full head.
how possible will that be, i am looking for a simple job with minimal mods? i dont even want to cgange to the newer csi sys.
your thoughts are highly appreciated. Will it give me more top end? cause this 500 is good low down but seems like strangled above 5000 rpms.

What does the 560 head offer that will increase your performance?

Tom W

i think it should have larger valves with matching ports and a more agressive cam

The real issue is the combustion chamber size, measured in cc's. If the 560 head has a larger combustion chamber the compression ratio will drop and so will performance. This is true even if the 560 head has larger valves. Speaking from experience, larger valves and a better camshaft alone will not increase performance. If anything, larger valves will kill the low end. What you call strangled at 5000+ rpm, is due to the hydraulic lifters used in all MB V8's after the mid '70s limiting the rpm. The early, mechanical lifter V8's would rev easily to 6500 rpm. Back in the day, a euro spec 500 was the model to have. IMHO, a euro spec 500 M117 gives about the same performance as a U.S. spec 560 M117 motor. After all, the 560 was Stuttgart's answer to all the grey market 500's that were imported during the early '80s.

well i can go for a full 560 euro spec engine, i think those where rated at around 300 hp flywheel, but mine is already rated at 260hp and the change to the newer ignition/injection sys will be too much trouble.
so any advise regarding the lifters??? can anything be done to release more free reving at the top??

You can use the euro 560 engine with the old K jet CIS system and the older style ignition that you already have.... It all swaps over.
I did exactly this when putting a euro 560 engine into my 85 euro 500 SEL.

I dont think the 5.0 was rated at 260 hp in 1984 though, more like 240 or so if I remember correctly.

I'd do the swap, I beleive combustion chamber size is the same and the increased valve size was the same thing AMG did for their 500's when they did head work.

Of course, you could CC them easy enough to be Sure on the comb. chamber size.

A euro ECE cam will also wake the engine up Nicely...Or, we have AMG spec cams available should you be interested.

Jonathan

those amg cams sound tempting:) so would i need new valve springs with those???? and do they fit any model w126 500?? mine is 1983 1984 mod and with no cats since its the older cis system.:)

Jay,

We could do a set for the Euro 500. You would need to measure/set your own lash as well.

Fresh valve springs are Never a bad idea..how many miles on your engine?

Jonathan

Jonathan,

To be honest i dunno exactly how many miles on the engine cause we just recently got the car and unfortunately the odometer is stuck on 43000miles.
But i can tell u the engine is sweet, with almost no oil consumption and all the seals seem fine with no oil smudging.
any ways before we delve deeper into this, how much will those set me?

This is an old but good string. The only thing I would add is the revving ability of those that have used a more updated fuel management system. One person on benzworld has used a variation of the megasquirt. He attached GM parts to facilitate his modifications and reports of improved throttle response, fuel economy and revving. My '85 380SL Megasquirt Project Progress - Mercedes-Benz Forum

It's true that there are some valid reasons for switching to a Megasquirt set-up, but increasing an engine's rev-ability isn't one of them. CIS-E systems can rev just fine. Just look at the original 3.0 M104: it had a 7,000 RPM redline! The original Hammer also ran a CIS-E system with the same M117 bottom end. I suspect the 2 valve M117's lack of top-end was due to the valve train and/or too conservative cam timing. We all also have to remember that the O.P., my good friend Jay Rash, loves to rev the pee out of everything. He even retarded the cam on his M103 to get more top-end! This is an engine that already had a 6,200 RPM redline!

The two valve heads on M117s just don't seem to breath well at high RPM. Larger valves might help, but I would not expect it to make a big difference. If your engine has the log manifolds, then consider the tri-Y exhaust manifolds. They should bolt up to any M117 and would really help that engine breath.