head swap

[graphic66]

I would like to take a head from a 67 250SL and put it on a 66 230SL. Would this work and what would the results be? Which cam should I use if this is possible. Also would my manifolds be the same. The reason for this would be that I have a spare 250 head and I could have that head rebuilt then do the switch with a minimum of downtime. My current head has corroded through and has a small but manageable leak on the left side in the middle. The car was neglected for many years. If this is possible it would be a plus. I used prestone super seal in the radiator and it has sealed the leak however I would like to have a fresh head and valves. Any help would be greatly appreciated. Thank you

[Cees Klumper]

I don't think the 230 and 250 SL heads are interchangeable but I will doublecheck later today. The 230 SL heads are relatively rare. What would be an option is to swap out the entire engine. You could even put in a 280 SE/SL engine. Are you sure the head is corroded all the way through but still functions?

white 1969 280 SL

[Naj ✝︎]

graphic66
The 250 head WILL fit the 230 engine.The inlet valves on the 250 are bigger and the valve guides more substantial. I used the '084' camshaft which came out of the 230 because it was sportier than the '086' on the 250 se head that I used.
I had the earlier 230sl 'three into one' exhaust manifolds and I reused them.
I believe the injectors on the 230/250 are the same as well.
Its a straight one for one swap.
If you have further questions, I'd be happy to answer.
good luck
naj

naj
hobel 65 230SL
jalopyno 68 280SL

[Cees Klumper]

Thanks for setting me straight Naj, sorry about that. I read up on this now and apparently the compression of the 250 head is higher (9.5 vs 9.3 on the 230SL head). I don't know whether this is problematic for the engine block itself, which in the 230 SL has 4 main bearings as compared to the 250 and 280 which have 7 main bearings. Anyway, since you did the swap on your engine, I am sure you considered this beforehand.

white 1969 280 SL

[ja17]

The swap as naj mentioned is a straight forward job. The original 230-SL cam is a little hotter. I believe there is an early and late 250 series head. The early heads had the 14mm ball stud valve adjustments with the skinny rocker arms as on the 230-SL. The later 250-SL head had the 17mm ball stud valve adjustments with wider rocker arms and wider lobes on the camshafts. Just check the size of the valve adjusters to see which one you have. By the way the 250-SE and 280-SL sedan heads are the same. If you have several camshafts just tell me what the ID number is on the cam and I will let you know which is best to use. The manifolds will exchange. The early 230-SL with steel headers may use one different front pipe from the other 113's ? I am not sure of this (working from memory). Our list member with the 230-SL rallycar is using a 250 series head on his 113 also.

Joe Alexander
Blacklick, Ohio

[n/a]

Beware! Don't take for granted that similar heads will perfectly fit.
Years ago, when I had to repair my 280SE sedan engine, I got a spare engine from another 280SE sedan but the head wouldn't fit because they had different water ducts.

Duro
Italy

[ja17]

Yes Duro,
The M130 engine series (280-SL, SE, SEL Mercedes) had a major engine re-design in 1969. The engine and blocks and heads will not interchange with each other. They must stay with their respective blocks or heads. The production break point for the 280-SL was chasis #...013 615. and #...040 705 for the SE sedan. The early 280-SL,SE heads had a squarer shaped combustion chamber. The later heads had a more oval shape. Thus head gaskets had a distinctly square or oval shaped combustion chamber shape depending on the version. Addition of coolant passages in the block and head dictated these changes. If you wish to research these changes in more detail review section 01-9 through 01-11/5 in the Big Blue Book.
One way to easily identify an early a late 280 SL or SE series engine is to look for the aluminum pod attached to the head near the injection pump. This pod holds the temperture guage sender, the temperature switch, and a coolant tube. On the later series 280-SL, SE engines this "pod" dissapeared.
The entire series of the 230-SL, 250-SL engines used heads which are slightly different but are all interchangeable. Some additional differences occure in the cams, rocker arms, adjusters etc. in the latest 250-SL, SE engines, however these changes do not prevent intechanging in these engines.


Joe Alexander
Blacklick, Ohio

[Benz Dr.]

Sorry to be jumping in on this one so late.
 The 230 and 250 heads are interchangable but not to the 280SL. There are 2 different heads and engines used on the 280SL. To my knowledge there's only one 129 engine and one 127. - I'll need to study this .
 The cams for 230SL ( there's 2 different ones , small difference really) will fit all engines except the late 280SL and IS the hottest cam next to the euro 280. The 230 cam can be made to preform the same way as the euro 280SL cam if you know how to do it. The 250S, 230S, 250SE,280SE,280SL ( early) all seem to use the same cam.
 The valve cones are all the same size but the guides are different . The 230 has a square keeper and the 250 and 280 have round ones. You can use 280SL valves in a 230 but the exhaust guides  ( only)need to be changed to the later style. I think the 230SL has it's own special retainer which if lost are very exspensive so I changed to 280SL style of which parts are plentyful.

Hop this hepls,
Dan c

Daniel G Caron

[ja17]

Hello,
I believe that the exhaust valves in the 250 series heads are larger than in the 230-SL. The 250 SE series head should perform a little better and have some of the later improvements as Dan mentioned. The 250 SE head will switch easily to a 230-SL. The 230-SL camshaft would be slightly hotter than the 250-SE series cams.

Joe Alexander
Blacklick, Ohio

[graphic66]

First I would like to thank everyone here, as with all of your input these cars are a lot less mysterious and a lot more fun. Back to the head, assuming the 250 SL head will bolt up to my block, how about the manifolds? Will I be able to use my existing exhaust and intake. This project will begin at the end of this season as I plan to pull the engine as compression is low [#2 cyl. 100psi and the highest is 135psi] and when I squirt oil in the cylinders the numbers come up to over 150psi. This looks like rings and with only 58000 miles on the clock and a previous stuck open cold start valve it all adds up to piston wash and premature ring wear, so at that time it would be fun to have my 250Sl head rebuilt and then ring the motor and do whatever else shows wear over the winter. Ill keep everyone posted. Hey whats the worst I could end up with, 2 rebuilt heads, right? Again thank you all.

[Benz Dr.]

Hi all,
 just so we're all clear on this:
 the valve face and seat are the same size on all three models.
It's the valve stem and the exhaust valve that has a larger diameter on 250 and 280 Sl's
Dan c

  230SL cam is the way to go


Daniel G Caron

[ja17]

Hello graphic66,
Your manifolds will switch over fine to the 250 SE,SL head. If you have the early 230-SL with steel exhaust headers, then the front pipes on your exhaust will be different. The later 230-SL cars had the cast iron mainfolds and were the same on all the rest of 113 engines.

Joe Alexander
Blacklick, Ohio

[graphic66]

My 66 230SL has the header style pipes, not the cast iron ones. Does this mean I need different exhaust pipes from the header to the muffler?

[ja17]

Hello,
You will be fine, just use the original header type exhaust manifolds from the 230-SL, when you do the switch!


Joe Alexander
Blacklick, Ohio