Hello Guys,
There are four common types of 113 heads. The 230-SL, 250-SL. early 280-SL, and late 280-SL. The 230-SL and 250-SL are interchangeble as stated. The others cannot be switched. And the 230/250 heads cannot be used on any 280 or visa versa.
The 230-Sl head is unique to that W113 model (not used on any sedan engines). The 250-SL, 280-SL (early) and 280-SL (late) heads can be found on their respective 250-SE, 280-SE sedans, coupes and convertibles of that era.
The 250SL/SE head when used on a 230-SL engine will enhance performance slightly with it's larger valves. The design of the 250 head is a little more modern and has features not found on some of the 230-SL heads such as valve rotators, larger valves, newer design of the valve guides and seals.
There were minor design changes during the run of each of these series so head casting numbers may vary from year to year. For instance there may be three or four different head numbers in the 230-SL series all which are interchangable.
The 230-SL head I have has no model designation cast into it just the head #127 016 1901 with 9.3:1 compression. This number is located between the 2nd and 3rd spark plug. The year of manufacture is "65" cast into the top deck of the head.
The 250-SL, SE head I have is identified "250" with #129 016 0301 with 9.5:1 compression. The year of manufacture is "66" also cast into top deck of head.
The early 280-SL head I have is identified as "280" with #130 016 0701 with 9.5:1 compression ratio. The year of manufacture is no longer cast in the top deck.
The late 280-SL head I have is identified as "280-SE/A" with #130 016 0801 also with 9.5:1 compression. I have heard that the "A" in this designation signifies that it was for USA delivery cars?
There are some other less common variations like the low compression engines, used mainly in underdeveloped countries.
In addition these cast numbers on the heads may vary slightly from minor changes in design during production. For example; I also have an earlier 230-SL head "64" #127 010 4220 also with 9.3:1 compression. This "64" 230-SL head number is different from the 230-SL head listed above. This was a result of minor design changes during the series. These heads are interchangeable and are basically the same as all other 230-SL heads. I believe there are one or two other numbers within this group as well.
For interchanging, think of three posssible head types first: the 230-SL, 250-SL(interchangeble), second: the early 280-SL, and third: the late 280-SL. These three are unique and must be kept with their engine blocks.
Ben,
The twincam engine M110 had a block remarkably close to the M130(late). I am not sure if it could be used in place of a late M130 block? I believe the crankshaft may be the same.
These M110 (twincam) engines were supposed to be much improved over the M130 (280-SL) with it's cross-flow hemisperical combustion chambers and twin camshafts. In reality only a small amount of horsepower was gained and the M110 engine ended up being extremely heavy and complex in comparison to the earlier six.
The result was little or no noticable improvement in performance over the european delivery M130 (280-SL) engine. Mercedes quickly reverted back to a single camshft simpler, lighter and more efficient engine (M103) in the later 300E series W124 chasis cars.
1975 was the year of ruination for most Mercedes gasoline engines in the USA. Compression ratio had already droped from 9.5:1 to around 8:1 in 1973. The addition Catalytic comverters in 1975 along with a mess of emission devices really bogged down these engines. Steer clear of 1975 gasoline USA delivery Mercedes whenever possible. The horsepower of an emmision 1975 450-SL was only 175 hp! These changes became more integrated and less troublesome in later years after 1975 and horsepower slowly crept back up as time went on and emission designs improved. The high compression, emission device free european delivery engines of 1975 era were noticably more powerful and less troublesome than the USA conterparts.
Joe Alexander
Blacklick, Ohio