Learned something today

[john.mancini]

Today I learned something that I bet a lot of you already knew. My 230SL had a 129 block replacement early in its life. I sent the 129 replacement block off to Metric Motors, (those guys are great!), two weeks ago. I had talked to a couple of 113 guys who told me, "All 129 blocks are 250SL blocks". Made sense to me. Anyway, talking to Mike at Metric Motors today he told me I had a 230SL block, even though it has a 129 casting number. Because....... it has the four main crankshaft. Here is the question I am posing to my fellow Pagoda owners:  At this stage, with the engine out of a spectacular, perfect body, west coast, super clean 230SL, do I put the 129 block back in, or have Metric Motors swap for a 127 block and have it re-stamped with the original engine number?

[Pawel66]

Casting numbers do not matter. I would keep what you originally had.

[dirkbalter]

John,
I had exactly the same. My 127 was changed to a 129 in its earlier days. Originally, I was going to go back to a 127 motor to create a "numbers matching " car. I was told by several people including Mike at Metric that the 129 is probably the best motor, a bit stronger than the 127 due to the crank bearings but not as heat sensitive as the 130. I chose to keep the 129. I also chose to match the motor number to my data card but with a 129 at the beginning.   
(For me, I want to drive to car, not interested in hauling it to shows for evaluation by "experts")
A lot of the guys will disagree with me and that's ok.

[Cees Klumper]

I would keep the current engine, and for sure would not recommend stamping in an incorrect engine number to make it appear as if it is the original engine.

[john.mancini]

John,
I had exactly the same. My 127 was changed to a 129 in its earlier days. Originally, I was going to go back to a 127 motor to create a "numbers matching " car. I was told by several people including Mike at Metric that the 129 is probably the best motor, a bit stronger than the 127 due to the crank bearings but not as heat sensitive as the 130. I chose to keep the 129. I also chose to match the motor number to my data card but with a 129 at the beginning.   
(For me, I want to drive to car, not interested in hauling it to shows for evaluation by "experts")
A lot of the guys will disagree with me and that's ok.

Dirk, according to Metric Motors, this particular 129 engine has the same # of main bearings (4) as the original 127 did. Why would it make this 129 better? As this plays out, what I am understanding, (I think), is that MB replaced certain 230SL 127 engines with 129 engines that were also 4 main bearing engines. Those 129's that went into 250SL's from the factory were not 4 main bearing engines. Does this sound correct?

[dirkbalter]

John, I apologize. I should have red your post more careful, instead I missed your point.
As you said, it would not make it better.

[Benz Dr.]

All 129 engines have 7 main bearings. The 129 is a nice compromise between the 127 and the 130. Very good power and still not as thirsty as a 130. They also are not prone to running hot because they have the largest radiator of the three 113 variants. They also have an effective oil cooler.

[john.mancini]

All 129 engines have 7 main bearings. The 129 is a nice compromise between the 127 and the 130. Very good power and still not as thirsty as a 130. They also are not prone to running hot because they have the largest radiator of the three 113 variants. They also have an effective oil cooler.

Dan, I'll need to talk to Mike at Metric Motors again. He claims that they have seen some early 129 replacement blocks used on 230SL's with 4 main bearings. I'm confused. I'd much rather keep the 129 block if it does indeed have the 7 main bearings.

[MikeSimon]

I am not sure about the "129 replacement blocks with 4 mains".
What constitutes a "129"?
Mainly the displacement and the 7 main block.
If it is a 4 main and 2.3L it is a 127.

[john.mancini]

I am not sure about the "129 replacement blocks with 4 mains".
What constitutes a "129"?
Mainly the displacement and the 7 main block.
If it is a 4 main and 2.3L it is a 127.

Mike at Metric Motors got a "kick" out that quote. He sent me a video and a picture of a 129 casting block with, as you can see, only 4 main bearings. He said, over the years, he has seen and rebuilt many MB 129 blocks with only 4 main bearings. Many were early replacement blocks on 230SL's. Hope this picture comes through.

[114015]

Mike at Metric Motors got a "kick" out that quote. He sent me a video and a picture of a 129 casting block with, as you can see, only 4 main bearings. He said, over the years, he has seen and rebuilt many MB 129 blocks with only 4 main bearings. Many were early replacement blocks on 230SL's. Hope this picture comes through.

John,

Yes, very normal.
What you see (is what you get) - only a casting number - and that does not tell you much - per se.

What U have is a 230 SL M127II block and not a M129 block, because of the only four main bearings. If you had seven - it would be a 250 block ...
(as you know .... both have the same bore).

Early 230 -M127II blocks had a 127 casting number,
later on, when the 250ies were introduced (in August 1965), they changed the casting molds. Don't know exactly as to when they did that but "late" 230 blocks just have the 129 casting number.
Consider please, a casting number is not an official parts number but only a (factory-) internal (parts) number...;
the same basic tool (molds) were used by then to make 230 and/or 250 blocks, at least the outer halves.
It's just that....

My (brand new) replacement block also carries the 129 011 number shown on your pics....

Achim

[john.mancini]

Thanks Achim. That's basically what Metric Motors confirmed. Like I said, I did not know that. I learned something new.

[MikeSimon]

A casting is relatively easy to modify, depending on the casting process. You take a core out or add one in and you have a different part. This way, one basic mold can be used to make parts that are different in minor details.

[john.mancini]

Understood, but the basic point was, not all 129 blocks have 7 main bearings. I thought they all did.

[cydways]

Is it just an unknown if a 129 block is a 4 or 7 bearing until you open it up or is there a date range that these exist? I have a factory replacement block in my Jan. build '66 230sl with 127 stamped on the pad (no serial number) but it has the 1290110001 block.

[Benz Dr.]

I can't say for sure, but maybe look at the end of the crank. 250 and 230 cranks are quite different in appearance as far as drive pulleys go. I was fortunate in that I had a 250SE block in my car when I bought it. Oddly, it still had the 230SL flywheel and pressure plate. I changed all of that when I rebuilt the engine.

[stickandrudderman]

M127 is an M127, period.
M129 is an M129, period.
Casting numbers are irrelevant. Where engines are concerned, the only number that matters is the number STAMPED NOT CAST in the engine block on the machined flat surface area at the left side rear where there is normally a riveted metal badge too (but not always).

[Shvegel]

As Mike Simon says it is not a big mystery.  Mercedes ran out of 127 blocks so they cast new ones using the 129 architecture and the casting cores from the 127 lower creating a stronger 230 block with 4 main bearings.  All fairly simple when you are sand casting.   When the Chrysler 426 Hemi went racing with NASCAR they had some failures during testing.  The engineers went to the foundry at night and simply shaved sand off the casting cores where they needed more strength in the castings and cast new blocks. Problem solved.

[mdsalemi]

Mike at Metric Motors got a "kick" out that quote. He sent me a video and a picture of a 129 casting block with, as you can see, only 4 main bearings. He said, over the years, he has seen and rebuilt many MB 129 blocks with only 4 main bearings. Many were early replacement blocks on 230SL's. Hope this picture comes through.

My only addition to this thread is validation of the fact that Mike Elias at Metric Motors knows exactly what he's doing. They have seen so many MB engines and blocks go through their shop in the past decades...

[MikeSimon]

I think the consensus is, that the casting number on the block DOES NOT determine what engine type it is. When one needs parts for the engine, one does not use the block casting number to identify the engine.

[john.mancini]

I was surprised to see this thread breathing new life, but, my original point was, that I learned from Mike at Metric Motors that not all 129 blocks have 7 main bearings. Some have 4, just like the 127 blocks. It had NOTHING to do with engine stamping ID numbers, it was about casting numbers!