1970 250C 2.8L performance?
 

If the mods feel this should be moved to Vintage, that is OK.

I have a 250C with a 2.8L that is in need of a teardown/rebuild. The oil pressure relief valve fell out and the engine lost oil pressure. It runs, but it knocks. Also, the dual Zeniths are shot, so I will need to do something about them.

My question is, since I am going to rebuild it, what kind of performance could I possibly get out of this engine? Is it worth doing a performance build? I love the car, and I love going fast, so why not do it with this car? It wasn't a real slouch before, even with the worn out carbs, it still cruised at 100 mph easily, and topped out at 120.

I feel horrible that this car has sat for years, and now that I have a job that allows a little money to be thrown at projects, I want to get this thing back on the road!

Here is what I have to work with:
http://i333.photobucket.com/albums/m...C/094793f1.jpg

Thank you! Now, if only I could drive it... ;)

You could drop in a more modern engine with some get up and go. Those old engines were great for durability but getting power out of one takes some doing. The intake and exhaust were very small and they were fairly low compression. I would say either stick with the stock setup or go with something else entirely for an engine. But if you want to get more power out of something, it must breath and or have higher compression.

Well, porting and high CR pistons would be options during the rebuild. Is there anybody that has done anything similar to an engine of this vintage? How much power are these blocks able to handle?

I had considered a different engine, but to keep the costs down, it probably wouldn't have been a Mercedes engine. I would prefer to keep the engine that is in it.

I thought I read somewhere that there is a different intake available that allows the use of a single bigger carb. That would make adjustment and tuning a little easier.

Off to google the M104. ;)

I guess I never updated my profile, but one thing to remember, I am in ND. Not exactly the hot bed for Mercedes parts. :D

EDIT: That is a little too new for me. I prefer carbs to computers. ;) I know that they can make good power, but I like something that I can easily work on myself.

No! :) Fuel injection is not for me. I will cut a hole in the floor and use my feet before I start adding computers and all sorts of electrical wizardry to my car! ;)

Does anybody know of a good performance resource for these older engines?

If you delete your posts, it just makes me look like the crazy guy talking to myself over here. ;)

I guess I will ask another question here. What are my options for performance tires in a 14" wheel size? nothing?

I would like to keep the factory look, but if I have to upgrade to larger wheels, I guess thats what I will have to do to get good performing tires.

I am using a computer right now, aren't I? ;)

I have no problems with computers, I just like to keep my cars simple. I don't see a problem with that. ;)

hmmmm, was wondering why you were answering yourself. Thought I'd have to measure you up for a straight jacket lol :D

Tyre question is a little awkward :o what exactly do you call 'performance'? 120mph may be your limit on stock 14" merc rims I would say.

This is a very clean car from the pics so modifying it would make sense only if you do it right = hard work & much mulla$........

The 280SL's used an injected version of the M130 engine and it made 170hp. I still own my 250CE which had the M114 2.5 liter injected engine which also made 170hp. I can tell you that this is pretty good power for these cars. I hit 115mph in that car and it felt as solid as a rock. Acceleration was also very good.

If you're going to rebuild it, I suggest looking into megasquirt and cross posting on the vintage forum. A couple of guys have fuel injected their cars using this system and are happy with the performance.

Yeah, I am a little crazy, but not "talking to myself" crazy... Yet...

I don't exactly know what kind of "performance" tire I would expect to find in a 14" wheel, but I thought it was worth asking. All I was able to find are just regular, cheap touring tires. I am hoping to wring a decent amount of power out of this engine, and just want tires that can handle it.

It is in pretty good shape, but not quite as clean as the picture makes it out to be. There is faded and cracked paint, but no rust or dents anywhere. What comes to your mind when you say "do it right"?


I have read about megasquirt, and know that it can help make good power. I am just not a fan of fuel injection and more electronics. To me, it is just more to go wrong. I prefer the simple approach. From what I have read, the 2.8L was the last, best version of this motor, so I figure it is a good starting point. However, I have much to learn.

I am not completely opposed to a turbo, but I have no idea how much this block is capable of handling.

I will cross post this over into Vintage, maybe they will have some more ideas. :)

I would upgrade to a 15" rim,then you can select better tires.

After looking for 14" tires for a while, it seems like that is the case. I would like to keep the factory look, though. Finding 15" steel wheels shouldn't be an issue, but are there 15" Mercedes wheel covers that look like the ones on my 14" wheels? Maybe a set of 15" alloys would work, too.

you be better of with alloy wheels.Ebay has lots of them used.By the way your car is sharp.
I too was afraid of computer controlled engines.But having used CNC lathes and Mills I now how to trick a computer.
Like most Old Cars at car shows have brand new covette engines in them.

It is not so much that I am afraid of them, I have a few newer vehicles that I drive. I just really enjoy working on vehicles myself, and it seems that with more computers, there becomes less that I can physically do on my own.

What kind of alloys do you have in mind? Do the bundt style wheels come in a 15" size?

EDIT: Nevermind, I just found out that the 15" do exist, but are extremely rare. I will look for some other Mercedes alloys, maybe off of a slightly newer car.