Thanks much for the info. I'm really hoping my crank is forged also. If it is, my plan is to increase the stroke to 86mm, via welding and offset grinding, and also narrow the journal width down to be able to use an off the shelf rod and bearings. I think it's possible to purchase pistons and rods with higher strength and each half the weight of stock.

And yes, I'm planning on the dbilas cams also.

What is your plan for the shape of the top of the piston and static compression?

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

I am using ROSS RACING pistons which will give about 10,5 compression ratio, though I do not agree in increasing the offset, rather lighten all the componets for more revs.I will be happy With 7000 rpm, also a big cost saving.I have included a Picture which I have borrowed from jezzma in finland as I am getting the same pistons he had developed, conrods are soon under Production.

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I have posted a Picture of the exhaust valves from m110 923 and a m110 989 showing the stem diameter, left side is the m110 921, stem size is 11mm (head diameter 37mm) , weighing in at 112 grams and the m110 989 With a stem diameter of 9mm and a head size of 39mm and weighing in at 104 grams.. sorry for all the confusion.

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Great to read some info on building up one of these engines, thanks for sharing.

My basis of wanting to increase the stroke, if it will actually be possible, is to increase displacement. Should put it just over 3 liters. This should not effect the revs, unless I'm missing something. Look at what the Honda guys do with the K20's. A K20 has a square bore/stroke of 86mm. With high revs they are getting over 200 HP out of them, and we have two more cylinders!

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

> wanting to increase the stroke, if it will actually be possible, is to increase displacement. Should put it just over 3 liters. This should not effect the revs,

A lnger stroke will increase piston speed, which will make the engine slighly less willing to rev, as with each revolution the piston will have to accelerate to a higher speed, which takes more energy. Whether you will be able to feel it or not is another matter.

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Csaba
1972 280SEL 4.5, silver

Thanks for commenting!

I'm a novice on engine design and theory. So take my comments as such.

True, a longer stroke will have a negative effect on a goal of maximum rpms. But with the increased displacement the engine will have to spin around 1000 rpms less to to achieve the same HP.

Since I plan on lightened rods, pistons, valve springs and retainers, and individual throttle bodies for induction, I feel I should overcome any negative of the increased stroke. ITB's have a tendency to hurt torque numbers. Longer strokes have a tendency to increase torque. Im hoping the pairing will somewhat overcome each negative.

But all theory at this point. The spring compressor arrived today so I can finally start getting the engine torn down and see what I have for a crank (forged or cast) and what clearance issues I'll have with increasing the stroke.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

With time and tools today I pulled out the rocker arms, pulled the cams, separated the cam box from the head, and then pulled the head. Pretty nasty looking. Obviously had some water sitting in it.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

The dome of the head is even deeper than I thought from looking at pics. Very little gap between the valves and the outer edge. Can't get much larger valves than what's there.

Tomorrow I'll separate the transmission and pull the oil pan and see what the bottom end looks like.

A visit to the machine shop is in my future. Along with shipping out the cams to dbilas.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

Built a box and have the cams ready to ship to dbilas.



The rest of the tear down set for tomorrow.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

It took me the whole day to tear down the rest of the engine. Good news is the engine is stock, stock bore, stock main bearing, and stock rod bearings.

The bearings look to have the wear expected of a mid mileage, good running engine.



I'm really excited about building this engine. The more I dig into it the more I like it. Duplex timing chain, main bearing caps with locating dowels between each rod, and the cast iron block is a heavy piece.

Good that I had my iPad available to reference "http://mb.bolinko.org" on some of the unusual (at least to me) ways in which items are mounted in the block.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

Here is a pic of the bearing caps at each location. It also looks like I have a forged crank! I'm far from an expert, but a cast crank would have a thin line of ground off metal at the form parting line. A forged crank has a wide line. See the red circle



I can still see the cross hatch pattern on the bores also. So minimum over bore required.

I hope to drop off the block and head to the machine shop this week, and ship out the crank to be welded/offset ground to 86 mm stroke. It looks like if I reduce the rod diameter a couple mm's I should have minimal work to the block and pan to eliminate any interference.

In increasing the stroke from 78.8mm to 86mm (7.2mm) the outside swing of the rod is increased half of that amount, 3.6mm. A quick measurement looks like I have around +5mm clearance. I have a little more research to do yet, but the stock rod journal is 48mm I can get bearing/rods for a 45mm journal. A 3mm difference. So half of that would be 1.5mm gain. So in theory the outside swing would increase 3.6mm - 1.5mm = 2.1 mm. So without any modifications the tolerance would drop from +5mm to +2.6mm.

I know, a lot of work/expense for a small amount of stroke increase. But since I want lighter rods and pistons, custom is already required.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

In researching for the rebuild of this engine it looks like the cam followers (rockers) and ball adjusters especially have limited availability. Took a bit of research and a few emails, but I found some. So I went ahead and ordered 12 of each.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

Due to the closeness of the bolts around each exhaust port it doesn't seem much can be had by fabricating custom headers. So I ordered a European set of stock exhaust manifolds. I will flex-hone and ceramic coat them. Hopefully with a good set of SS piping and flow through mufflers (no cats) and a crossover, I should be good.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

Sunday my wife and I took a drive up to the North Shore. They keep talking about the "Eddie" (major world known surfing event where the waves are over 50' tall), but still a no go. But was another chance to enjoy driving the Benz. It was a little overcast and spots of sprinkles, but the sun showed his face now and then and it was still in the mid 70's. On the way back we took the H1 (I know, hard to believe an island can have an interstate) and I pushed the car almost the whole way (can't post actual speed as I have heard that some have been cited for posting speeds above the speed limit) not that I actually drove faster than posted speeds (disclaimer). But the trip must have freed up the stuck rings as now the engine runs smoother and has noticeably more power. Gas mileage still sucks, this tank was 8.7mpg.



Today I met with the manager at Ted's Machine Shop, with the head and block, to discuss my build and what they can do for me. In a few days I should know the status of what I have and start the actual plan for the build.

They do not have the machinery/tooling to weld/off-set grind my crank, so I will be shipping that off to the mainland.

The oil pan was damaged, so one of those is on order, and I ordered a complete timing chain kit. Includes new tensioner and guides along with the chain, etc.

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"In wine there is wisdom, in beer there is strength, in water there is bacteria."

know the feeling, theses cars just love to run, I was on a Club tour where there was a stretch where i let it go for a bit..