250 pistons in 230 engine?

[jpinet]

I'm rebuilding my '65 w113 engine which is already on its 3rd and last possible oversize. It needs to be sleeved as the cylinders are oval. I have an opportunity to buy a set of new 250 pistons. Since bore is the same, is there a reason not to use these pistons in a 230 engine? Would connecting rods work?
Also, I'm looking everywhere for the max. gap between a piston groove and a ring and can't find it.
Anybody has that figure? I think it's .004, but not sure.
Thanks!

[Dave H]

If its an early 230 the pins may be 24mm.
250 had 25mm pins.
Con rods may not fit.
I am rebuildind my 250 at the moment and have all the MB engine rebuild specs at home.
I will photograph them tonight when i get home from work and post them on here, about 6 pages.
Very usefull document.

[GGR]

If bore is the same, then stroke is different. Two ways of doing this: keep the piston pin where it is and go with shorter rods; or keep the same rods and have the piston pin sit higher. Try to compare part numbers. If con rods are the same, then chances are that pistons won't fit. And if pistons were interchangeable, chances are they would share the same part numbers. I do not have access to EPC right now so I can't check it myself.

[ja17]

Interesting, according to the Technical Data Book, most of the critical specs are the same (crankshaft bearing, diameters etc.). The distance from the center of the wrist pins to the center of the connecting rod big ends is also the same on the two engines. Not sure where the extra 6mm of stroke comes from. Must just be the longer throw on the crankpins. The blocks are the same height. The height of the pistons above the wrist pins must be slightly different? There are two different wrist pin diameters to deal with (early /late) on the 230 engine. I might have to dig up some old parts and compare.

Yes .004" is the typical ring groove clearance for for the piston rings. Also .004" per inch of cylinder diameter is the typical ring gap clearance.

[jpinet]

Interesting, according to the Technical Data Book, most of the critical specs are the same (crankshaft bearing, diameters etc.). The distance from the center of the wrist pins to the center of the connecting rod big ends is also the same on the two engines. Not sure where the extra 6mm of stroke comes from. Must just be the longer throw on the crankpins. The blocks are the same height. The height of the pistons above the wrist pins must be slightly different? There are two different wrist pin diameters to deal with (early /late) on the 230 engine. I might have to dig up some old parts and compare.

Yes .004" is the typical ring groove clearance for for the piston rings. Also .004" per inch of cylinder diameter is the typical ring gap clearance.

Hell Joe,

Thanks for looking this up. I have the 25mm wrist pins, so that would work. My concern is really using a 230 conrod with a 250 piston. Is the thickness at the wrist pin the same? Is there a difference in mounting? I think not, but without having both to compare, I'm unsure. The alternative in my case is to reuse my old pistons which are at 82.97 and still good, sleeve the cylinders and use new rings on the pistons. That would be the least expensive way to keep my block and have a good engine. What do you think? Given your experience and reputation, your opinion is worth gold to me as I'm undertaking this rebuild myself. I used to be a car mechanic in the late '70's and an engine is an engine, even though the MB require more precision when rebuilding.

[jpinet]

GGR and Dave,

thanks for your input!

[GGR]

If rod length and block height are the same then the pin must sit higher in the 250 pistons. If you fit them in the 230 motor they won't reach the top of the cylinders.

Ring grooves can wear so you need to check that if you want to reuse your 230 pistons.

[jpinet]

If rod length and block height are the same then the pin must sit higher in the 250 pistons. If you fit them in the 230 motor they won't reach the top of the cylinders.

Ring grooves can wear so you need to check that if you want to reuse your 230 pistons.

Well, I can always weld a layer of metal on top of the 250 pistons to make up for the difference...
But seriously, the longer stroke has to come from somewhere. You're probably right. Joe said he'll try to compare both to see where the difference in stroke comes from.
You suggestion to comapre part numbers is a good one. I'll look into this.
I'll also be measuring my grooves to make sure they are worn within specs: .004
JP

[GGR]

On the M117 V8 for example, the shift from 5L to 5.6L is due to a longer stroke provided by a different crankshaft. Bore and Rods are the same, so pistons are different: the pin is higher on the 5.6L pistons.

This may, or may not be the same on your engine, as Engineers go through some calgulations regarding stroke/rod length ratios. Sometimes piston pins can also be ex-centered while shifting from one displacement to another (like on the Citroen DS 23 and the CX 25 engines. Blocks are the same).

[Dave H]

Compression heights of the 2 pistons differ.
Thats is the height of the piston above the wristpin.
If you put a 250 piston (with a 48mm comp height) on your pin it would be 4mm lower at TDC than your current 230 piston which has a 52mm comp height.
There is a bit more to it than that but all in all a 250 piston is not the same as a 230 piston.

[jpinet]

Compression heights of the 2 pistons differ.
Thats is the height of the piston above the wristpin.
If you put a 250 piston (with a 48mm comp height) on your pin it would be 4mm lower at TDC than your current 230 piston which has a 52mm comp height.
There is a bit more to it than that but all in all a 250 piston is not the same as a 230 piston.

Dave,
thanks a lot for this specification. That answers my question!
Now, hopefully, my 230 pistons are still within spec and I'll have to sleeve the cylinders and change the rings to match that 83 mm oversize.

[Dave H]

The stroke also differs between 230 and 250.
72.8 mm v/s 78.8 mm for a 250.
This would suggest a differance in the crank .
The piston is lowered 3 to 4mm (51.6 or 52.2  v/s 48.6 ) but the stroke increased 6mm giving 3mm height back on the upstroke and 3mm further on the downstroke.
This gives the extra 20cc displacement for the same diameter .

The tech specs are on

http://s272261875.websitehome.co.uk/gal251981502/pdf/M180_rebuild_guide.pdf

If somebody could work out how to put these 12 pages in the tech manual it would be great .

[stickandrudderman]

That's a very usefull summary that I haven't seen before.

[jpinet]

The stroke also differs between 230 and 250.
72.8 mm v/s 78.8 mm for a 250.
This would suggest a differance in the crank .
The piston is lowered 3 to 4mm (51.6 or 52.2  v/s 48.6 ) but the stroke increased 6mm giving 3mm height back on the upstroke and 3mm further on the downstroke.
This gives the extra 20cc displacement for the same diameter .

The tech specs are on

http://s272261875.websitehome.co.uk/gal251981502/pdf/M180_rebuild_guide.pdf

If somebody could work out how to put these 12 pages in the tech manual it would be great .

Those tech specs are great!
Thanks for making them available!

[Garry]

Have inserted the specs as a link under Engines in Tech Manual

http://www.sl113.org/wiki/Engine/GeneralEngineSpecifications

Garry

[ja17]

Yes, excellent, quick and easy to use!

[Peter van Es]

I hate to be the bearer of bad tidings, but this is not how we should do this.

The pages are linked to from another website. Out of our control. If that website goes down, or is changed, the link is lost.

When we add a page, and add content,  first incorporating the standard text structure. All this is described in detail here: http://www.sl113.org/wiki/Main/News

Secondly the pages are marked clearly: Copyright 2003 Mitchell Repair Information. So the original website hosting this information is out of line, and so are we.

I have therefore removed that link from our Tech Manual. The only way you are allowed to put something with similar content up on our site is by re-editing and adding it as proper Wiki content on our site.

For all the content we have in the Wiki we have followed that process. That is why creating the Technical Manual is such a major effort, and is taking so long.

Peter

[stickandrudderman]

Lucky I downloaded and saved a copy!

[Garry]

Peter,

My understanding is that if I had copied it and then put it whole in the Tech Manual then I was breaching copyright.  By only putting a link I was not copying but just refering someone to another site.  I realised that under these rules we ran the risk of losing the info if the link was lost but at least we did not breach copyright??

In fact I thought if we post tech info by cut and past in total etc without the original ownesrs consent then we are in breach of copyright.

Maybe one of the legal members can elaborate.

[GGR]

They seem to be pages out of MB workshop document, judging by the presentation, style, font etc. Not sure what that copyright is about at the bottom of the pages.

[114015]

Lucky I downloaded and saved a copy!

Pfffff...., me too!

Gael,
Thanks a lot for your comments.
No, I think this repair information is not from the MB workshop manuals.
Some of the pics or drawings might be. Others (like the Haynes workshop manual) do use MB drawings (with their permission I'd guess)
but nevertheless, this repair information here seems to be Daimler-independent.

First of all, the BBB are separated in "passenger cars 1959 (- 1967)" and in "108 - 113". As such, there is no (clear) info overspanning W111 sedan engines (220b etc.) and the later 108 - 113's.
2nd) there is no summarizing repair/overhauling section for all the engine in one "article" but the info is separated in the different workshop groups (00, 01, 03, 05, etc.).

Nevertheless, a very usefull report.

Achim

[66andBlue]

...
The tech specs are on
http://s272261875.websitehome.co.uk/gal251981502/pdf/M180_rebuild_guide.pdf
If somebody could work out how to put these 12 pages in the tech manual it would be great .

Interesting copyright questions. The link provided by Dave H causes the downloading of 12 pages from a repair manual for which the Mitchell Company claims a copyright with the following restrictions: http://mitchell1.com/legal/legalNotice.html
"The materials published in this site ... and any other World Wide Web site owned, operated, licensed, or controlled by Mitchell Repair Information Company LLC, which does business as Mitchell1, or any of its related, affiliated or subsidiary companies (collectively the "Materials") may not be copied or distributed, or republished, uploaded, posted or transmitted in any way, without the prior written consent of Mitchell Repair Information Company LLC ... EXCEPT: you may download one copy of the Materials on one computer for use on that computer only, provided you do not delete or change any copyright, trademark or other proprietary notices, and provided you do not further copy or post the Materials on any network computer or distribute the Materials in any media."
Since Dave did not copy or post the material it does not appear that he violated any of the restrictions.
What he did, however, was exactly what the Mitchell Company also does:
"At certain places on this MRIC Internet site, live "links" to other Internet addresses can be accessed. Such external Internet addresses contain information created, published, maintained, or otherwise posted by organizations independent of MRIC. MRIC does not endorse, approve, certify, maintain, or control these external Internet addresses and does not guarantee the accuracy, completeness, efficacy, timeliness, or correct sequencing of information located at such addresses. MRIC provides the links only as a convenience. Use of any information obtained from such addresses is voluntary, and reliance on it should only be undertaken after an independent review of its accuracy, completeness, efficacy, and timeliness."
Thank you Dave for providing this convenient link and I promise that I shall download only one (1) copy and that I plan to not rely on the information without reviewing its accuracy!    

[Peter van Es]

In fact I thought if we post tech info by cut and past in total etc without the original ownesrs consent then we are in breach of copyright.

I did not say "cut" and "paste", I said re-editing. That means presenting the same content in a different style, order, make up, interpretation. I do agree with others though, that some of the content appears copied from Mercedes-Benz documentation (especially the pictures).

I left the link in Dave H's post… what  I was referring to is that the person who hosts …websitehome.co.uk is in breach of copyright. He is "posting" or "redistributing" content -- I presume without Mitchell's consent". If we were to link it in the Tech Manual, we'd do the same. In Dave H's message, I'm less concerned about it, because it clearly links to this external site.

Best would be:
a) find the location of the same document on Mitchell's website
b) ask their permission to copy it to our site

The second part, Alfred, refers to Mitchell posting external links. That's not applicable in this case.

Peter

[jpinet]

Guys,

I'm happy that my question about the possibility of fitting 250 pistons in a 230 engine brought up both a very useful document and a good conversation about getting needed and wanted information in our pages in an efficient and legal way.

I'm sure we'll find a way. Hey, if we can keep these great cars on the road, I have no doubt we can get this info!

Best regards,

JP