m117 4.5 block measurement

[Tony H]

Got my 5.6 crank back from the machine shop after being cleaned, inspected and polished. Everything looks good on it-I guess I got a decent crank. Here it is in it's new home. Deceided not to bore for 5.6 pistons. It will cost alot more in machine work and custom head gaskets and I will not be able to get more than 9.25:1 CR even with 3.5 heads due to the huge dish in the 5.6 pistons. If I go with turned down 4.5 pistons using common 4.5 K-jet heads I will have a CR of about 10.5:1 due to the small remaining piston dish volume and I can dial in whatever squish clearance necesarry when I turn down the pistons. Here is a piston that is almost finished. When I get close I install the piston and measure the deck height and take off just enough to get about .040 squish. Still need to cut the valve reliefs. The block is going in next for cleaning, checking and honing. Not finding alot of options for piston rings. Goetze and Deves are the only brand that has listings for the 4.5 engine. My machine shop told me not to use Deves(I have heard it from others as well)

[mercmad6.3]

I wonder what the problem is with Deves rings? At the moment I am trying to find a supplier at a reasonable price, for a 250S with a .50 mm over bore. Mercedes no longer carries them in this size and when they did it was at a cost of $270USD per cylinder!!!.

[Tony H]

I don't know if they are just getting a bad rap or what. One forum refered to them as being made from cast iron sewer pipe! But they have listings for just everything in std. and oversize. I would really like to know if there is a problem with them.

Originally Posted by mercmad6.3

I wonder what the problem is with Deves rings? At the moment I am trying to find a supplier at a reasonable price, for a 250S with a .50 mm over bore. Mercedes no longer carries them in this size and when they did it was at a cost of $270USD per cylinder!!!.

[mercmad6.3]

The only problem I have with Deves is that they never answer emails....

[bwostosh]

Deves has been doing rings for a long time, just call and ask what material.
I use them.
True story, from a Cuban man, they did use cast iron sewer pipes to keep the old cars alive, the weirdest one was using detergent and water for brake fluid..

[Tony H]

Found these on ebay. might be less expesive to get another block and bore it for these pistons.
NEW MERCEDES 250 250S 250SE 250SL 1st OS 82.5mm PISTON SET PISTONS RINGS & PINS | eBay

Originally Posted by mercmad6.3

I wonder what the problem is with Deves rings? At the moment I am trying to find a supplier at a reasonable price, for a 250S with a .50 mm over bore. Mercedes no longer carries them in this size and when they did it was at a cost of $270USD per cylinder!!!.

[alfaking2000]

This thread covers exactly what I am considering for my 450SLC! great info on the piston compression height differences and what looks like a reasonable solution to the stroke/piston problem.
FWIW, my experience with Deves rings has been that they tend to wear the bores rather quickly if they are soft iron with a low nickel content. Deves rings are great if you are doing a low budget rebuild because they wear in quickly and seal uneven surfaces but what usually happens is the rings "machine the bores" to a certain extent, the extent being a .040-.060" overbore in some cases to remove the ridge.
I do not know how well they work in Mercedes engines. My experience is with Italian engines.
Hastings may offer a more moderate solution.