Cyliner heads on '73 M117
 

Due to a suspected bent valve situation I'll be checking the yards this weekend for a suitable set of rebuildable cylinder heads. How many variations do I have to choose from? I'll likely stick with a pair from a W108 or W116 w/o air injection, not too many differences there I hope. Also, what is the best source for the specialized hex drivers I'll need to deal with the head bolts?

Getting the heads off is easy w/o the wierd wrenches. You need an 8mm allen key in sockets and a universal joint. Having the two specialed wrenches is essential for reassembly.

You need the EFI heads. It won't matter if it's a 280se 4.5 or a 450se or a 450sl. Tomguy suggests a set of 3.5 heads as a compression upgrade.

I use Baum tools for my specialized tools, but there are less expensive places to buy them.

Aside from the wrenches, don't forget a 24mm wrench for the bolt on the cam and a gear puller. Also you need the pin extractor for the guide rails.

That or bring a means of cutting the timing chain. One easy technique, if the engine turns, is to look for a master link pin and remove it.

-CTH

I've got a M117 parts motor out of a 72 280SE 4.5. Heads are $50 each plus shipping.

I've had good luck with Samstagsales.com. http://www.samstagsales.com/mercedes.htm#engine

As the dollar looses ground to the Euro prices are getting steep.....

In theory, any m116/m117 heads from a cast block will work. From what I've heard from a mechanic (not sure about this one) you can use K-Jet heads on a D-Jet engine and vice-versa. But I would personally suggest, as CTH says, 3.5 D-jet heads (from a 111, 108, 109, 107 or 116 - they'll all work).

Yeah, this morning I figured out that the special tools are not necessary to get the heads off. Right now there's a CIS 4.5 and a later 5.0L M117 in my yard of choice. So there is a definite difference between the EFI and later CIS heads? It would seem typical of Mercedes to have a differently machined head due to injector type. Though I'd prefer to get another set of heads I could swap with mine couldn't I also just harvest the unbent valves from the junkyard heads? Would a piston/valve collision cause other damage to the head castings or guides?

Note how I said "from a cast block"! The aluminum block m116 and m117s have different bolt patterns for the heads - otherwise, 420 heads would probably make one hell of an upgrade for 4.5s (better combustion chambers, better flow, higher compression). Also, not all m116s and m117s had the same valves for heads. I need to double-check, but I think only intakes from a 5.0 would be interchangeable (if at all).

There's a head gasket change for the non-hydraulic lifter heads to hydraulic, isn't there? That's usually a really good sign to be VERY careful on an interchange.

-CTH

If there is, CTH, then the ones on FastLane must be for the hydraulic heads, and work for the ones with manual as well - because the same part shows for a 1972 4.5, and a 1978 450SEL.

on a diesel if you have a piston hit valves they break the cam.

i don't know about a v8.

i would have a good machinist look at it and install the valves. you will want to grind them anyway while it is apart.

tom w