Cam Swap Advice Needed - M116 380SL
 

I'm usually on the diesel forum, but I have an gasser engine related question that needs the attention of the gearheads over here.

We have an '85 380SL with about 160k miles on it that is wearing its cams. It didn't help any that yours truly let them pit while changing the guides and chain about a year ago.

I have collected a number of replacement junkyard cams (and shims , rockers and compensators as well)

1. Replacement 380 cams (marked 62/63)
2. 420 cams (08/09)
3. 560 cams (26/27)

The prettiest of the lot by far are the 560 cams. The others are OK and should work, considering the age of the car and my efforts to keep it running using the correct oil.

Anyway, which cams would you guys choose? Will all of them work (even the 560s?)

This is SWMBOs grocery getter. We are not interested in any performance gains, just want to use the "best" cams understanding that there will be compromises and tradeoffs. I would not particularly care to have to start using premium fuel. We don't have hills here, nor is this car spending any time on highway on-ramps.

Your thoughts?

I should think that you may have to be guided by emissions testing.
The 62/63 cams have an extremely short intake profile (163deg. @ 2mm lift).
The 08/09 cams have a profile more in line with the rest of the US spec cams (179deg. @ 2mm), and would be my choice.
The 26/27 cams are unfamiliar; are they from a late 560? 1986/87 560s were fitted with 18/19 cams (187deg. @ 2mm), but with a late intake lobe center (120deg. ATDC) to reduce overlap and unburned HCs.

Frank-

Yes- they were from a late 560SE:

http://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Engine/107/M116_38/05-220.pdf

They are really nice looking whereas the others are so-so.

If I go with something non-380, I would assume I would need to adjust ignition timing?

There is no emissions testing where I am ( and never will be).

What might be the benefits/detriments of the 420 (or 560) cams

From the info page you provided, it would appear that the intake timing is the same for the 18/19 and for the 26/27 cams.

The duration of those cams, combined with the late intake timing, may simply be too much for the smaller displacement 3.8L. Both fuel consumption and performance are likely to take a hit.

The 08/09 cams are much closer to what was used in the 3.8L in the rest of the world (ROTW), but would benefit from being advanced by 6deg. (crankshaft). When advanced, the 08/09 set would match the 70/71 set.

Ignition timing, as always, benefits from being adjusted to local conditions and fuel choice.

So are you saying set the crank at 6 deg BTDC and the cams (theoretically) at zero? Would I need to do this with offset woodruff keys on the cams?

Thanks very much for your advice, Frank...

Yes, and yes.

Wait a second, see how little I know...

If crank is at 6 BTDC and cams are at zero and I have woodruff keys then I am 12 degrees...

If I am using woodruff keys then start with crank and cams all at zero and add the keys ..that would get them to six (except that all I can find are 5s- close enough?). A tooth on each cam is too much?

Keys are available in 4 offsets:

0.7mm [621 991 04 67] 4deg. crank
0.9mm [621 991 02 67] 6.5 deg.
1.1mm [621 991 01 67] 8deg.
1.3mm [621 991 00 67] 10deg.

Choose 6.5deg; chain and sprocket wear will negate the 1/2 deg. difference.

So , I am finding that these (02 67) are described as 3 degrees which equals 6.5 degrees at crank.

I already have one 02 67 and one 01 67 that I never used on my diesels. Hope SWMBO doesn't see this... talk about well-stocked larder...next to the survivalist rations...ready for the global thermonuclear war...

thanks again Frank...

My $.02. For normal driving you will want to stick with the stock US version 380 cams or cams that will give the equivalent duration and overlap when appropriately timed. I have owned both the EURO 380 with 9.3 to 1 compression and longer duration and greater overlap cams and US 380 with 8.2 to 1 (from memory) and shorter duration and overlap US cams. While the EURO engine will still breathe at 6000 rpm with 200+ hp it has very little low end torque and doesn't hit its stride until 3800 rpm or so. While it could do a respectable job cruising the Autobahnen it didn't do so well from stop light to stoplight. On the other hand, the US cammed 380 performs more like a US engine from that era. It has good low end torque, fuel economy and respectable performance from a stoplight until 4500-5K or so but made do with only 150 hp or so. If you go with either the EURO 380 cams or big block cams your 380 will probably be terribly overcammed and your wife will likely kill you due to the lack of low end grunt. Mark

The 70/71 cam set is the specified set for the 116.962NV/963NV engines.
NV = low compression.
08/09 cams are the retarded version of 70/71 cams, hence the recommendation to advance the 08/09 cams (above).