1982 380SL camshaft replacement options

[Rev. Buzz]

Gentlemen
I'm helping a friend who has recently aquired a 1982 380SL. He has done a very good job cleaning & repairing
This neglected jewel ; complete fuel system cleaning & overhall, interior, paint & body. The engine has camshafts with rust to the point of pitting on 3 lobes on each cam. This is enough to justify replacement.
My question is... What is the best / hot setup for this motor ? Timing chain is tight & doublerow.
Any help is greatly apreciated.
Thank You in advance !
Sincerely
Rev. Buzz

[cwmoser]

I pulled the cams from a 1981 European 380SL.
The Euro version has more horsepower than the USA version of the 3.8L engine.
When you mention the best "hot setup", I wonder if replacing those Cams
with Euro versions would make the engine more powerful. I don't know all that
makes a Euro 3.8L more powerful.

[Diseasel300]

The Euro cars have no emissions controls, so they don't have all the horsepower strangled out of them.

[Frank Reiner]

RB:

The engines in the US spec 380SLs are very much limited by the low compression ratio of 8.3:1. While a change of valve timing will bring some improvement, the word "hot" would not occur to most folks.

That said, cams of code #s 70/71 or 04/05 (left/right) will be better than the 62/63 or 68/69 that are the usual US spec cams.

And, if you are considering the use of heads from an iron block engine (3.5L), they do not directly bolt on.

[Rev. Buzz]

Thank You Gentlemen Especially Frank
What would it take to put 3.5 L heads on a 3.8 L ?
I have heard that this would raise compression to around 9.5 - 9.75. That would be wonderful if possible !
Also how difficult is it to change out the cams ?
Hopefully this doesn't envolve removing the heads.
Thank You Gentlemen !
Sincerely
Rev. Buzz

[Frank Reiner]

Originally Posted by Rev. Buzz

Thank You Gentlemen Especially Frank
What would it take to put 3.5 L heads on a 3.8 L ?
I have heard that this would raise compression to around 9.5 - 9.75. That would be wonderful if possible !
Also how difficult is it to change out the cams ?
Hopefully this doesn't envolve removing the heads.
Thank You Gentlemen !
Sincerely
Rev. Buzz

To address the matter of CR only, the heads from the 3.5 engine would give a ratio of 9:1 - 9.1:1. The change in total chamber volume is on the order of 6 cc; ~60 cc to 54 cc.

Compression ratio aside, five head bolts in each head are in a slightly different location in the block, and, they are ~2 degrees inclined from the normal. There is also the matter of differences in chain tensioners and tensioner rails, steering pump mountings, alternator mountings, and air injection provisions.

If cams were to be exchanged, ones from other aluminum block engines do exchange directly, without head removal, provided that the head bolts that pass thru the cam stands come out cleanly.

A complete 4.2L M116 engine may well be the most satisfactory approach. All ancillaries, including exhaust manifolds, attach directly. Only the intake system (air guide & air/fuel meter, WUR), oil pan, and oil filter from the 3.8 would be reused.

[rowdie]

Heads from a 3.5 will not work on a 3.8.

[Rev. Buzz]

Thanks You Gentlemen

[Rev. Buzz]

Ok, Now I'm looking for a 4.2L motor. What is the better/ more HP
4.2L motor to look for ? Again Thank You Gentlemen
Sincerely
Rev. Buzz