Tuning Tips? Do Tell!!

[n/a]

I have set up the throttle linkage correctly on my '70 280sl, cleaned the throttle body and adjusted the throttle plate, and was wondering about additional tuning tips that other members found useful in getting their engines to run smoothly while producing maximum power.  Do tell, thanks!

[A Dalton]

Aside from the normal spec asjustments , the most important tuning tip one should be aware of is sequence......
 I set ignition specs first, valve specs second, and lastly, Fuel adjustments
Fuel should ALLWAYS be last..otherwise , you are wasting your time.

 Also note that final tweaking is done after several road test, as every engine and driving styles are different.. once set , try and stay with the same petro......[ I think I like that "petro" over gas
technique.... b/g]

[J. Huber]

Maybe already understood:

new Bosch plugs (W7DC or WD9DC) at.031-.032
Bosch Red Coil & 1.8 ohm resistor
Bosch or Beru non-carbon wires

Highest octane fuel you can get.
All filters clean and clear.
Talk nicely to it. German or english.


James
63 230SL

[Cees Klumper]

Very important I found is that the throttle/FI pump linkages are nice and tight.
Make sure all the air hoses, also the one to the brake booster, are tight and there are no leaks.
Also there should not be leaks at the manifolds or manifold-to-exhaust-downpipes.
Make sure the breather tube over the valve cover is clear.
Make sure the cold start injection valve (CSV) on the intake manifold is not leaking and that the cold start thermostat on the FI pump is operating properly (closes as engine warms up).
Fuel/air mixture at idle at correct CO level.
Check the resistance of the ignition wires and caps (1K ohm).
I guess it is worthwile to have your fuel injectors tested every couple of years for proper resistance/pressure and spray pattern.

A Dalton - could you not also start with the valve specs rather than with the ignition? Valve adjustment has to be done with the engine cold, so if you set the ignition timing first (which should be done with the engine at operating temp AFAIK), you will have to wait a few hours for the engine to cool down, while the valve adjustments are not influenced by the ignition timing?

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[A Dalton]

C
 Yes,you certainly could..and if you are doing it right off, thats even better..
 I  do it the other way around, as I like to get the dist out of the way before tearing in to the cover , plugs , cross linkage ,wires, etc ..pleanty of time ..

 The main point being, these get done before fuel ... specially timing.

[mdsalemi]

I'd agree with A Dalton about the sequence of events.  I am reminded of an old service manual I had for working on the original Austin Cooper S.  It said something to the effect of "Carburetor is a French word meaning 'It's the electrical system, stupid'. Now I know we don't have carbs but you get the idea...

I'd also consider the NGK plugs.  The general consensus is that the Bosch plugs subject to a bit more fouling, a bit easier then the NGK's.  The NGK's in the BP6ES and related heat ranges are designed for Japanese racing motorcycles--in fact sometimes you might have to go to a motorcycle shope to find them in stock.  These motorcycles are extremely high revving, and 2-stroke--so they are better designed (so I'm told...) to handle the peculiar conditions inside our M130's and related engines.

N.B. Plug fouling with brand new 113's was noted in less then 1,000 miles in original test reports dating to the 1960's.  So if you foul your plugs--its normal!!

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[ja17]

Hello James,
I like to change the fuel filter first if it  has not been changed already. I then start off with a fuel pressure and volume check. You can buy or make a tester very easily for this. If the fuel pressure  and volume is insufficient all the tuning in the world is useless. The air cleaner on the injection pump should be checked to makes sure it is clear and the cold start valve on the intake should be checked to make sure it is not leaking. The main air filter should be checked, cleaned  or replaced. The valves should be set to specs cold and the compression should be checked with warm engine. ( I re-torque the head before valve adjustment at 12,000 mile intervals). The spark plug cables and coil wire and their leads should be tested with an ohmeter to makes sure they are fine.
These items are important to see through before the actual "tuning". The term "tune-up" is often associated with changing cosumable items such as ignition point, spark plugs, wires , mixture adjustments. etc.  However Mercedes describes most of the steps in a tune up in their service booklets and owner's manuals. A "E service" covers most of these items and many more other maintenance procedures. You may have about fifty procedures to deal with on an "E" service. The "D"
service at 9,000 mile intervals is a minor tune-up.

I always  said that the "E" in E service stoo dfor the condition of your wallet when finished (empty) .

Joe Alexander
Blacklick, Ohio

[Malc]

To help give your car the "full monty" at least once a year no matter how little or much you use it: to keep in tip top condition I would suggest every 6000miles (10000kms) or six months

oil and filter
fuel filter
Air filter
valve clearances
points clearance
check very carefully rotor arm and distrbutor cap change if any doubt about condition.
Gearbox and rear diff oil level/change
only after above twiddle with timing/tune up.....

brakes inspect

In addition

Change plug leads and lead to distributor if over two years old
Sparkplugs

Check condition of antifreeze: change every 2 years anyway, back flush system when doing so

Gearbox and rear diff oil level/change
brakes inspect

change brake fluid every 2 years unless using silicon based

Just a thought
Malc

[graphic66]

Don't forget to check your radiator for electrolosys. This is stray electric current passing through the car that can eat a head and radiator up in no time. To check simply hook a voltage meter to the negative post of your battery and submerge the positive lead of the tester into your antifreeze, first with the car off, then running. You should have no more than .05 volts. If it is higher you have a problem, the most common is a bad ground to the engine. If that isn't it then start pulling fuses until the voltage drops and you can isolate the leaking cirquit.

[Malc]

Wow Graphic!
Thats a new one on me. I know a radiator, alloy head, iron block and water can make a nice "battery" and cause all sorts of corrosion problems, hence I am pretty strict about renewing antifreeze every couple of years, but I never thought about testing it that way.

I have heard that VW make a new antifreeze , I think it's called G12 which never has to be changed, is this true, anybody know?
Malc