Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: Dave H on January 12, 2015, 19:40:59
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I am rebuilding my 250 m129 motor.
I have a perfect condition 09 cam c/w towers which I acquired from Germany.
Can I use it...? Will it cause any valve piston / piston clash ?
The 86 cam i have has a 130 duration but the 142 of an 09 sounds better .
Has anybody done this ?
Will I run into any unforeseen problems ?
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I'm using a 230SL cam in my 129 engine and it works quite well. I changed the cam timing slightly by using an offset woodruff key to advance the intake valve to about 12 degrees BTDC which is similar to a euro 280SL cam. You can use any combination cam and towers in a 129 engine as long as it's not a late 280SL cam.
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The cam towers are different diameters with the later camshafts. You will need to check these. I am not sure when they changed.
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I have been playing with camshafts quite a bit, on M116/M117 engines though. In my experience, displacement does influence quite a bit the way a camshaft profile will work on an engine. For a given profile, the smaller the displacement, the more aggressive the engine behavior. Fitting a 09 camshaft on a 250 will have your engine be more aggressive than a 280 fitted with the same camshaft. Your torque and power curves may be pushed up in the rpm range by quite a bit, and you will loose some torque at lower rpm, with some consequences on driveability in town for example. One way to deal with it is to advance the timing of your camshaft by a few degrees to get your curves back a bit lower in the rpm range. Another way, especially if you like the aggressive nature of the engine, is to adapt the rear end ratio so as to get back into sufficient torque when you upshift. Nothing wrong with any of it, but you will be entering uncharted territory as you will have to adapt the timing of your camshaft to your liking, and then the injection and ignition adjustments to it. The difficulty is that standard/stock adjustments won't really apply anymore. But if you like tinkering, it's a lot of fun!
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Thank you Dan , Joe and GGR.
This is just the information i was after.
I will have to dig a bit deeper when i get round to doing it but it will give me something to tinker with after the restoration is complete.
(probably in the next ten years at this rate )
Thanks guys
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Dan
Just to confirm.
You advanced your timing to 12 or 12.5 ?
Cant find the post but seem to remember a 12.5 setting from somewhere.
Is 12.5 too much ?
I will advance and accurately set the v/v timing with a DTI and an off set woodruff key.
Gonna call her the Biege rocket !!!
230 exhaust header set up also sounds the way to go.
:D
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Dan
Just to confirm.
You advanced your timing to 12 or 12.5 ?
Cant find the post but seem to remember a 12.5 setting from somewhere.
Is 12.5 too much ?
I will advance and accurately set the v/v timing with a DTI and an off set woodruff key.
Gonna call her the Biege rocket !!!
230 exhaust header set up also sounds the way to go.
:D
Biege Rocket? It doesn't grab me like '' Red Rocket. ''
I think I used 12 degrees or whatever the euro 280 cam is set at. I figured it wasn't a good idea to go any further than that and that a consideration for a proper safety margine had been accounted for by the factory.
I would agree that all of the normal timing specs and other info normally used to set up one of these engines goes out the indow the more you change things. My car is highly modified from stock yet it retains a stock apearance with period correct 113 parts. As an example, I'm running 40 degrees ignition advance and yet it never pings. You would see a big difference using header pipes.
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Got these standard 250sl specs off the site.
breaker point gap: 0.3-0.4 mm
dwell angle: 38 degrees +3, -1 degrees
Bosch distributor part #: IFUR 6 0 231 116 051 (MB part no. 001 158 02 01)
timing: 8 degrees BTDC at idle, and 30 degrees BTDC at 3,000 RPM, both without vacuum advance connected
CO value at idle: 3.5-4.5
The 40 degree advance your running, is that 40 degrees BTDC at 3,000 RPM, without vacuum advance connected ?
I will be using a 123distributor so hopefully one of pre set curves will suit it.
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Those numbers are correct depending on how you do things. I set my timing to about 40 degrees at 3,000 RPM. I leave everything connected because that's the way it will work when you're driving your car. If you unhook the vacuum line you should see an automatic 10 degrees of advance if your distributor is working properly. Sine you are using the 123 unit, just make sure you are getting full advance before 3,000 RPM. In most cases it's probably fully advanced by 2,700 RPM but 3K is more of a max amount rather than the actual setting.
We are now using NGK BP5ES spark plugs and these are the only plug I recomend. The standard gap is .032'' but you should be able to open them up to .035'' with the 123 distributor. Watch out for carbon core coil wires or spark plug terminals of more than 1K ohms. Ideally, you shouldbe looking for 6 - 7K of total resistance in your entire ignition wire ( secondary ) system; 5K for the rotor and 1K at the plug terminals. You don't need any resistors on the coil wire or distributor cap terminals.
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Thank you Dan.
I will keep you posted.
Block is in for Rebore at the moment so it will be some months.
Got a getrag 5 speed and Mark Turnbulls kit to mate up to it.
Coincidently he lives 15 miles up the road from me, he has sold his kit all over the world but never expected to sell one on his doorstep.
His car is beautifull in china blue and drives like a new car.
The 5 speed makes all the difference .
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All of the 113's should have been 5 speeds.
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Dan, I agree .... as long as they are automatic, but could even be a 6-speed automatic! :)
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If you live in a big city the auto probably makes more sense. I don't think anyone was making 5 speed autos at that time, were they?