Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: jedwards on January 14, 2014, 07:56:08
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Thank you for your forbearance of my seemingly endless questions.
In my efforts to achieve perfect idle, perfect starting and perfect running, I recently stripped down my distributor. I have an early 250 SL from 1967, so have the JFUR(6) type 051 with vacuum retard.
I stripped it all down and cleaned and checked everything, which was all good due to only 60,000 miles from new.
Once cleaned and lubricated, I re-assembled it, but on running the car, I found that I had somehow lost about 6 degrees of advance /retard.
When I set the timing to 38 BTDC at 3,000 rpm as per Dr Benz advice, I found that I had around 14 BTDC at idle, rather than my previous 8 degrees. This is not a huge issue in itself as the car rarely sits at idle in neutral or park, but the excess advance produces a rough idle in gear when under the influence of the constant speed solenoid.
The vacuum retard seems to be working OK and sucking by mouth on the vacuum tub does move the plate, so I am wondering if I have inadvertently assembled the distributor’s internals incorrectly.
The one area I was not entirely clear on was how the centrifuging weights and advance plate fit together. Referring to my image, how should the weights and the little counter rotational springs be placed, prior to the advanced plate being lowered into place? I assumed the springs would go on the outer side of the pins, and the weights help inboard while the plate was lowered. I found this very tricky so suspect this is where I may have gone wrong. I did work out that the advance plate has different length pins, so can only be installed one way, so wondered what the R and L signified.
I am missing something really obvious here?
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Hi,
The 2 springs in your picture are just retaining springs for the weights.
You are missing 2 further springs which attach to the bottom of the rectangular plate on the cam and then onto the two posts on the bottom plate. You have to ensure that the two pins on the rectangular plate engage in the slots in the 2 weights before attaching the springs to the posts.
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Hi Naj,
I have the two return springs in place, as you can see for the right hand image, so that are fine and correctly installed. I am less clear about the little retaining spins can either go on the inside or outside of the top plate's pins, but I don't know which, as they only become visible once the advance plate is lifted , and then they are are fee to move.
You might be able to help by telling me how the weights should sit when correctly assembled. In my left image, one weight is bring drawn inboard and the other is outwards. I believe this is wrong. Should they both be inboard as a result of the tension of the retaining springs, or both sitting outwards?
I cannot locate a image of the inside of that part of a 051 distributor to see.
Can anyone help with a picture?
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Hi Naj,
I have the two return springs in place, as you can see for the right hand image, so that are fine and correctly installed. I am less clear about the little retaining spins can either go on the inside or outside of the top plate's pins, but I don't know which, as they only become visible once the advance plate is lifted , and then they are are fee to move.
You might be able to help by telling me how the weights should sit when correctly assembled. In my left image, one weight is bring drawn inboard and the other is outwards. I believe this is wrong. Should they both be inboard as a result of the tension of the retaining springs, or both sitting outwards?
I cannot locate a image of the inside of that part of a 051 distributor to see.
Can anyone help with a picture?
Both weights should be inboard at assembly. The move outwards at speed to provide centrifugal advance for the timing.
Not sure about the retaining springs. Various types of clips have been used for retainers, even 'C' clips so I'm not sure they serve any other purpose.
Naj
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These may help.
I have the same dissy and took these a few years ago when I stripped mine down. Yours doesn't look quite the same.
There is a specific dissy grease that you get from Bosch for this job. It's very thick. I recommend you use it.
Dan is the dissy ninja, I recall.
JH
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D&A of the distributor isn't too difficult. Setting them up so that they maintain dwell angle and produce a proper advance curve can only be done with a distributor tester.
The rebuild kit is now twice as much as it was last year at 160 dollars. Expect everything MB to increase in price this year by at least 50%.
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Thanks for everyone's help and input.
I stripped it, ultra-sonic cleaned everything, reassembled as per the guidance and now have 8 BTDC at 750rpm and 38 BTDC at 3,000 rpm.
Many thanks once agin.
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