Pagoda SL Group

W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: Worldflier on June 15, 2021, 18:18:07

Title: Odd adjusting screw on throttle body. Ideas?
Post by: Worldflier on June 15, 2021, 18:18:07: Good day,
While chasing my warm starting issue, I removed the throttle body (throttle plate assembly?) from the intake manifold and noticed a tiny set screw near the back of the assembly.

Does anyone know for what this is used? It connects to a vacuum port in the body, but spraying cleaner into the hole didn’t reveal where it leads.

Btw, this car is a 1967 230sl with the M127 engine.

Thanks for your ideas!
Dre
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: Worldflier on June 15, 2021, 18:19:23: One more picture.
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: Pawel66 on June 15, 2021, 21:16:52: Is it not a vacuum port? For certain tests.
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: Peter on June 15, 2021, 21:37:40: Just what I thought.
See Hayne manual.

Peter
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: Tyler S on June 16, 2021, 03:49:55: That grub screw is very small, non magnetic, and blends into speckled epoxy flooring. Never did find it.
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: wwheeler on June 16, 2021, 03:56:45: I have seen that test before and never knew what grub screw they were talking about. Interesting. Anybody ever done that vacuum test? Seems like the split linkage test would have about the same effectiveness and a whole lot easier.
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: Tyler S on June 16, 2021, 13:13:40: Wallace,
I have done that test before and all it really gets you is a visual representation of the vacuum level at closed throttle. It isn’t much different than the split linkage test.
BTW there is one part of that procedure I do during a split linkage test. I disconnect and apply my own vacuum to the distributor with a hand pump as it can skew your results. On an 051 distributer, The timing advances when you crack the throttle via the vacuum retard setup. Even if the engine is lean it can raise the RPM significantly as advancing timing will allow for a leaner mixture.
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: wwheeler on June 16, 2021, 19:50:44: Good point and I will try that! Thanks for the tip. Maybe add to the Split linkage tour?
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: Tyler S on June 17, 2021, 00:39:43: I edited above to include that I use a hand pump to supply my own vacuum to the distributor. Not sure how I forgot that part.
Title: Re: Odd adjusting screw on throttle body. Ideas?
Post by: col320ce on June 17, 2021, 03:06:58: I made a plastic connector to measure the vacuum where the screw is... Worked well. Then broke it and tried to make another out of brass but failed.