Quote:
Originally Posted by 1983/300CD
The T's in my 1982 booster line were open (large holes).
The T's in my 1983 booster line were restricted.
When I ordered replacements, both lines sent had T's with the larger holes.
The only reason for having orifices of smaller size in the T's would be to increase vacuum to the brake booster, but as long as your system is tight enough to maintain ~25" to the booster, all is well.
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1983/300CD,
One way or the other, the restrictions are needed... unless your vacuum pump is wearing out!
I have gauged the I.D. of some of several of these "T"(s) on the main vacuum line and found most to be ~0.8mm. IMHO I would equate "open" to be ~ 2mm or larger which is the opening in the largest of the MBZ in-line orifices... thus also IMHO, IF new replacement main vacuum lines come with "T"(s) that 2mm or larger openings, I believe it would be necessary to use in-line orifices that are 0.9mm or smaller to reduced the
"strength" of the vacuum such that you would be able to properly adjust the vacuum on cars with a vacuum control valves [VCV] mounted on top of the Injection Pump (IP). Otherwise you would NOT be able to properly adjust the VCV so that the tranny's modulator valve would see the proper varying vacuum signal simulating changing throttle.
I agree that restricted orifices [whether in the main line "T"(s) or in-line orifices]... these are there to help "conserve" vacuum for the brake system, but IMHO these restrictions are also there to provide a final degree of "tweak" or control of the vacuum being supplied to the various vacuum using components... for example EGR, VDC, modulating valve etc.
So IMHO you either have to restrict the vacuum at the main line or bother there and later with in-line restriction(s). One of the diagrams on the
www.PeterSchmid.Com WebSite actually gives you the sizes of the 6 or so color coded in-line orifices!
Check out:
http://www.peterschmid.com/vacuum/1977_1985/617_95/1981_1984.jpg
Regards,