Posted: Mon Apr 27, 2015 10:31 am Post subject: Distributor housing vacuum port plugged
As shown in the picture below, my vehicle as purchased has the vacuum port for the distributor housing plugged with a red pipe plug. The hard line to the carb air intake is in place.
I saw in another thread that the line runs from the fuel/vacuum pump, to a Tee with one side going to the wipers and the other side of the Tee going to this port. My question is not how to route the hard lines or what connects to what, but rather as I understand it there is a .040 restriction orifice in the line coming off the Tee fitting and going to the distributor housing. What was the goal in using that restriction? And what is the correct diameter for the hard line running from the Tee fitting to this port?
_________________ Wade
Baton Rouge, LA
M38A1
M35A3
M37B1
The purpose of the reduced orifice is to create a calibrated small vacuum leak that can be managed by adjusting the richness of the carb. This means the final carb adjustment will not be too rich to cause running issues but will be rich enough to make up for the additional vacuum leak created by the line to the distributor. There are many posts on this topic. You can search these questions using the search function at the top of the page or go to Google and type in www.willysmjeeps.com, distributor vent tubing or wiper T.
ORD 9 page 89 3rd item notice tubing listed as part of the assembly is 44-T-5080-10 , 26" length. Then continue down through that section looking for the noun TUBING. Page 91 44-T-5080-10 2/3 rd's of the way down the page.
Posted: Tue Apr 28, 2015 9:44 am Post subject: Distributor housing vent plugged
Yes, I have looked at Bob Westerman's summary and it was helpful.
In regard to the A1 however, I'm not catching something here in connection with the orifice restriction at the wiper Tee. Since the "intake" side of the distributor vent is upstream of the throttle plate, how would that affect the carb anyway? I do note that ultimately the vacuum flow is from the engine air intake, through the distributor housing, through the wiper Tee, into the "intake" side of the vac pump and back to the air intake, all upstream of the throttle plate.
I'm at work and don't have all of the manuals spread out in front of me so if I've missed the end routing of the vac flow and it does enter the intake manifold on an A1 after leaving the vac pump, please just note that error. Even if that is the case though, wouldn't the operation of the wipers sometimes and not at other times produce a variable signal to the carb?
thanks,
Wade _________________ Wade
Baton Rouge, LA
M38A1
M35A3
M37B1
All the suction devises on your jeep originate their SUCTION at the intake manifold port just below the carb. The fuel/vac pump just boosts the suction a bit. Actually the wipers are also a calibrated leak since they are vented to the atmosphere until they are operated. Then they are closed to the atmosphere on the suction side by the flapper inside the wiper. The wipers use the larger tube hole without the orifice since they have a greater suction need to function. Yes they still have a small effect on manifold vacuum relative to fuel flow when they are in use. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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