venting

RICKG · Member Joined: Aug 31, 2010 Posts: 1742 Location: SO IDAHO

http://www.cj3a.info/sibling/cjv35u/v1.jpg
on the link above item 4 is described as "metered".
i believe this means that the fittings are of the restricted type
with aprox .040 orifices, am i correct? btw there are many other great
drawings that i am referring to while building my vent system..
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

wesk · Posted: Sat Sep 15, 2012 10:11 pm Post subject:

I believe metered in that context refers to controlling the amount of vacuum available at the PCV valve which has a restriced pair of orifices and a check valve.

The 0.040 restricted fitting is the one at the wiper "T" that feeds the distributor vent system.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

BobW · Posted: Sun Sep 16, 2012 6:36 pm Post subject:

Everyone is correct.

Item 1 is metered crankcase vacuum, it is "metered" by the PCV valve.

Item 4 is metered distributor vacuum, it is "metered" by the orifice fitting in the wiper tee.

Rick, do you have a CJV35?
_________________
Bob W. Monticello, NY. 1952 CJ3A, 1952 M38, 1950 CJV-35/U

oilleaker1 · Posted: Mon Sep 17, 2012 12:16 am Post subject:

So, item 4 "T" sucks on the distributor which gets it's air supply in the crossover tube. I just put a 1/8 inch flare T there. If it doesn't have a .040 hole, what happens? John ( does the M38A1 have a metered fitting also like this?)

evanso1975 · Posted: Mon Sep 17, 2012 1:11 am Post subject:

You can fabricate that 0.040" fitting using a standard male connector:
http://www.cj3a.info/sibling/m38vent/vent3.htm

Owen.
_________________
Owen

1951 US Air Force M38
1944 F-1 1/2-ton Airdrome Trailer
1940 C15 Chevrolet CMP 11-cab
1939 DKW KS200 Motorcycle
MVT # 19406

oilleaker1 · Posted: Mon Sep 17, 2012 5:52 am Post subject:

Thanks Owen! I had a similar modification in mind, but getting the other T would be a simple change out. The ball check fitting was a mystery also and you answered that too! The question still remains: What happens if you don't install the T restriction? Wipers work like crap????? John

RICKG · Member Joined: Aug 31, 2010 Posts: 1742 Location: SO IDAHO

wesk · Posted: Mon Sep 17, 2012 9:31 am Post subject:

John,
The wiper "T" gets the resticted orifice in all M38's on the port of the "T" that goes to the distributor. The distributor venting system and the PCV valve are considered calibrated vacuum losses. This means the engineer took their use of vacuum into consideration when the carb metering schedule was developed. When you increase the amount of vacuum loss at either of these restrictions it causes an upset in carb metering resulting in overly lean mixtures.

Rick,

RICKG · Member Joined: Aug 31, 2010 Posts: 1742 Location: SO IDAHO

http://www.cj3a.info/sibling/m38vent/ventq.jpg

Wes, would you agree that im building my vent system to
the right drawing?
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

oilleaker1 · Posted: Mon Sep 17, 2012 12:37 pm Post subject:

This is a great thread! Thanks all. Now , did the M38A1 also have the orifice and at what location? I'm going back to it now and take a look. John

evanso1975 · Posted: Mon Sep 17, 2012 1:00 pm Post subject:

Check this vent parts list for the M38:
http://www.cj3a.info/sibling/m38vent/vent4.htm

If you look about 1/3 of the way down that list, the special fitting is part number 7348568. Now, page 87 of the G758 ORD 9 shows that same part number. So the M38A1 had the same fitting, apparently on the distributor vent line to the tee fitting. Seems logical so far.

This is my best guess for the location:
If you look at the diagram on page 70 of the ORD 9, then I would say that the special fitting is on the end of line EE that goes into the wiper tee fitting DD.

Hopefully, other members more clued up on the M38A1 vent system than me can confirm the location.

Owen.
_________________
Owen

1951 US Air Force M38
1944 F-1 1/2-ton Airdrome Trailer
1940 C15 Chevrolet CMP 11-cab
1939 DKW KS200 Motorcycle
MVT # 19406

wesk · Posted: Mon Sep 17, 2012 4:34 pm Post subject:

Yes the A1 also had that distributor plumbing and restricted fitting in the same wiper "T".
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

oilleaker1 · Posted: Mon Sep 17, 2012 5:57 pm Post subject:

OK, thanks much. John

wesk · Posted: Mon Sep 17, 2012 9:18 pm Post subject:

Rick,

Yes I would agree the late vent system is correct for your M38 if going with a factory resto.

_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php


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