Attaching only one distributor vent line?

[ZGjethro]

I have brought this up before, but this is a different idea, so please bear with me. A year ago I welded up a straight pipe intake with a K&N filter on it. I need to attach lines to cool my coil but I am not worried about venting everything into to intake for fording purposes or originality. I noticed the two coil vent lines are pretty close to each other on the original intake horn. Would I have greater vacuum if I only tapped my new intake for one line? How much pressure differential is there between the two tapped holes in the original intake? I would put a small filter on the other line. Previously I had floated the idea of using the gas pump vacuum assist to cool my coil. Now I want to remove the fuel pump and blank it off. My wipers are going to be electric soon.

This truck was missing the brake and gas vent lines (bent off on the engine head). The only other vent I might be tempted to tap into the intake is the oil filler vent.

[MSeriesRebuild]

You need both distributor lines hooked up to get the forced air flow. Like I said before, the fittings must be the correct type also to make it happen.

The vent opening on the oil fill tube is a must too; although it will work open ended if you choose, but I would not recommend that because of possible dirt entry. If you simply plug it off, pressure within the crankcase will build forcing oil past the rear main oil seal creating a hefty leak.

[hbb]

My question is what would you be gaining by redesigning a system that works very well? all of the pieces that are needed can be found locally or on the net with out a huge investment,but if you really want to end the worry about the coil cooling issue dump the shielded distributer and put in a civilian unit with a open coil and problem solved, oh yes civi oil pump to drive the distributer.

hb

[M37UK]

My question is what would you be gaining by redesigning a system that works very well? all of the pieces that are needed can be found locally or on the net with out a huge investment,but if you really want to end the worry about the coil cooling issue dump the shielded distributer and put in a civilian unit with a open coil and problem solved, oh yes civi oil pump to drive the distributer.

hb

Or you could use the existing military distributor and mount a civvy coil somewhere else and feed the required power cables to it.

[ZGjethro]

I am very happy with my rebuilt distributor with the electronic conversion, so I am not going to change that.

Charles, Is air forced down both tubes, or is one a return path. If air is forced down both then I will tap my intake for two holes. For some reason I was thinking they operated on a loop system with a pressure difference in the intake creating air flow. I am just trying to understand this truck better. I have all the fittings and lines from the original factory intake system, so there would be no cost to me, other than the cost of a tap or two. I will probably put a small K&N type filter on the oil vent line as I see no reason to vent it into the intake.

HB, I can duplicate the factory system, but it was designed that way mostly to make a closed loop for water fording I think (see above paragraph). If I do no have to drill and tap as many holes in my intake, I won't. I get the feeling I will be making it original.

[MSeriesRebuild]

I am very happy with my rebuilt distributor with the electronic conversion, so I am not going to change that.

Charles, Is air forced down both tubes, or is one a return path. If air is forced down both then I will tap my intake for two holes. For some reason I was thinking they operated on a loop system with a pressure difference in the intake creating air flow. I am just trying to understand this truck better. I have all the fittings and lines from the original factory intake system, so there would be no cost to me, other than the cost of a tap or two. I will probably put a small K&N type filter on the oil vent line as I see no reason to vent it into the intake.

HB, I can duplicate the factory system, but it was designed that way mostly to make a closed loop for water fording I think (see above paragraph). If I do no have to drill and tap as many holes in my intake, I won't. I get the feeling I will be making it original.

It operates as original in a push-pull cycle. The opening of one fitting is turned into the intake air flow while the other is turned in the opposite direction; this creates a drawing effect on the return side. The push without the pull would not be nearly as effective in creating a forced flow if it did at all.

[ZGjethro]

Thank you Charles. The fittings on my original intake do not do that. They are both perpendicular to the air flow, which did not seem very efficient to me. That was why I was looking to redesign the system. Now I need to find the original style fittings. Any pointers as to where to go? Do you carry them?

[MSeriesRebuild]

Thank you Charles. The fittings on my original intake do not do that. They are both perpendicular to the air flow, which did not seem very efficient to me. That was why I was looking to redesign the system. Now I need to find the original style fittings. Any pointers as to where to go? Do you carry them?

Fittings are very simple to make yourself if you have a tubing bender and soldering skills. 1/4" brake line tubing is a perfect fit for soldering into a common weatherhead brass fitting. Call me if you need further assistance.

[ZGjethro]

Charles, I am assuming the radius of the bend should be just large enough to allow the fitting to slide into the intake and rotate without hitting the insides of the intake. Thanks for steering me in the right direction here. I can handle any soldering. Thanks.

Hb, I was wrong about the distributor cooling system. It looks like I will be hooking it up just like it was designed

[MSeriesRebuild]

Charles, I am assuming the radius of the bend should be just large enough to allow the fitting to slide into the intake and rotate without hitting the insides of the intake. Thanks for steering me in the right direction here. I can handle any soldering. Thanks.

Hb, I was wrong about the distributor cooling system. It looks like I will be hooking it up just like it was designed

A 90* bend with any typical brake tubing bender should work; cut the tube to the correct length after bending is complete.

[hbb]

Jethro

I think you will very happy when you get the lines cut and installed and operating, will look right and work great!!
I don't recall if you mentioned that you have the TM's for the M37 and if you don't they will help more than you could ever imagine and the cost of having the whole set will save you in the long run.

Good luck
hb

[ZGjethro]

hb, I do have the TM's for the carb, clutch and 9-8030. After you mentioned them, I found a great picture (figure 103) on page 199 of the distributor cooling lines and fittings

[hbb]

Great now you have a better idea of what Charles was talking about and a better idea of how to make those up! you should be-able to get that done with out much blood shed maybe a few foul words, but that should get you on the road!

hb

[ZGjethro]

I have been driving it for the last 20 months with no cooling to the coil. I thought I'd think about starting that project.

[ZGjethro]

Today's truck project was hooking up the distributor lines as they were designed. I bought a 1/8x27 pipe thread tap, tubing bender, and tubing. I altered the intake fittings so a ninety degree 1/4" line faced each way in the intake pipe right in front of the choke plate. I bent up some beautiful parallel 3/16" lines from the intake to the distrubutor. I was curious as to how much air flow came out of the positive pressure line so I started up the truck and put my finger over the fitting of the forward (air filter facing) fitting. I could not feel any flow or pressure at any engine rev. Is this venting system designed to be pretty passive and just barely move air, or should there be significant air flow?