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Manifold pressure line?

B

buz

Well Known Member
What do most people use for a manifold pressure line from engine to sensor(vision)?
Also I am presuming to use the primer port on one of the rear cylinders to access the MP on the engine. The other 3 used for primer.

BUZ
 
Van's little kit....

The firewall forward kit from Van's that I bought had their manifold pressure sensor line installation subkit. Had the right fittings and hose to get back to the firewall. And yes, I tapped off of #3 primer port.

Paul
 
Hose and fittings...

The kit is basically the fittings for the engine (and I THINK the firewall, and a fabric-jacketed hose. Not brass tubing.

Paul
 
Each cylinder has an upper and lower tapped hole on the intake side, so you can have MP pick-off and primer on the same cylinder.

John Siebold
 
Here is a pic of the hose and fittings installed on my 7A. You get the fitting to the cylinder, the hose, a bulkhead fitting that you may or may not use, depending on what gage you use and how you plumb it. I use a different AN4 bulkhead fitting.

Roberta

wiring43wg.jpg
 
Hey Gil, I use Pegasus, too. They are in New Berlin, WI and on my way home from work. The hoses I didn't get from Van's came from Pegasus. Good people and business. They have a great selection of hoses and AN fittings.

Roberta
 
Copper is OOOOLLLD school

Copper works but what they said above. The thing is if the line breaks or leaks it makes the engine run real rough. BE SURE TO USE A RESTRICTOR fitting. Using wide open AN fittings is bad and you can get some blow by (fuel/oil mix) in the hose that can migrate to the gage or transducer (sender). You can buy restrictor fittings or make your own. The orifice dia is usually like 1/32. G
 
robertahegy said:
wiring43wg.jpg
Click to expand...

Opinions vary on this, so take it as you see fit... but using zip-ties directly on the engine mount tubing is a no-no IMO. Zip-ties have been known to collect dirt underneath and act like a saw, chafing the paint off the tube (sets you up for corrosion) and, if left unchecked, abrading the tubing enough to cause a failure.
Putting the zip-tie over a couple wraps of self-vulcanizing silicone tape would be better. An Adel clamp would be much better. An Adel clamp over a couple wraps of self-vulcanizing silicone tape would be best.
 
You are absolutely right, Jarhead. This photo was taken during construction and the hose was just temporarily held in place that way. A double adel clamp is now holding this hose as well as other areas. Good call. That tiewrap would also chaffe the hose over time.

Roberta
 
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robertahegy said:
This photo was taken during construction and the hose was just temporarily held in place that way.
...

Roberta
Click to expand...

Gotcha. I suppose I shoulda thought that through some more before posting... after all, there's no ignition harness or exhaust system in sight in that pic, either. :eek:
 
Your post was well put. Someone may have thought that to be OK. Always good to point out good work practices, and bad ones.

Roberta :)
 
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I have my manifold pressure line that goes to my Dynon sensor installed just like Roberta has. I forgot that my P-Mags need to be connected to a port as well. Am I correct in assuming I can use a different port for the Mag's?

Larry
 
Which Hose Should I Use

Is Aeroquip 306 rated well enough for a manifold pressure hose? I liked it because I can put a fitting on one end and leave the other open for a hose clamp on my Manifold Sensor which I mounted on the fire wall. The hose is rated -65 to 160 F. I would think that is good enough. What kind of temperatures am I dealing with under the cowl. I also have the Vans Kit but didn't want to use it because I didn't go through the firewall and the hose has a fitting on each end. The nearest I can tell is that it is Aeroquip 303 rated -65 to 250 F. If I take the hose fitting off one end of this hose will it unravel or do anything such that I cann't put it on my manifold pressure sensor with a hose clamp and connect the end that still has the fitting to the engine?
 
That's true but there is another cheaper way

jarhead said:
Opinions vary on this, so take it as you see fit... but using zip-ties directly on the engine mount tubing is a no-no IMO. Zip-ties have been known to collect dirt underneath and act like a saw, chafing the paint off the tube (sets you up for corrosion) and, if left unchecked, abrading the tubing enough to cause a failure.
Putting the zip-tie over a couple wraps of self-vulcanizing silicone tape would be better. An Adel clamp would be much better. An Adel clamp over a couple wraps of self-vulcanizing silicone tape would be best.
Click to expand...
You are right of course, but as you can see you can EAT off of her engine compartment. After a long long time you are right the powder coat will abrade and the hose mesh wear, but no time soon and from the looks its easy to inspect. With that said there are two easy ways to fix the wear issue you mention. The first is wrap the hose and engine mount each with silicon tape and than zip-tie together. The other way is using a zip and a short piece of hose:

I learned this trick long ago, I think from the eaa mag and most builders know it, make a stand-off by threading the zip-tie through a short piece of vinyl or rubber hose (twice), making a figure-8, one loop around the engine mount, the other around the hose like this: O=O.

The trick above makes a nice stand-off and it's a lot lighter and cheaper than full Adel clamps with nuts and bolts. Nothing wrong with the latter but for a little old no-pressure manifold line its pretty slick (but not military approved). Instead of a short piece of hose some just use a second zip-tie around the main zip. BTW notice you lay on your stomach and pass gas, cool. :D (ie, KC-10 boom operator)

Cheers George
 
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