Do you have to tap the air horn to install a boost gauge?

[V6power87]

Or can you just use the pipe plug that Cummins puts kinda behind the fuel filter.



I realize that it is a big plug so it might have to bush the heck out of it.

 

[RustyJC]

Check out http://www.piersdiesel.com - Piers has a bolt that replaces one of the manifold cover bolts that will give you access to manifold pressure.



Rusty

 

[JR2]

Yes you can use the port toward the firewall from the fuel filter. I have been using this port since I installed my gauges and it works fine as far as I can tell.

 

[LSMITH]

I use the plug in the manifold as well with no problems. I used a 3/4 NPT to 1/2 NPT reducing bushing and then 1/2 NPT to 1/4" reducing bushing. If you have an electronic pressure sender without a seperate ground do not heavily tape the threads or use pipe dope, the readings will be skewed and erratic. You can tape the threads if you only tape two or three theads, hope this hepls.

 

[V6power87]

Thank's guy's for the quick replies!



So why does everybody talk about drilling and tapping the air horn when they could just get manifold pressure there?

 

[LSMITH]

Dan, some guys feel that the air horn is more accurate, and some others have mechanical guages that rattle from the air in the intake pulsing with the valves opening and closing. It is kind of a brown rice/white rice thing. I think the mechanical guage rattle is the main reason for tapping the air horn, it absolutely drove me nuts so I got an electronic guage rather than fool with snubbers or tapping the air horn. Hope this helps.

 

[me4osu]

MAP TAP

Like LSmith stated, I tapped the air horn because I bought a mechanical gauge. I had read some posts where some manifold sense gauges were rattling because of the pulsation from being so close to the valves. Wasn't that hard to do.

 

[Bigsaint]

I'm still using the 3/4 " plug as my source, has worked well for me so far. If you are going to use this source, take the truck for a short ride and let everything come up to temp. , it will make the removal of the plug a piece of cake.



Scott W.