intake cover sensor holes

[jethro]

Im trying to make a new intake cover. (3/4 6061 plate) (the old one is very corroded on top-)
looks pretty easy- except for the 2 holes that the 2 sensors screw into.
Looks like a temp and a pressure(?)
They have the same size and pitch on the threaded holes- but Im not for sure what size they are and if they are tapered or straight threads. They sort of look tapered....

Does anyone know what diameter and pitch they are ?????

Tim

[classiccarjack]

I haven't done this modification on a Cummins, BUT, I have done a similar modification on some of my fuel injection swaps on customer cars. My experience with most sensors, is that they have a NPT thread. The two most common have a 27 or a 28 pitch. One thing you could do, is remove a sensor and screw it into a die to help you figure out what Tap you will need to get the job done. Most taps have the required predrilled size hole stamped on them. If not, use a drill chart to help you choose the right size. Harbor Freight does offer lettered and numbered drill bits, if you need the non fractional size at a reasonable cost. The cheap bits will work great with aluminum. Don't forget to use tap oil.

I hope this can help you begin your project. Please let me know how it turns out.

[PToombs]

1 sensor should be for the KSB, and the other for the grid heaters, I think. I can't remember if mine is screwed in or is just a thermistor touching the plate.

[jethro]

I tried some fitting into the old hole-- appears to be 1/2 npt pipe.
Wouldn't ya know - I have every size pipe tap from 1/8 to 1 inch EXEPT that one----

One sensor looks like a bulb temperature device not sure about the other one.

Tim

[classiccarjack]

I tried some fitting into the old hole-- appears to be 1/2 npt pipe.
Wouldn't ya know - I have every size pipe tap from 1/8 to 1 inch EXEPT that one----

One sensor looks like a bulb temperature device not sure about the other one.

Tim

Let us know how it turns out. I want to research this area to see if some affordable performance can be had.

[jethro]

The manufactured plate worked ok-
Both sensor holes were 1/2 npt. The only snag on installation was that I may have made it harder by using 3/4 inch thick
aluminum. The extra height made the fuel line brackets no longer fit. I had to make all new ones- and they still barely cleared.
If I was going to do it again- I would use 1/2 aluminum. (2024 t4 if I could find it-)
I also removed the heater box and mounted the air horn directly on the plate.
I don't expect the new plate to improve performance- but getting rid of the heater might help a little......

Tim

[classiccarjack]

Thanks for the update.