K3LA mod and upgrade

Main Train Horns
1

So… really I done it, I drilled my horns…

I’ll start from the beginning. As stated in my recent thread, I was having a leak problem with my Parker GP400 valve. Well, I decided to go with the GC Xtreme 350 3/4" valve. The valve looks superior compared to my Parker 1/2" valve. I got that replaced, and then looked into drilling my horns…

So I read this article about it and all. They said that the holes from the factory are normally 4mm. My 4a horn had a 4mm hole, but the other 2 horns only had a 3mm hole in it. I am guessing that they were special ordered that way for some reason by BNSF? The article said not to drill larger than 8mm. I decided to meet in the middle and go with a 6mm.

Needless to say, I’m not sure what exactly done it, either the larger hole in the horns or the 3/4" valve or both, but it defiantly has more of a punch to it!!!

I’m in love :smiley:

Thanks to Curt S for the great deal on a high quality, professional grade valve!

2

“Sounds” like it should be SICK!!! Any pics of the Mod?

3

^ No, I didn’t even think about it. It’s pretty straight forward though. 6mm drill bit and have at it! lol

4

Thank you Sir.

5

so you just take the horn off the manifold and drill?

6

ugh dont ruin a good horn…

7

That’s it. But don’t get shavings in it!
:cool:

8

Looks like you need to take off the back cap and diffuser ring so you can drill the intersecting hole. Isn’t that the case? Nobody ever mentions that…

9

^ The hole on the inside is much bigger that 4mm. I just drilled the outside and it made a significant difference.

10

Ahhh I see. I just looked at Curt’s pictures again.

11

I still don’t see the need. Engineers that designed these horns designed them the way they are for a reason. Making the air inlet holes bigger can’t keep their tones the same and definitely won’t make them sound better.

But it’s not my expensive horn to experiment on and possibly ruin :rolleyes: To each their own

12

^ FYI - They can and sometimes are ordered with larger and/or smaller holes depending on the customer. They do keep the “same” tone, and they “do” sound better IMO. If you haven’t heard a set of modified K’s in person, then you shouldn’t knock it!

13

I’ve never heard of MP sending out horns with larger inlet holes to railroads. If it truly makes them louder, they would be breaking FRA regulation in doing so. I’ve known them to increase the air inlet holes ever so slightly on number 5 bells occassionally to make them stand out a little more in a chord (meaning it does change the tone).

I never said someone couldn’t do it to their own horn and I’m not knocking it, if that’s what someone wants to do, then go for it. I’m just stating facts about it.

Find a Chessie K5LA or even possibly one of the brand new ones that MP is putting out and blow it around 100 PSI if you want to hear one sound best.

14

So it’s a 1/4" hole that’s a big hole. I have a 4a bell that has a little less than 1/4" but more than an 1/8"

15

i understand drilling out the inlet hole on the bottom where it bolts to the manifold. havent really understand the other place to drill out…