King 607f valve bumpers

[Matt4576]

I have a Besson 737 which is a relabeled King 607f. I want to replace the valve bumpers but they seem to be an odd size. I measure the diameter of the seats in the bumper plate at 7/16" (.219"/5.5mm). The bumpers I see available are either 3/16" or 1/4". I'm guessing that what is in there is a 1/4 bumper that was forced into the seat. It's a pretty tight fit. Does this sound right or is there a purpose made replacement for this horn?

TIA - Matt

[Crazy4Tbone86]

Did you mean 7/32” for you measurement?

[Matt4576]

Oops, yes 7/32".

[Crazy4Tbone86]

The diameter of the rubber bumpers should be slightly larger that the slot on the cork plate (bumper plate). Many people glue them in but, with the appropriate-sized bumpers, it is not necessary. My recommendation is to buy a cord of bumper material in a size that is 1/32 to 1/16 too large and install it the following way:

1. Remove the cork plate from the rotor housing and remove the old bumper. It it was glued, you might need to do some scraping to get it completely clean.

2. DO NOT cut the bumper material before installing! Insert a small bit of one end of the bumper cord IN A VISE and tighten it so that you can stretch the cord. When the vise is tight, stretch the cord so that it is considerably thinner than its original diameter. Place the bumper plate over the stretched cord and it should pop over it. Slide the bumper plate as close to the vise as possible. When you un-stretch the cord, it should be held firmly in place. Sometimes you can slide the bumper plate even closer to the end of the cord after removing it from the vise. Trim the bumper material with a razor for a flush fit.

3. Repeat on the other side of the bumper plate. Finally.....trim the contact side of the bumper material for the proper alignment of the valve.

[Matt4576]

Thanks Brian, that helps a lot!