I am glad Roger sent me his caps as this has helped convince me to increase the diameter of my buttons. One of his caps had a larger rim diameter and my button was too easy to press in. I did have a slightly larger size that I installed in that cap, so I was able to complete his set. Unfortunately, I will have to go back to the original style seal with a larger button. Back to the instructions…
Step 3. Polish the slide shaft using Mothers Metal Polish or another similar polish. I use a micro fiber cloth and push a corner of the cloth into the well and then turn the slide. After that consider installing the optional nylon washers. There is a wide side of the washer and I recommend installing the wider side face down. The washer is to prevent metal-to-metal contact if the rod is unable to be stopped by the button. If the depth of the shaft hole to the bottom of the button exceeds about 44.80 mm, the slide will be stopped by the washer instead of the button. Normally, the button will stop the slide, but there have been numerous cases where slides have cracked due to due to metal-to-metal contact. This could be because the button cracked or totally failed. If the slide shaft depth to the bottom of the button is too deep and the rod is unable to contact the button, you will also have metal-to-metal contact. The nylon washer is insurance and I actually prefer using it as a stop instead of the button because the load is spread across a larger area with the washer. I have determined the ideal depth of the shaft to the bottom of the button is about 44.70mm. If you have that depth, the washer and the button are probably going to make contact, which is ideal. The load is then spread across a larger area, the washer and the button. Also, installing the washer allows the slide to fully open, so I don't see any downside of using it. It is totally up to you if you want to use it or not.
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Step 4. Make sure the slide will operate very smoothly. You should be able to drop the slide into the cap and hear a thud with no resistant. Also make sure the tiny vacuum hole is open. Push a paperclip into the hole to insure it is open.
Step 5. Prepare arbor press area. Have everything you need arranged for easy access. See the picture below for ideas.
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Step 6. If you want to measure the hole with calipers, the size should be about 25.50mm. If you don't have calipers, place the button on top of the cap and see it the edge will go into the hole at least ¼ to 1/3 of the way. If not, use a craft knife and run the blade around the hole ONE time. Hold the knife at a 45 degree angle to create a bevel to make it easier to push the button into the hole. Then, place the button in the hole and recheck to see if it will go in ¼ to 1/3 of the way. If not, trim again, but only one time around. It does not take much at all to make the hole big enough. Old Fogey gave me this tip of using the craft knife and it works great.
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Step 7. Now you are ready to add epoxy to the groove. Only a small amount of epoxy is needed. Do not put too much or you will plug the vacuum hole. Mix only enough JB Weld Plastic Bonder for one button at a time. You only need enough to fill the groove. Use a toothpick to mix the epoxy and then work a small amount into the groove. Then use rubber gloves and run your finger around the groove to remove excess epoxy. Go to the next step quickly and get the button pushed in because we want the epoxy to settle around the button. Nothing sticks very well to acetal, but this epoxy does pretty good. It will definitely create a seal and help hold it in place. Old Fogey prefers using Gorilla glue but if you choose to use that stuff, be very careful because it expands a lot. I found that epoxy bonds better to acetal but it is your choice. Install the seal.
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Step 8. Make sure the button is even all the way around as it sits in the hole. Then place the button press tool on top of the button. Use the curved edge for the first press. The curved edge allows the button to give a little as you press it in. Once the button is in, turn the press tool over and press again to make sure it is fully seated. Wipe off any excess epoxy if it comes out the top. Then, verify the vacuum hole is open. One way to do this is to inset a finger over the hole inside the cap and then suck air through the shaft hole and then remove your finger to see if the pressure changes. You could use a vacuum pump too. I also run a paperclip through the hole and if any epoxy is on the paperclip. If so, you used too much epoxy. You may be ok, but double check to see if air freely flows. If it is blocked, simply knock out the button using a large flat head punch and do the procedure over again. It is easy to clean up the mess and start over so don’t get upset, you will be fine. If you damage a cap, I will have individual caps available for about $10.00 each.
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Step 9. Place the cap on a flat surface, right side up, so the epoxy can settle and cure.
Step 10. Repeat for the rest of the caps.
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. They are currently getting a bath, so we will have to wait a day or so to get started on this adventure. I want to go through all the steps required to replace the buttons and use this thread to show people how to do it. Maybe some future expert can create a video. The kit will include four buttons, four seals, four 1mm nylon washers for the slide shaft and a button installation tool, You may question why include the four nylon washers and to make a long story short, install them because there is no downside in doing so. The slide will open completely with these installed and they will prevent metal-on-metal contact. More on these later but for now, let's take a good look at our carb tops:
