I always use all the parts in the full rebuild kit including the Welsh plugs. However, since I started using the USC, I've not found any debris in either Welsh cavity. Custom tells me to keep doing it, but it's probably moot.
Also, always take hold of the throttle shaft and force it sideways to test lateral play. If I have a lot, I won't use the carb because it won't tune properly. It's not usually the carb body that's worn out, but the shaft brass. If you have other parts carbs, you can sub in shafts that may make the fit tight again.
When I was buying carbs off eBay, I'd always ask the seller to test for throttle shaft lateral play. If I got the carb and it had play they went back or I got a refund. One seller balked and said he didn't understand what I was asking for in his defense, but eBay reviewed the conversation and sided with me.
Kevin
Also, always take hold of the throttle shaft and force it sideways to test lateral play. If I have a lot, I won't use the carb because it won't tune properly. It's not usually the carb body that's worn out, but the shaft brass. If you have other parts carbs, you can sub in shafts that may make the fit tight again.
When I was buying carbs off eBay, I'd always ask the seller to test for throttle shaft lateral play. If I got the carb and it had play they went back or I got a refund. One seller balked and said he didn't understand what I was asking for in his defense, but eBay reviewed the conversation and sided with me.
Kevin