The first message here, on the forum, concerning my Mazda 3 since 2007. I really like the car and I did not have any problems with this, other than this: cylinder 1 currently has the smallest clearance of the 2.95 mm pusher valves. The rest of the cylinders are in second place.
After a small search query, I found more stories about the machines on which the smallest buckets were installed. But then I discovered that there are several "underground" methods for increasing the life of the cylinder head before proceeding to a complete revision. For example: for another car brand, I found that there are guys who slightly shorten the tip of the valve and are still happily walking (yes, this can damage the hardened tip). Another of the more elegant solutions I have read about is the use of market ladles with even smaller sizes.
Of course, I am fully aware of factory restrictions, and it is not recommended at all, but in comparison with a VERY expensive version of the cylinder head it's interesting! And in my case it's even free. I can let my friend make a 2.97 mm bucket at 2.96 mm. He can do it very accurately. And I can remove the camshaft and replace the buckets myself.
Now this means that the valve will be set 0.05 mm deeper into the cylinder head. Is it bad (or not bad)? I looked at a lot of photos of naked heads of cylinders with valves (naughty me ..), and my educated guess is that in metal there should be at least 1 mm of useful additional depth?
On the side of the note, for those who wonder why on earth this car is already on its smallest valves for demining: it's a Mazda that works on a gas LPG and Mazda did not install hardened valve seats ... And since I went out guarantees they will not do anything. I was hoping to reach 102,000 km. So, I would save enough money because of the cheaper LPG to justify the complete replacement of the cylinder head and still have free money. But at the moment it seems that I will finish at around 63,000 km. Each additional 0.05 mm will give me about 12,000 km. So, to get to the mark of 102,000, I probably need a final bucket of 2.75 mm
The available buckets