Valve Seat inserts

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Originally Posted by CarlG

My only experience with valve seats: I had one come loose 600 miles from home. This was on an engine that had been built by a "reliable" builder in Southern California and only had about 3,000 miles since rebuild. (Not the only problem with that engine.)

My comment, for what it's worth, concerns both a rebuilt engine from a similar builder AND valve seats. First the valve seats. My opinion on what went wrong is that the builder ordered hardened seats that were too big and when they arrived, he fitted them to the block without checking them. Whether he realised what he had done when he came to assemble the engine or not, I don't know but it's hard to believe he didn't. When he installed the valves (standard Model A valves), they almost fell through the seats. They only seated at the extreme outside 1-2 mm. The engine could not be made to idle well (no wonder) and was noisy. The fact that within a few hundred miles, the bearings started to fall apart didn't help. The lady owner was on the ball enough to hear things going wrong in there so removed the engine and took it to another guy I recommended. He made new valves to suit, redid the bearings and a few other "little" things. The original builder has "retired".
My take away from her experience is that "improvements" sometimes are OK, other times .......... I have hard seats on only one of my six running engines ( a Burtz engine).