So long story I will condense. Years back I bought a used set of heads and ported them, had new seats installed. They sat in the shop for years in open air on my workbench and had a lot of surface rust. Dust and moisture isn’t a good mix. So I had new valves installed and the heads surfaced, guides checked out. The shop faced the valves and cut the seats. I just looked them over closely before work yesterday, and noticed a few valves protruding visually more than the others on bot heads. My thought is those few seats were in better shape than the others and weren’t cut as deep to be finished. It bugs me. So the real question is , are the seats hardened steel, or surface hardened that can’t be cut to much? Thanks. Edit: so much for the condensed version
Yes, hardened seats are machinable. They have to be machined after initial installation. As to your question are they hardened? Guess you will have to check the original machine shop slip. As to the various installed heights, could be the seat heights, the amount taken off the valves, or a combination of both. Look at the edge of the valve face and see if the thickness is equal.
At one point you were able to buy cast iron seats but I found the in the late 90s all the seats sold were hardened. Even intake seats. There are multiple materials and hardness’s offered depending on application. If the seats are shiny and didn’t rust like the rest of the head most likely there hard. And if the shop only had grinding equipment there are different stones that need to be used and they may have got lazy and just ground until they had a seat and moved on. As mentioned I would check your installed height. The rockers have enough adjustments to compensate but the spring heights need to be double checked.
If the seats were brand new, and you just had new valves also installed, then even touching up seats and valves should not show large differences in the seated depth in the chambers. If there are large differences then I'd question what was done to remove so much metal off seats and valves, or if any sitting deeper are new.
I may not have been clear. The seats were installed 12/13 years ago and the heads sat in the shop since. Last year I took them into get valves and have them resurfaced. I’d never looked at them without the valves in them back then, never occurred to me. But as mentioned they had a lot of surface rust. I just ***umed the seats may have had some pitting they had to cut more out than the few that look like that are not sitting as deep. I’ll get some time today and and take a few valves out and see what’s up.
I believe you need to get a machine shop with modern equipment to equalize all of the valve heights. There may be more to the story but with different valve heights, the airflow will be different and the rocker arm geometry can be off. Measure the amount of the stems sticking out of the guides as a beginning to see what may have happened.
No, I understood what you originally said. But seems odd that if the seats were all new then, that they'd sit different heights now? Unless they were so badly rusted it took a heck of a lot of machine work to get rid of pitting? Personally I think if some seats took that much to clean up, the machine shop should have just replaced those particular seats again so they weren't down to their last grind right out of the gate.
That’s what I was thinking. (Replace them if an issue). Didn’t get a chance to get in the shop today, had fun with my oldest daughters car. Those heads can wait until tomorrow.
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