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Discussion Starter · #1 ·
I'm running a 1970 YH 455 block with number 15 heads with a Comp Cams 276ah - 10 cam. Comp Cams recommend using 995 - 16 valve springs which requires Machining of the valve seats on the heads to achieve the proper spring installed height. The Machine Shop is telling me that there's not enough for them to Mill the valve seats down without it being into the water ports on the head has anybody ran into this problem before? Looking for some recommendations?
 

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Sounds fishy to me, there's usually a lot of meat in the spring seats.

According to the few sources I found, the factory spring installed height is 1.600, and those Comp 995-16's show that they need an installed height of 1.700. That's only 0.1 deeper, assuming those figures are correct.

If by some chance they're telling you the truth, then one option would be to replace all the valves with the longer stem Ram Air IV valves, which are approximately 0.2" longer than others, then shim the springs as needed to make up the difference.
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You might also be able to use +0.050 "up" locks that let the retainers ride higher on the valve stems, but ONLY if they don't put the retainers too close to the rockers. I know PAC has these, and problably other manufacturers do as well.

Sometimes, shops will "tell you things" just because they don't want to do the work.

I dunno, anything's possible I guess but like I said, sounds fishy to me.

Bear
 

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Discussion Starter · #3 ·
Thank you for the info. I was told the stock height on my heads was 1.5 so they would have to mill it .20 to get the 1.7 for the new springs but I will have to verify that.
 
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