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Valve Seats Question

aspekt9

Proven Member
344
4
Dec 25, 2005
Boston, Massachusetts
I got my head back from the shop, the guy said it was one of the worst heads he's seen and whoever did the machine work on it before, did an incredibly shitty job, and used a hand drill or something on the seats. He said that in order to fix it he had to cut the seats decently deep and the valves will sit a little deeper in the head than usual. He said if it was a racehead, he would have had new seats put in it, but that for a street build I should be fine.

My question, is what kind of adverse affects, if any would I see from running this head with the valves a little deeper in the head than normal? And what exactly does having the valves deeper in the head do? Does it affect compression?
 

Clutch GSX

15+ Year Contributor
347
1
Nov 28, 2006
Denver, Colorado
It will lower your compression a little bit but the main thing to worry about is the stem height. The hydraulic lash adjusters (lifters) can only account for so much variation before the geometry of your valve train is out of whack. The builder should know what to do to fix this. You can ask if he is going to measure base to tip and tip the valves if it is out of spec. If he doesn't know what you are talking about then you may want to have the work done somewhere else.
 

aspekt9

Proven Member
344
4
Dec 25, 2005
Boston, Massachusetts
I'm pretty sure he'd check the stem height and cut them if necessary. He's very well known around the Bay State area, and has built countless race heads for a lot of well known guys on the newengdsm forums. I was just seeing what the disadvantages are of the valves sitting further in the head, but I don't think it will be a good deal, I'm only looking to push 350HP at most.
 
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