1.5" exhaust values?

Royals65i6

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I have a 1980 cylinder head that I have been working on for a while now, and I can't find any information about whether or not to add hardened valve seats after increasing the exhaust value opening. I assume when increasing the diameter of the exhaust value opening from 1.38 to 1.5 I would be eliminating the hardened seats that were already there. How much over 1.5 can be removed to make room for new seats?

Thanks for the help
 

chad

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there's even mixed opinion on need to harden.
Opinion tilts toward 'Yes" if having long periods of hi revs (me - heavy off roadin, others - racing).
And "No" if used on the street under normal DD.
 

Royals65i6

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Is there any worry of removing too much metal to fit the hardened seats in and accidentally damage another part of the head?
 

bubba22349

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The mid 1970's and up heads have factory hardened seats to deal with the then new mandated unleaded fuels. Your only opening up the seat another .012 - .013 total or .006 per side. In my opion you don't really need to install the hard seats in these late model heads. Yes it can cause problems when cutting out the head in order to fit the hard seats in I would only do this in order to repair a damaged seat, plus these late heads have a tendency to crack in some places like in the center exhaust ports. Good luck (y) :nod:
 

CNC-Dude

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Actually, 1.380" to 1.500" is just shy of an 1/8", or .120" which would be .060" per side. Also the bowl area will need to be enlarged as well for the larger valve or you won't really gain much even with going to the larger valves.
 

chad

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CNC-Dude":32nsi5wk said:
Actually, 1.380" to 1.500" is just shy of an 1/8", or .120" which would be .060" per side. Also the bowl area will need to be enlarged as well for the larger valve or you won't really gain much even with going to the larger valves.
shrouded.
Hey, Dude...
the avatar comes thru now...
 

CNC-Dude

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I just made a new one, it's also a t-shirt i made as well. I'll find a link for it if you're interested. Thanks
 

bubba22349

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CNC-Dude":2p8l7enn said:
Actually, 1.380" to 1.500" is just shy of an 1/8", or .120" which would be .060" per side. Also the bowl area will need to be enlarged as well for the larger valve or you won't really gain much even with going to the larger valves.

Yep your right CNC-Dude, I must have still been half asleep yet! :rolflmao: :nod:
 
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