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1.5" exhaust values?

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Royals65i6
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1.5" exhaust values?

Post #1 by Royals65i6 » Thu Mar 28, 2019 1:07 pm

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

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chad
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1.5" exhaust values, how big to go, harden seats?

Post #2 by chad » Thu Mar 28, 2019 2:48 pm

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.
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), 250, NV 3550 & DSII to B transplanted, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", tool boxes, etc. Seeking: Hydraulic gear motor for Koenig pto. chrlsful@aol.com (413) 259-1749

Royals65i6
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Re: 1.5" exhaust values?

Post #3 by Royals65i6 » Thu Mar 28, 2019 11:52 pm

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

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bubba22349
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Re: 1.5" exhaust values?

Post #4 by bubba22349 » Fri Mar 29, 2019 10:14 am

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 :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: 1.5" exhaust values?

Post #5 by CNC-Dude » Fri Mar 29, 2019 4:41 pm

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.
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chad
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Re: 1.5" exhaust values?

Post #6 by chad » Fri Mar 29, 2019 5:32 pm

CNC-Dude wrote: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...
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), 250, NV 3550 & DSII to B transplanted, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", tool boxes, etc. Seeking: Hydraulic gear motor for Koenig pto. chrlsful@aol.com (413) 259-1749

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Re: 1.5" exhaust values?

Post #7 by CNC-Dude » Fri Mar 29, 2019 6:48 pm

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
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bubba22349
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Re: 1.5" exhaust values?

Post #8 by bubba22349 » Fri Mar 29, 2019 9:28 pm

CNC-Dude wrote: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:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

CNC-Dude
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Re: 1.5" exhaust values?

Post #9 by CNC-Dude » Fri Mar 29, 2019 10:26 pm

We're all human and do it from time to time. LOL
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