Author Topic: Hardened seats  (Read 280 times)

maxi426

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Hardened seats
« on: December 06, 2018, 06:11:30 AM »
I'm going to have a set of early 350 heads done to put on a 403. One local shop is really recommending hardened valve seats. The other, not so much. It's my understanding that 7a heads already have the seats hardened. If this is correct information, can the valve size be increased to big block size and still have enough hardened seat left to be effective? I don't have cores yet, so I'll look for "7a"s. if this will work. The car will maybe see 2000 miles per year. Should I even worry?

Aus78Formula

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Re: Hardened seats
« Reply #1 on: December 06, 2018, 04:38:49 PM »
See what cores you find then decide what they need doing.

langss

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Re: Hardened seats
« Reply #2 on: December 06, 2018, 05:03:20 PM »
Here is a link that explains Valve Seat Recession https://oldschool.co.nz/index.php?/topic/20751-valve-seat-recession-explained/
And Here https://www.enginebuildermag.com/1997/02/getting-a-good-seat-the-growth-in-the-valve-seat-insert-market/
My personal experience is without the Hardened Seats, Valve Seat Recession is  not an issue on a car that never see's any abuse. But if your planning on running it hard....Have the seats installed.

maxi426

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Re: Hardened seats
« Reply #3 on: December 06, 2018, 06:54:20 PM »
Is it a fact that the seats are already induction hardened on the 7a head?

olds403

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Re: Hardened seats
« Reply #4 on: December 07, 2018, 09:38:10 AM »
Once you do a valve job that hardened surface is gone.  I would not worry about it.
If you have to sleep better at night get seats pressed in.  No need to over think this.

Re: Hardened seats
« Reply #4 on: December 07, 2018, 09:38:10 AM »

via3d

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Re: Hardened seats
« Reply #5 on: December 23, 2018, 01:16:43 PM »
no guru but did a lot of reading on #7 and 7a heads and this hardened seat issue.

i am buying 7 heads at great price for a 403, was told they had hardened seats when in fact did not. I knew they didnt, and the owner wasnt deceiving me, he was just mis-informed.

--->>>>Yes the 7a heads have hardened seats.

7 = 1971 olds 350 heads
7a = 1972 hardened seats

of course dont confuse with
7A= mid 80's 307 heads
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now this whole thing about must have hardened seats.  for occasional or daily driver I find more real world experience indicates dont worry about it on pump gas. I read many in depth technical articles from gurus, racers, and metallurgists, and  "olds timers" (haha I like the pun).
Also, real world experiences indicate that the Olds are much less of a worry than chevys and such.... Olds didnt deteriorate/recess like chevys.
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Larger Valves:

yes of course you can go larger valves WITH Macine work and $$.  If your dropping that kind of money than just buy new SS valves and associated components for a coue bills more. BUT is it necessary for the gain to just go part wY? OR are you willing to go all the way with the heads... I have read you can achieve upwards of 100hp to go all out on heads. IF just machining for larger valve/seat: then you want to follow the ( same year same head ) spec for the W31 engines at 2"int/ 1.625"exh valves OR  the 2.07"/1.71" valves can be done with more machine  bowl work.

For a daily driver, according to many reads, not sure you will definitively see a butt feel difference with just larger valves put in - unless it is conjunction with bunch of other porting work and $$ done to heads, intake, & exhaust...Which eadily can approach a grand $.

if you just go minimum for large valves only in heads:
You can spend $$ for dyno and get a cute piece of paper that tells you that you have a few more hp, ;) Lol...   not knocking it, i want want the same cute paper for my build(s).

AND must say also:  If you are willing to spend all out on #7a heads then why not go BB heads (Less machine & cost) pa or aftermarket for same ball park $$$  ??? 
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Watch for my new post, I am asking about stock 7 heads on stock 403.
~ J

Re: Hardened seats
« Reply #5 on: December 23, 2018, 01:16:43 PM »
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