Farm Equipment - Hardened valve seats or not?

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Hardened valve seats or not?

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=209932
Printed Date: 01 Feb 2026 at 11:49am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: Hardened valve seats or not?

Posted By: J&J
Subject: Hardened valve seats or not?
Date Posted: 01 Feb 2026 at 9:14am

The machine shop has the head for my 1952 CA. They say the seats look good and there's no reason to install hardened valve seats. If I do it I want to do everything right. Valve job (new valves), guides, springs, keepers, resurface the head. What's the consensus on hardened seats, at least on the exhaust side?

Replies:

Posted By: jaybmiller
Date Posted: 01 Feb 2026 at 9:21am

hmm... don't you NEED them because there's no lead; in gas anymore ? I know it's not a high performance muscle car engine but...gee, while it's all apart......

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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water

Posted By: steve(ill)
Date Posted: 01 Feb 2026 at 9:24am

i have rebuilt several of the smaller AC engines and never put in a new seat..

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Like them all, but love the "B"s.

Posted By: WF owner
Date Posted: 01 Feb 2026 at 9:27am

The biggest reason people change to hardened valve seats is because there is no lead in the gas. Lead used to be beneficial for the valve seats. Unleaded gas has been available since the early 70's. It has been the only thing available for decades.

This is just my opinion, but chances are you are never going to use your CA for much hard work. Why change to hardened valve seats, if your machinist says they are in good shape. It has worked this long with the original seats (which already be hardened). Why change them now?

Posted By: DrAllis
Date Posted: 01 Feb 2026 at 11:29am

Well, a WD45 already had steel (hard) exhaust seats from the factory. I'll bet the CA does too.