I have read that when rebuilding the head on a JD 420 you should install hardened valve seats due to the unleaded gas we use today. I also understand that the 420 did not have replaceable valve seats. Would you have a machine shop machine the head to accept the hardened seats and install them? Would you do the intake valves also or just exhaust?
Jerry
Hardened Valve Seats
Re: Hardened Valve Seats
Yes, done by a machine shop. If the existing seats show much wear, I would have both done, otherwise, they usually only do exhaust.
Lavoy
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com
Owner and moderator www.jdcrawlers.com
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