Sactownog Posted October 31, 2019 Share Posted October 31, 2019 so I am rebuilding a 1953 Dodge 230 flat head 6 I have heard the Seats should be switched out to HARDENED SEATS, my engine has ran on 91 in California (kamifornia) and while I am rebuilding this engine, I am replacing the valves, valve springs, but am going to leave the seat's alone as they look fine after a few thousand miles and with 36k miles on the car (engine miles i dont know how many are on it), the seats look good. need a good cleaning, valve job, then good to go. but what are your thoughts? leave the seats as is if they look good or replace them, deck block and get seats that are more modern aka hardened? personally, I am leaving the seats and doing a valve job as the vehicle does not drive very often. (to shows and back to garage) Link to comment Share on other sites More sharing options...
Matt Harwood Posted October 31, 2019 Share Posted October 31, 2019 Leave them alone. The need for hardened valve seats is grossly over-stated. Your engine never needed them before--why would it need them now? Lead was never intended nor designed to "cushion the valves" so taking the lead out hasn't really led to massive valve seat issues like everyone predicted when the switch to unleaded happened. The flip-side is that a hardened valve seat is an insert and not part of the block, so there's a greater risk of failure down the line or if they aren't installed correctly. If they're in good shape, leave them alone. I'll presume you're not racing the car or planning to run it at high speeds across the desert while towing a trailer, so the stock seats should outlast us all regardless of what kind of gas you're using. And keeping the stock seats will save you money! 6 3 Link to comment Share on other sites More sharing options...
Sactownog Posted October 31, 2019 Author Share Posted October 31, 2019 32 minutes ago, Matt Harwood said: Leave them alone. The need for hardened valve seats is grossly over-stated. Your engine never needed them before--why would it need them now? Lead was never intended nor designed to "cushion the valves" so taking the lead out hasn't really led to massive valve seat issues like everyone predicted when the switch to unleaded happened. The flip-side is that a hardened valve seat is an insert and not part of the block, so there's a greater risk of failure down the line or if they aren't installed correctly. If they're in good shape, leave them alone. I'll presume you're not racing the car or planning to run it at high speeds across the desert while towing a trailer, so the stock seats should outlast us all regardless of what kind of gas you're using. And keeping the stock seats will save you money! I GREATLY APPRECIATE YOUR RESPONSE, I was planning on leaving mine in. I like to get more info from folk's out there with opinions as to why or why not to do things. Mine really just need to be cleaned up and they should be good. I am next debating on the valve guides, but those may be ok with the new valves already. 1 Link to comment Share on other sites More sharing options...
edinmass Posted October 31, 2019 Share Posted October 31, 2019 Want to know how many pressed in seats fail to stay put and pop out when the motor gets hot pulling a long hill? Leave them alone. We fix lots of botched jobs from people who have no clue as to what they are doing. If your that worried about it, run modern stainless valves........very expensive........and add a bit of two strok oil to the tank on each fill up. All still not necessary. Stock is the best option. 2 Link to comment Share on other sites More sharing options...
keiser31 Posted November 1, 2019 Share Posted November 1, 2019 (edited) Chrysler products already had hardened seats in those days. There was no unleaded gas at that time. Edited November 1, 2019 by keiser31 (see edit history) 3 Link to comment Share on other sites More sharing options...
trini Posted November 1, 2019 Share Posted November 1, 2019 If on cleaning up you find that you need to replace any then replace with hardened seats. Otherwise leave them alone. Check the valve springs and valve guide 1 Link to comment Share on other sites More sharing options...
avgwarhawk Posted November 1, 2019 Share Posted November 1, 2019 Seats...stay away. I had a seat fail in a head that has them installed before I purchased the car. Both heads were boat anchors. Sourced new heads. Link to comment Share on other sites More sharing options...
DavidMc Posted November 1, 2019 Share Posted November 1, 2019 In addition to the reasons already stated, machining out the block or head to take the seats can weaken a casting already weakened by internal corrosion leading to cracks especially where the valve are close together. I had to discard a 1929 Packard block due to multiple cracks that developed between the seat inserts. Replacing the machined out material with the inserts does not compensate for the material removed and the stress from the interference stress may further increase the risk of cracking. Don't do it apart from being unnecessary it can be detrimental. 1 Link to comment Share on other sites More sharing options...
c49er Posted November 2, 2019 Share Posted November 2, 2019 All the MoPar flatheads already have hardened Stellite exhaust seats. Leave it as is...it will be just fine. After 50 years of driving these old MoPars and never an issue with mine...use this and all the advice already given! 1 Link to comment Share on other sites More sharing options...
Bloo Posted November 2, 2019 Share Posted November 2, 2019 (edited) If the seats are bad and recessed enough you MIGHT have to replace them. If the seats aren't bad, don't replace them until they are. The fears about unhardened seats are overblown in anything EXCEPT drag racing, dump trucks, towing, speedboats, etc. As Keiser31 and c49er mentioned, they ARE hardened in a 53 Chrysler product. Falling out or coming loose has been a recurring problem in engines with inserts, either factory or aftermarket. The machinist has to really get the job exactly right or it might fail. Why risk it until the seats are shot and you have no other choice? If i had recessed seats, I would look into installing slightly oversize valves to get the valve heads back up where they belong, rather that having inserts installed. Edited November 2, 2019 by Bloo (see edit history) 1 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted November 3, 2019 Share Posted November 3, 2019 (edited) Your car came with hardened valve seats and replaceable valve guides, unlike cheap engines like Chevrolet V8. Chrysler also used more fine thread fasteners, better quality materials etc. Unleaded or low lead gasoline was all they had when your engine was designed in the thirties. It was made for gas of about 65 octane. You don't need to worry about unleaded gas. If you want be pernickety you could add a little Redex, Marvel Mystery Oil or your favorite upper cylinder lube to the gas. Today's gas is very dry compared to the gas of the thirties forties or fifties and a little oil can double the life of the valves and rings. Edited November 3, 2019 by Rusty_OToole (see edit history) 1 Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 3, 2019 Share Posted November 3, 2019 3 hours ago, Rusty_OToole said: Your car came with hardened valve seats How did they harden the valve seats locally? Link to comment Share on other sites More sharing options...
Rusty_OToole Posted November 3, 2019 Share Posted November 3, 2019 (edited) 8 minutes ago, Spinneyhill said: How did they harden the valve seats locally? They installed Stellite inserts for the exhaust valves. All Chrysler built engines had this feature including flatheads and early hemis. I don't know when exactly they dropped it. In the seventies they went to flame hardened or induction hardened seats. You can just see the insert in this cutaway view of the engine (left valve). You can also see that it has valve guides, adjustable valve lifts, flywheel held on with hardened fine thread nuts and bolts not cap screws, insert bearings, full pressure lubrication, floating oil intake and possibly a few other niceties not seen on other low priced car engines of the time. Edited November 3, 2019 by Rusty_OToole (see edit history) Link to comment Share on other sites More sharing options...
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