valve recession is posable  but highly  unlikely with a y blocks. cam  and lifter wear as well as rocker and shaft wear,rven with some oil at spill tubes, indicates some oil is getting to some rockers and some valve train.. tho with todays oils from rebuild to high miles and heavy valve springs some seat and valve recession is posable

It's been my understanding valve recession was usually or at least often associated as a result of the use of unleaded gasoline, esp. with high speed highway use and/or heavy load operation. In addition to providing anti-knock properties to gasoline the addition of tetraethyl lead compounds to motor gasoline provided some protection to valve seats at high temperatures.

I'm a little hazy on which engines were particularly prone to this problem, Ford (and others) used stellite seats or good steel on some engines (from the 50s thru 60s) some engines didn't need them? But some engines were notorious for sunken valves, designed for leaded gasoline and operated into the unleaded era.

Are Y-Block heads known for soft steel in the valve seats? Leaded-gasoline wasn't the only choice back then either, seems to me Amoco gasoline was specifically sold as an unleaded choice long before TEL was banned for automotive use.

I had valve recession in the 312 in my Bird (mileage unknown).  All seemed ok when I started out on a coast to coast trip.  By the time I got to Oregon, the car was not  idling good.  Worked the carb a little bit and it didn't help.  At speed it ran fine.  When I got back I started looking into things and found the valve gap was  off  (tight).  Redid the valves and it idled ok.  This was the first time I'd heard of valve recession.  Over the next winter got the correct heads for the car (it had later heads) and had a valve job done (hardened seats installed).  Next cross country trip everything was fine (except for the oil leak)


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Paul, that's "interesting", although probably not so interesting at the time.

This is getting a little off the beam from the original topic, but it is lubrication related, sort of right? Was this something evident you could see, or maybe with a straightedge? - I don't know, but wouldn't the valve stems be variable height across the head, maybe higher on some or several cylinders?( probably exhaust)

I stressed a bit about this because I did a few cross country trips before ever pulling the valve covers. When replacing the rockers/shaft/pushrods, valve guide seals & valve springs etc, the valve stem heights were all perfectly equal, but the valve spring installed height was out of spec and required various shims to get them to the correct installed height. I'd suggested hardened valve seats to the feller who "rebuilt" the engine, but I don't know if that happened. I doubt it.

In reference to hardened valve seats.  I have owned at least a dozen classic cars in my lifetime.  I love working on older engines. With few exceptions, I built a new engine for each car I owned.  The question of whether to install hardened valve seats has come up numerous times.  The logic is always that gas without lead will beat out the seats.  Some heads were beat up so bad by the time I got to them I had no choice. Others, like my current engine were pristine. 

I once owned a "G" code 406 Galaxie and a couple of 427 powered cars. Back then I bought boxes of lead additive to keep them running.  Today, I use Florida high test pump unleaded in my classic cars.   I hold the compression to about 9 to one. I time my engines correctly and they don't knock.   Since they started adding alcohol to the gas, I have not experience any damage from unleaded gas in any of my engines.  My current machinist agrees. He advised me not to install new seats in my Y-Block heads.  Keep in mind that I only drive my cars on nice days and to cruises.  If I was to build an engine to make a cross country trip, I would install new seats.  If nothing else, it would make me feel better.

new seats in eczG heads is a big risk as there is. very little cast left to hold them in place.in propane and natural gas engines you need stelight valves and seats.
I have herd from a number of machine shops that the alcahaul additives  that are in our gas helps.a easier solution is small amount  of engine oil in the gas at every fill, like 2 ounces.
  the so-called hardened seats in small block fords is heat the heads and quench them, looks good but rather question the hardness

I agree with FL-PHIL. Hard seats not necessary on lightly loaded, low speed engines.
Except I've started using Stabil 360 lately and I've always added some type of top end lubricant to the gas every so often out of habit.

"FREE SAMPLE"

Thats all I use on my engines, that stuff works good.  My 56 would normally get 3 weeks before the humidity here would result in separation of ethanol and fuel in the tank.  I started using the Stabil 360 and I can go a good 7 or 8 months without separation but the gas does get weak.

I also toss a bottle of Redline lead subsitute as well as my engine is original from '56 and I do plan on a complete rebuild with harden seats but my grandfather drove this car hard though foot always on the floor and it still running but lead gas was as far as i could tell was still avaliable in the early 1980s at some stations so maybe that is what saved this engine.

1956 Ford Fairlane Town Sedan - 292 Y8 - Ford-O-Matic - 155,000 mi

I think it's wise to go with hardened exhaust valve seats while the engine is being rebuilt. I know that "G" heads can crack between seats, but I have no direct knowledge of that occurring while installing hardened seats. I suppose it has much to do with the condition of the heads and who is doing the work. Having to baby it while driving can be stressful and takes the fun out of the experience. If in doubt, ask the man who knows. His name is Ted.

I've seen seats come loose and beat the piston, cylinder and head.