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Another factor to consider is effect of the machining of the area around the valves to receive the seats. If the valves are close together and the block is already weakened by years of internal corrosion it can reach the point where the machining will further weaken the block and it will crack between the inserts. The new inserts do not compensate for the removed material and may in fact introduce addition stress due to the interference fit.
I had this happen to a 6th series block and it eventually cracked in 3 similar locations. I finished up having to replace the block. Needless to say I would not fit hardened valve seats and the charts posted by OD shows that they are unnecessary in most cases.

THe valve recession chart is overly conservative at best. I would say the speeds along the botom scale need to be have about 30 to 40 mph added to each mark.

I will once again cite examples of my own personal experience:

88 2.0 ranger 2800#'s/74 hp = 39.
80 225 six dodge pickup 3300#'s/145hp = 23
73 chevy impala 350 v8 ?
48 Indian 600#'s/40hp = 15 unless we add my 185# ass = 20.

Above is list of only 3 out of about a dozen vehicles owned at least 10 years to as long 42 years and operated at my own personal use. Mostly in the 60 to 70 mph range and often at 80 mph sustained. Vehicles with as high as 80K to 190K miles.

NO valve recession. In the case of the Indian extremely minor but that is a very short service life engine to begin with. None of them with hardened insets.

Valve recession is only an issue on engines that are operated at or very near maximum engine rpm. Vehicle weight has nothing to do with it.

Solid lifters can have some minor contribution to the recession.

For anyone trying to decide on hardened valve seats:
For any given engine do some research on any commerical, industrial, Ag or medium to heavy truck applications of the same engine. In some of those cases the hardened steel seats may have been used in the same era of that engine.

For normal passenger car and lite truck use and assuming sustained speeds of up to 80 or 90 mph the hardened seats are overkill AND run the risk of the insets comming loose.

Hardened steel seats as Insurance???? Well, who is going to write u an isurance policy if those seats come loose and tear up a head and a piston?????

DavidM in post #11 above gives good advice and sound reasoning.

"To use hardened exhaust seats or not", that is the question.

As a point of reference, starting in 1972, Pontiac induction hardened the exhaust seats on ALL of their heads. Other GM divisions and/or manufacturers may have done the same. Induction hardening does not induce the stress that fitting a separate hardened seat does. Obviously, no Packard had induction hardened exhaust seats.

However, if you drive a car with an engine that does NOT have hardened seats and you drive it at sustained 80+ MPH, which is easy to do today, at least on the long drives in the Western USA Interstates and similar, you WILL "pound down" (actually grind away) the exhaust seats because today's unleaded gas does not provide the lubrication between valve edge and seat like the old leaded gas provided.

As usual, you pay your $ and you take your chances.

Craig

So then why not induction harden the seats for the Packards instead of cutting and machine the heads/blocks for inserts??? Not real familiar with the induction process but it in someway involves heating the seat very localy. A kind of cyanide or case hardening process. Probably only available at very sophisticated speed shops.

And yes, i can imagine many of u cowboys out west in the wide open spaces can often run thru dessert at 90 to 110 mph for maybe 75 miles ata time and 110* ambient or hotter. THe hardened seats a good idea in that case. But that is an exceptional situtation and not what would be considered normal operation thru out the rest of the world.

Why not induction harden the seats instead of cutting the head for inserts????

PackardV8 Quote:

A quick google search indicates that induction hardening is only done by OEMs. I couldn't find any automotive machine shops, sophisticated or otherwise, who do it. They all either cut the existing induction hardened seat (if the hardening is deep enough) or install a separate hardened insert seat.

PackardV8 Quote:

I found this explantion:
"[induction hardening] is a process where the valve seat surface is case hardened by applying a heated coil to the seat for some time."
here:http://www.intense-racing.com/VSR/VSR.html

PackardV8 Quote:

Yup, pardner! Yippe ki-yay...!

Craig

I've not yet performed any kind of upgrade for the use unleaded fuel in any of my pre-1975 cars (and don't use any lead additive), but had researched the matter years ago, for when that day might come.

WRT the loss of lead additives, the problem of valve seat recession is limited to the exhaust valves. Under higher operating temperatures and in the absence of the lubricating effect of tetra-ethyl lead, the problem is not one of abrasion, but material transfer. That is, the combined high heat and rapid hammering action of the valve results in material being transferred from the exhaust valve seat to the exhaust valve face, where it is eventually shed.

With leaded fuel, valve seat recession is usually only found on high mileage vehicles, but with unleaded fuel, the process occurs more rapidly. Yet, the issue may very well be over-hyped for vehicles that only see show/cruise use.

To counteract the effects of unleaded fuels on valve recession, one must look to materials that will reduce the transfer of particles. However, rather than flirting with all the risks of machining the block to accept inserts, and provided the valve seats need nothing more than refacing/reseating, why not simply install stainless steel or Stellite-faced exhaust valves?

Stainless steel exhaust valves have pretty much been the standard by the better engine rebuilders for the last 10-15 years.

Owen_Dyneto Quote:

So, who makes SS valves for any year Packard as an off-the-shelf deal?

Craig