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Discussion Starter · #1 ·
Over in the old school world of cast iron heads & leaded fuel, there was a phenomenon that existed where the constant contact of a hardened valve and head (valve seat) actually caused the recession of the valve seat over time. The lead in the fuel acted as a lubricant to ensure a "cushion" between the valve and seat as they opened and closed.

Fast forward to unleaded fuel. When the powers that be determined that leaded fuel was detrimental to the environment, they removed the lead. In order to keep cars' valves from sinking into the head over time, they applied a hardening process to the valve seat. Viola- Problem solved. However, in the cast iron world, cutting of the valve seats to install large diameter valves actually machines away the hardened part of the heads. This is most notable on the Grand Prix's 3.8L engine, which there are a ton of upgrades for (some running 10.9 and better). Link here.

Fast forward again to aluminum heads. Aluminum is, of course, lighter and softer than cast iron. It would appear on the surface that they might exhibit the same problem. My question is this- Are valve seats in aluminum heads hardened by any means- And, more importantly, do those of us with 3L valves and the resultant machining work have to worry about the same phenomenon over time?
 
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Wow, that's an interesting question.
Hope we aren't affected, but it seems to be a possibility. I'm going to be watching this one before I get the heads done...
 

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looking at the heads... it doesn't seem to have any kind of material change from the combustion chamber to the valve seat.... so i'm going to say no on the hardening....

which brings up the next point.... and yes i'm sure over time it will degrade... but the new question is HOW MUCH time does it take...

if it takes 10 years... who cares.... even 5 years.... but anything less than 5 years and i would starting thinking about doing something about it.... i'm not a metalurgy expert, but i dont' see how you could harden just a small area of an aluminum chunk... perhaps pressing in some kind of steel liner, but then the steel liner itselft would eventually go into the aluminum head..... so again we are back to the drawing board....
 

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After some thought, wouldn't the roller rockers and lifters restrict the valves seat pressure? The issue of seat failure is completely dependent on the pressure that the valve places on the seat when it lands. As long as there is enought pressure to make a seal and not too much pressure to stress the valve seats, everything else should be kosher.
 

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Discussion Starter · #5 ·
Puck- The metal is heated with a coil to a specific temperature to harden it- Something along the lines of restructuring the metal at the atomic level with a certain amount of heat energy. I don't think there is any visible sign of hardening.

Trevor- Along those same lines- OHV engines with lifters, rods, & rockers would have the same effect, yet they suffer from the problem. OHC engines just have a "nominal" seat pressure because the system is always tensioned against the cam lobe? This is an interesting question, and the only thing I foresee happening with ours is that due to the softer metal, we may have a little "spring" to the valve seat. This may cushion the blow.

Or, with time if we suffer from VSR, we get an improper valve seal, as the cam lobe only lets the valve receed so much before the nominal lift (0) part of the cam keeps the valve, spring, and retainer in place. :ugh:
 

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I think you guys are worrying too much! LOL Truth is the valve guides are of a different metal then of course the aluminum, however I don't know what it is or if its hardened. I will say that I did a set of heads with over 250,000 miles on them and we found NO wear, and vthe valves sealed fully because we used them to measure the cc's for a base, and that was done with both sand and water and were of the spec listed by Ford 44.5 +-1.5cc. All were 44.xx. These were from a 95 contour.

Bottomline, DanG enjoy your car and stop worrying! ha ha
 

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Originally posted by: Kinger
I think you guys are worrying too much! LOL Truth is the valve guides are of a different metal then of course the aluminum, however I don't know what it is or if its hardened. I will say that I did a set of heads with over 250,000 miles on them and we found NO wear, and vthe valves sealed fully because we used them to measure the cc's for a base, and that was done with both sand and water and were of the spec listed by Ford 44.5 +-1.5cc. All were 44.xx. These were from a 95 contour.

Bottomline, DanG enjoy your car and stop worrying! ha ha
It's in his nature to worry about his car ... it's his only child :biggrin:
 

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Discussion Starter · #8 ·
Jesse-

Valve seats, not valve guides. Look here for pics of a cross section- I'm speaking of the round edge in which the valve actually makes contact with the heads- Not the guide for the valve stem.

Stop worrying... Feh... :rolleyes: Why don't you just tell me to run my baby without oil?!
 

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BOO YAA Just got off the phone with my machinest......Steel hardened seats in all aluminum heads and are NOT effected by P&P work, and will not recess into the head over time.


DanG quit worrying and start driving that baby like ya stole it!!! :)
 

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Originally posted by: Kinger
BOO YAA Just got off the phone with my machinest......Steel hardened seats in all aluminum heads and are NOT effected by P&P work, and will not recess into the head over time.


DanG quit worrying and start driving that baby like ya stole it!!! :)
The valve seats would not be effected at all by P&P work, but it certainly could be effected by removing metal from the seat when you cut the seat for the new valves. What matters here is that exhaust seats are a fully hardened piece of metal, meaning that it's hardened all the way through by being put into a type of oven and held at temperature to harden the part through to the center. Exhaust seats will wear evenly and not "sink" into the head unless the head has a major defect of some sort.

BTW, most car metal pieces are not fully hardened. Rather, they are surface hardened where the hardening only goes a few thousandths of an inch below the surface before exposing softer metal. Such is the problem when trying to regrind camshafts...
 

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Discussion Starter · #13 ·
Brad:

Exactly my concern. From Jesse's post, we surmise the following:

-Duratec heads have hardened steel valve seats
-Steel valve seats are hardened all the way through
-Cutting said valve seats for new valves (3.0L valves in 2.5L heads) removes some of the seat, but since they are a fully hardened piece of metal, cutting affects nothing long-term.

Problem solved?

<u>Kinger: Please verify!</u> Again- It's not the P&P work that I'm worried about! It's the cutting of the seat for the larger valves!

PS (Brad): Exactly the concern of the folks on the GP boards- Their heads are heat treated after casting- Their hardened valve seats are only a few thousanths of an inch deep into the head. Cutting for larger valves actually removes the hardened metal.
 

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Digging deeper after getting the email from Terry, I wanted to get his input about fitting the 3.0L valves to the 2.5L heads.

Read This!

Basically, it comes down to how the work was done. Jesse, I think that you should investigate this with your machinest next time you talk.
 

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Originally posted by: DanG
Brad:

Exactly my concern. From Jesse's post, we surmise the following:

-Duratec heads have hardened steel valve seats
-Steel valve seats are hardened all the way through
-Cutting said valve seats for new valves (3.0L valves in 2.5L heads) removes some of the seat, but since they are a fully hardened piece of metal, cutting affects nothing long-term. WRONG!!! They are NEW LARGER seats to accomodate the 3L valves

Problem solved?

<u>Kinger: Please verify!</u> Again- It's not the P&P work that I'm worried about! It's the cutting of the seat for the larger valves!

PS (Brad): Exactly the concern of the folks on the GP boards- Their heads are heat treated after casting- Their hardened valve seats are only a few thousanths of an inch deep into the head. Cutting for larger valves actually removes the hardened metal.


In bold above: we weld a tack to the current seat which causes them to shrink and we pound out the seat, cut in the larger valve from the aluminum head and replace with a LARGER HARDEND STEEL SEAT to accomodate the larger valve.

Please guys don't be making assumptions were half azzing things, if I gave the impression that the old seat was used I apologize. My M/C estimates that these will last for 250-300,000 miles.

*EDIT I'll add this to the list of services to avoid future confusion. Thanks!
 

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Originally posted by: Kinger
Originally posted by: DanG
Brad:

Exactly my concern. From Jesse's post, we surmise the following:

-Duratec heads have hardened steel valve seats
-Steel valve seats are hardened all the way through
-Cutting said valve seats for new valves (3.0L valves in 2.5L heads) removes some of the seat, but since they are a fully hardened piece of metal, cutting affects nothing long-term. WRONG!!! They are NEW LARGER seats to accomodate the 3L valves

Problem solved?

<u>Kinger: Please verify!</u> Again- It's not the P&P work that I'm worried about! It's the cutting of the seat for the larger valves!

PS (Brad): Exactly the concern of the folks on the GP boards- Their heads are heat treated after casting- Their hardened valve seats are only a few thousanths of an inch deep into the head. Cutting for larger valves actually removes the hardened metal.


In bold above: we weld a tack to the current seat which causes them to shrink and we pound out the seat, cut in the larger valve from the aluminum head and replace with a LARGER HARDEND STEEL SEAT to accomodate the larger valve.

Please guys don't be making assumptions were half azzing things, if I gave the impression that the old seat was used I apologize. My M/C estimates that these will last for 250-300,000 miles.

*EDIT I'll add this to the list of services to avoid future confusion. Thanks!
Thanks for clearing that up. I don't think that we ever assumed that you guys where ever half-assing it, but you have to beat us over the heads with facts. It was never stated that the seats where replaced. Knowing that they are is a great reassurance for those looking to get this work done. Thanks again for all the great work and information regarding this process!
 

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Originally posted by: FastCougar It was never stated that the seats where replaced. Knowing that they are is a great reassurance for those looking to get this work done. Thanks again for all the great work and information regarding this process!
From the GB spec sheet:

This P&P package will include the following:
2.5L P&P with 3L valves includes:

· Complete disassembly of old valves/springs
· 3 Dunk tank baths in cleaning solution
· Bead blasted
· Blown out to remove any foreign matter
· Spray coated with silver HEAD SPECIFIC paint for a BRAND NEW appearance
· BRAND NEW 3L valves
· 3L valves cut into combustion chamber
· Exhaust seats replaced with larger units
· Deck resurfaced
· 30 hours of hand porting of the intake and exhaust ports
· Complete assembly of valves, springs, and retainers
· 4 angle valve job on intake and 3 angle valve job on exhaust
· Flow tested at 8 different lift values with sheet
· Flow matching between all intake and exhaust ports to assure equal flow through each valve
· Wrapped in shrink wrap to prevent foreign matter from entering cylinder heads
I can see the confusion because it is replaced on BOTH the intake and exhaust, I'll change my documentation, originally we were going to leave the Intake alone but decided agansit it after the flow bench results :(

Thanks again guys!
 
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