FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Bolted to Floor on July 27, 2014, 01:18:06 AM
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OK guys, I need more of an education. Dealing with the exhaust seats before and after the switch from leaded to unleaded fuel. Somewhere along the way, the fuel changed. New cars after this point got different exhaust seats. No way all of the older cars got upgraded.
My 69 F250 with a 360-2V never had the exhaust seats changed. I bought it from my grandparents with 145K in 89. Rebuilt the motor at 150 and drove it more than 60K miles through the late 90’s. I never noticed any difference. May have not been smart enough to notice either!!
With unleaded fuel, why are the different exhaust seats required, or is it more like a recommendation? ???
I ask because I want to make use of some C6AE R heads that I have. I already have the FPA's with the CJ flange and should seal with these heads. I don't want to spend a lot of money on them, porting and CJ size valves are out also. My other head options are D2's and the 390 GT's. Somewhere in the distant future, I will upgrade to aluminum heads, just not sure when.
Thanks in advance for the answers.
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You have to go pretty far back to find a head without hardened valve seats. By the late 1950s most everything had replaceable hardened seats due to increased compression and unleaded fuels.
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Unleaded fuel dates to the mid - late '70's, not the fifties. Any domestic gasoline before this change had pretty high levels of tetraethyl lead in it, which also drove the high octane ratings of gasoline from that era. Any domestic vehicles made before this had unhardened exhaust valve seats. As the lead in fuel promoted cooling of these seats, it's not uncommon for these older engines to burn exhaust valve seats when using unleaded. The cure was switching to a hardened seat, typically done with a Stellite coating on the seat/valve, which better resists the high temps.
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Unleaded fuel dates to the mid - late '70's, not the fifties. Any domestic gasoline before this change had pretty high levels of tetraethyl lead in it, which also drove the high octane ratings of gasoline from that era. Any domestic vehicles made before this had unhardened exhaust valve seats. As the lead in fuel promoted cooling of these seats, it's not uncommon for these older engines to burn exhaust valve seats when using unleaded. The cure was switching to a hardened seat, typically done with a Stellite coating on the seat/valve, which better resists the high temps.
One correction about lead, it does not cool the valve, it lubricates the valve and seat preventing the transfer, on a microscopic level, of metal from seat to valve face. It is also not uncommon for a much cooler running intake seat to "sink" as does the exhaust seat from lack of lead as a lubricant. Burnt valves are not a direct result of unleaded fuel but may burn as they are no longer in firm contact with the seat and can't cool properly.
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I pulled a 69 390 truck engine apart last year that had spent its life up here in Canada.The exhaust seats were gone....as in destroyed..
I pulled the iron heads apart that were on my 427.They had about 17,000 miles on them.They also were destroyed...No damage to the valves but the seats are history...
I then yanked the heads (67 289) back off my 289 roller engine in my 67 but they were fine.Its a very low mileage engine but I cant put seats in it as its got 1.9 and 1.6 valves and there is just no room left..
I have aluminum heads for the 427 and I will just have to use additive in the 289 for now...
My opinion and general understanding of the damage unleaded fuel can do has been severely updated....
Cory
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The only engines I have ever had an issue with is late 50s down. Running an engine lean and advanced for power will smoke seats, but even my old tractors from the 30s, 40s and 50s have no issues. Valve rotators help a lot with wear also.
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None of the engines are run lean or are over advanced...My flat head Dodge tolerated the un leaded much better than the FE's did...
As far as I know the only FE head with any thing close to a good exhaust seat are the D2 heads...
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Man I have run FE engines for 200,000 miles in service trucks with no big issues, wonder why? They smoked some but did not rattle or buck under load, which was constant with a ton of pipe and threding equipment in the tool boxes.
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It s my understanding that hardened seats started in production about 1972 , and up and the leaded fuel lubricated valves and seats . And by the way leaded regular gas stayed at the pump til 1988 .. Bud
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It s my understanding that hardened seats started in production about 1972 , and up and the leaded fuel lubricated valves and seats . And by the way leaded regular gas stayed at the pump til 1988 .. Bud
We had a form of leaded gasoline in Colorado until 1994.
Josh
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I believe lugging an engine affects it more than the lack of lead; I have seen many heads that are fine without hardened seats, mine and others. Truck engines seemed to be hit the hardest as they would be loaded worse than car engines. If I were to run old heads, if they had good seats I wouldn't change them...just my opinion and experience.
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When I got my '62 Galaxie back in 2005 or so, it had what I was told was an original motor in it. Later down the line I pieced together it was a '64 era dealer replacement shortblock with OEM '62 top end on it...anyway, never had hardened seats in what I'm pretty sure were OEM '62 factory heads. There was a jug of lead additive in the spare tire well and the prior owner told me to use it religiously, to which I immediatley forgot. I had a valve job done shortly thereafter and the machine shop asked if I wanted hardened seats installed. I forgot about the jug of lead additive and figured, "hell, if they aint sunk already, I'm good!" and didn't have the hardened seats installed. About 10k miles later, the motor started feeling pretty tired. It had 90k on the odometer. When I tore it down, it was pretty worn and ready for a refreshening. Oh, and half the valves were sunk into the heads...some worse than others. I'd have the hardened seats installed in whatever heads you choose to run.
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Thanks for the information and the education. I went Googling to forums far away and found pretty much the same results as here. Some have had issues and others have not. Several mentioned the use of a lead additive, but it could separate in the gas take if it sets a while. I will look into the cost of adding the hardened exhaust seats to the price of a valve job and just see where the pricing goes.
All of this hinges on if the guides can get away with knurling or need to be replaced. If the heads need too much work, then the whole idea may get scraped anyway. :-\
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A couple of comments on exhaust seats, seat recession and the need for hard seats. First: some heads under certain conditions will "work harden" on their own and is usually related to use. Around town at low rpm, low load and low heat in the exhaust will not usually need hard seats. The seats will surface harden similar to "case harden" pieces done by a heat treating company. High speed highway driving for long periods of time and/or heavy loads where exhaust temps are high valves will almost always sink into the heads. I have done heads where both intake and exhaust were sunk and both sets of seats needed replacement and I have done other sets of heads [EDCs-C1s-C4s-C6s-C8s] where the exhaust seats acted like they were induction harden similar to what the factory does for use with unleaded gas but not as deep. D2 heads, from early 72 and later used factory induction hardened seats. FWIW, Every set of heads I do gets hard seats, not worth the worry of sinking valves, loss of compression and having to do the job again.
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Interesting....the 390 heads that I had with the sunk valves were the factory heads on a 69 F-250 4x4..Truck was from Alberta and I don't know its story..
My 427 Heads were C8's with CJ valves.90% of the miles on them were Mountain hwy's,climbing mountains and any other long winding hill I could find.Engine lives at 3000-4500 rpm.Even if I was city driving I didn't lope around....
I will put seats in the heads and use them on another project..We have had unleaded here since the mid 80's.....Cory
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Maybe it is the fuel used? I always run good gas, the little extra in using good fuel saves in mileage and repairs in the long run. Tune ups last longer and less sludge in the engine.
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What happened with me goes along with RJPs statement .I owned a 66 f250 with a nice 390 without hardened ex seats .I used this truck to pull a welding trailer and a car trailer that weighed 4500-5000 with car .Long story short my exhaust seats receded .(c8ae heads ) I had hardened seats installed and no more problems .Bottom line if you use a vehicle for serious pulling or for long intervals of driving exhaust valve seats are cheap insurance . Another possibility are d2 truck heads with their induction hardened ex. seats .I don't know if the these are as good as having hard seats installed though .Doug
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Maybe it is the fuel used? I always run good gas, the little extra in using good fuel saves in mileage and repairs in the long run. Tune ups last longer and less sludge in the engine.
That one always makes me laugh. Good Gas. You get what ever comes out of the pump. ::)
Gasoline does not cause sludge.
This causes sludge.
Poor or no PCV system.
Running the engine to cold.
Water in the oil.
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One correction about lead, it does not cool the valve, it lubricates the valve and seat preventing the transfer, on a microscopic level, of metal from seat to valve face. It is also not uncommon for a much cooler running intake seat to "sink" as does the exhaust seat from lack of lead as a lubricant. Burnt valves are not a direct result of unleaded fuel but may burn as they are no longer in firm contact with the seat and can't cool properly.
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I didn't say it cooled the valves, I said it promoted cooling. We're saying pretty much the same thing, different words.
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Maybe it is the fuel used? I always run good gas, the little extra in using good fuel saves in mileage and repairs in the long run. Tune ups last longer and less sludge in the engine.
Whether the tank truck says Shell, Chevron, Mobil, or Beacon, 7-11, or Mom and Pop, they all fill from the exact same spigot at the refinery. Doesn't mean there aren't differences, because there are...in the additive package, not in the base fuel. The additive package is put in to spec when the truck is filled.
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The guy that built my engine (I have c4 series heads) put in CJ size intake valves. His name is Doug Anderson out of Albuquerque and he has 40 plus years experience and is considered by many to be quite the expert on FE's. (Ask Bud, bn69stang)
He said that it usually isn't an issue if the head is well seasoned. Like RJP said, they self harden with leaded fuel. He also told me that the c4ae-6090g heads didn't really have enough seat to put in hardened seats. He advised me to use a lead additive if I was concerned, and I do.
Correct me Bud if I'm wrong, at least according to what I remember Doug telling me.
Dave J
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Yeah Dave he s told me the same thing , he is really old school and been an fe guy forever , 67 comet 427 , and he also has an original t -bolt , and i really like dealing with him but there is things his shop just does nt do .. but he is 70 now and im feeling he will retire in the next year or so .. Bud
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Hello gentlemen, reviving an old thread here.
I'm about to start a build on a 410 using CJ heads. This engine will be going in a 1989 F-150 2wd short bed and will be used as a daily driver.
My questions are: Is there enough material in the CJ heads to install hardened exhaust seats? Also, it seems I read somewhere that installing stainless valves alleviates the problem of metal transfer from seat to valve--any truth to this?
Thanks.
Bruce
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My experience is similar to RJP . Many '60s heads have no seat recession at all despite years of unleaded use. When I see that , I don't change them. In the early '70s "new" production Ford heads were notorious for exhaust seat recession until induction hardened versions were introduced. Seat recession was rampant in '72 on 351C/400 2V heads.
Randy
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Running stock valves in a stock 68 SBF head I noted some seat recession in the exhaust pockets. On the 351C-2V heads that I updated to stainless, bronze guides, etc - zero recession despite racing on pump gas for several years. Pump fuel has become so much crap that I now rather pay $9.50/gallon for VP 110 leaded in any race car/fun car with higher HP and is abused.
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I can't say I've ever had seats sink in any FE I've ever ran, but I put hardened exhaust seats in my old 390 that I used in my '68 F-250 Highboy (25 years ago), only because it was going to be used to pull/haul heavy loads. I've seen sunken valves plenty of times in small blocks from the early to mid '70s; sometimes so bad I'd swear the exhaust wasn't flowing any air!
The heads I used for my Highboy were C4-G heads, and yes they lose quite a bit of support when cut for seats, but the guy who did the work was an old Ford guy, and he just made sure the interference fit was tight enough. Those heads are in use on my '65 Galaxie now, with nothing more than a light valve lapping before putting them on, so 25 years of use now with no issues.
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Thanks guys. I'm kinda on the fence about which way to go but I'm leaning towards having the seats installed.
I have a pretty competent machinest who has installed them in some early 460 heads for me and they're doing just fine. I'll show him the CJ heads and see what he thinks.
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FEs are tricky because a good portion of the replacement seat is poorly supported. I too subscribe to cast iron work hardening. My 68.5 CJ heads have zero seat recession. Of course they began life on leaded and then were subjected to unleaded after 74 ( or so). I am leaving them "as cast". Since it has been relegated to "sunny day" or race track status , I can always add some race gas or lead substitute without having to take out a loan. LOL
Randy