hardened valve seats not need for nailheads

Discussion in ''Da Nailhead' started by dennis h. pater, Apr 3, 2009.

  1. dennis h. pater

    dennis h. pater Active Member

    Hey guys,
    In case some guys haven't heard, maybe this will save you a little
    time and money. I read that nailheads don't need hardened valve seats
    for the gas nowadays because the blocks and heads were cast with a high nickel content in the iron, so they're ok. That's what i read anyway.
     
  2. Lucy Fair

    Lucy Fair Nailheadlova

    Nice starting post:bla: .
     
  3. dennis h. pater

    dennis h. pater Active Member

    hey kacpur, I had a 67 Riviera just like your picture. Light green, it had a
    430 engine, not a nailhead. good car.
     
  4. DaWildcat

    DaWildcat Platinum Level Contributor

    Dennis, it's a "it depends" situation I'm afraid. The same has been said about the later big & small blocks too.

    From Greg Gessler's website:

    Devon
     
  5. 66electrafied

    66electrafied Just tossing in my nickel's worth

    I asked the same question earlier when I was rebuilding my Nailhead. From what I was able to learn, from members on this board as well as some articles I was able to find, was that Nails don't really need hardened seats because of the smaller size of the valves and the flow characteristics of the heads. Part of the reasoning is that most of these cars aren't daily drivers anymore and rarely get more than a couple thousand miles put on them in a year. However, if one was into racing these engines, it might be a suggestion to put in hardened seats.

    The machine shop that did my heads also told me that putting hardened seats is difficult because the seats are "awfully close to water", and the risks of cracking the cast are good. They also advised against it.

    However, the later series of big-block Buicks would probably better served with hardened seats. I had a '67 Wildcat with a stock engine that I rescued from a barn that had about 80,000 miles on it. When I first got it running again it had a steady needle on a vacuum gauge. After 4 years of driving (in summer) that engine had deteriorated somewhat, and I could see that the seats were probably starting to deteriorate because the vacuum gauge needle was starting bounce. (A sure sign of poor valve seating) These engines had huge valves and a wedge combustion chamber; - more forgiving on bad gas (low octane) than the Nail was, but worse heat dissipation characteristics, requiring hardened seats.

    I guess it all really depends how much and how hard you're planning on driving the car, and what kind of gas you're planning to run.
     
  6. Lucy Fair

    Lucy Fair Nailheadlova

    Nailhead in my Rivi likes 98 octane,yummy yummy.Valve seats are still fine:pray:

    :3gears:
     
  7. ahhh65riv

    ahhh65riv Well-Known Member

    I have never heard of anyone ever having issues with running unleadded with unhardened seats on a nailhead- original or with resurfaced/re-cut seats. However, I have read and heard of plenty of issues with those that had hardened seats installed.

    Just as a thought...Maybe if I were a machinist that made my living and fed my family on machine work, I bet I might have a different opinion to convince a customer to spend the extra $$$ to have hardened seats installed on nailheads too.:Dou:

    Erik
     
  8. 66electrafied

    66electrafied Just tossing in my nickel's worth

    Most of the machinists that I've talked to hate to do them, and will charge a fortune for the job. They'll spend an hour trying to talk you out of the idea because the chances are good that they'll either crack the head, or put it in too loose. It's generally the purists who read alot and have bottomless wallets who get them done.

    Everything that I've read indicates that "the jury is still out" on the topic; - it seems some engines benefit from hardened seats, and others don't.
     
  9. doc

    doc Well-Known Member

    In Houston back in the 60s, there was a place that specialized in repairing engine blocks,heads,any cast iron.... they had ovens set up on natural gas that heated the heads for 24 hours and then a man would arc weld new beads in the valve seat area with cast iron rods,,,, then back into the ovens for a stress releiving heat soak.... then the machine shop cut new seats into the repaired heads.....
     
  10. Fragzem

    Fragzem Well-Known Member

    Equivalent of US 93 octane.

    That's what I use.
     
  11. John Codman

    John Codman Platinum Level Contributor

    The jury is not still out on hardned seats in big nailheads. Do not do it. As someone earlier said: "The seats are awfully close to the water" (which helps them run cooler). I ruined a perfectly good 425 head attempting to install hardened seats. And we were really careful. I now carry a couple of bottles of lead substitute (which I probably don't need either).
     
  12. hjsonnie

    hjsonnie '51 Henry J '72 Skylark

    Just finished installing my nailhead in the chassis of my Henry J. Was thinking of running 100LL aviation fuel mixed with 93 unleaded. I was told that the 100LL had a high lead content. My heads were done by Greg Gessler and I thought he recommended easing in the seats for awhile, with leaded fuel or equivalent if possible.
    Don
     
  13. 66electrafied

    66electrafied Just tossing in my nickel's worth

    I would not suggest running avgas in that engine. Avgas is formulated to be stable at altitude, the octane rating is calculated differently than car gas, and has totally different burning properties than car gas. The lead content is different too; - here again it's designed for different operating temperatures, shock cooling, altitude, and a lot sloppier and lower compression engine. When I did my pilot's licence a number of years ago, I asked an AME whether or not I could run avgas in the car. He said if I tried it it would blow the engine to bits because it's a lot more volitile than regular gas, and that even a mixture of pump gas and avgas would result in detonation damage.

    You're better off using toluene or a lead supplement than avgas.
     
  14. John Codman

    John Codman Platinum Level Contributor

    100LL avgas does contain lead; it's not all that low in lead either. The "LL" does stand for "low lead", but what it really meant was that it is low in lead relative to the old 100/130 avgas that it replaced. I gotta disagree with the post that said you will blow your engine to bits with the stuff. Avgas is designed to withstand higher temperatures then autogas (mogas) without vapor lock. It does not have additives to improve cold weather starting. It is absolutely uniform regardless of where you buy it. It also has a very long shelf life. If you use it, you should not add Stabil or any of the additives that you might use for long-term storage of gasoline. 100 LL is not designed for low-compression engines. That was the now obsolete 80 octane avgas. Normally-aspirated aircraft engines that use 100 LL are usually about 8.5:1 compression. Many are fairly heavily turbocharged.
    A likely result of using 100 LL in significant quantity will be shortened exhaust system life and possible lead fouling of spark plugs. The lower your engine's compression ratio, the greater the lead-fouling problem is likely to be. Although it is true that aircraft piston engines are set up (a lot) looser then our automobile engines, they operate at much higher Brake Mean Effective Pressures (BMEP) then do our liquid cooled V8s. Air-cooled aircraft engines also run a hell of a lot hotter. I have no problem mixing in a little 100 LL with my unleaded 93 mogas. It won't hurt your engine.
     

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  15. CameoInvicta

    CameoInvicta Well-Known Member

    I agree. I know of many a hot rodder who have ran an av gas blend without problems. This was also a highly discussed topic at another forum I used to be apart of and the consensus was the same; it's fine within reason.


    And as far as hardened seats, not needed. I've run about 13k miles in 11 years on a rebuild without hardened seats. Runs like the day it was new.
     
  16. Schurkey

    Schurkey Silver Level contributor

    The guy that told you that is not to be trusted.

    I used to run 100LL in a 10,500 rpm motorcycle engine. Worked great. Smelled great. It did lead-foul plugs; and it did build up combustion chamber deposits bad enough that I had problems with using ordinary premium pump gas after awhile. BUT--100LL works fine in ground-based vehicles. Perhaps not as well as a "racing" gasoline. Still, it's quite satisfactory except of course for spewing poisonous lead all over creation.






    EVERY division EXCEPT Chevrolet brags up the "high nickel" cast iron; as if it were something only their division had. Pontiac, Olds, Buick, and Cadillac lovers all seem to think their favorite division "invented" nickel in cast iron.

    If nickel in iron made a difference for valve seats, GM wouldn't have hardened the exhaust seats starting in '71 or 72, in preparation for catalytic converters and no-lead gasoline beginning in '75. The fact that GM DID have to go to a hardening process for exhaust seats should be evidence enough that nickel content alone is NOT enough to prevent seat recession.

    You may get lucky. You may drive the vehicle so little as to not erode the seats. You may not use heavy throttle which will accelerate seat wear. The small diameter exhaust valve on the Nailhead certainly doesn't hurt! In the end, even GM knew that without hardened exhaust seats--the warranty claims after the sale would cost more than just using hardened seats before the sale.

    Nickel in iron makes a difference for bore wear because the iron is harder and more wear-resistant. Valve seats are another story because the process that erodes them is different from what erodes cylinder walls.
     
  17. 322bnh

    322bnh Well-Known Member


    That is the most senisible post on valves and seat wear that I have seen. I have some 264/322 heads that have severe recession of the exhaust AND the intake valve seats...probably form repeated valve jobs and running hard on hot Texas roads. And these heads probably never saw unleaded gas. I have installed seats in some of these severely eroded heads with good results. If the heads have good seats I use stainless exhaust valves.
    I have a 51 F-1 and when I rebuilt the flathead 90,000 miles ago the machine shop talked me out of replacing the seats since there were seat inserts already installed. Well the original seats were not hard enough since I had to adjust the valves every 15,000 miles (glad I installed adjustable lifters). Anyhow when I could adjust no more I replaced it with a 264 Buick engine (used engine with unknown valve/seat) I'll just run it until when/if it has problems.
    Willie
     
  18. harleyriv

    harleyriv Member

    I had hardened seats installed in my 425 Nailhead in 2003....No coolant problems since then and no need to carry additives.

    Harley
     
  19. 66electrafied

    66electrafied Just tossing in my nickel's worth

     

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