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seat recession

Discussion in 'Norton Commando Motorcycles (Classic)' started by comnoz, May 15, 2019.

  1. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    I have had a few questions about the status of my non-symetrical cam.

    Since installing the Fullauto head and prototype cam in my bike I have been chasing the exhaust valve adjustment. It's been loosing clearance regularly.

    After my last trip to LOP last fall the valve clearance had closed from .008 to .002 and the leakdown was very high. I could hear air from the exhausts.

    I finally got it down to check it out. Here is what I saw.

    Serious exhaust valve recession.
    P1020764.JPG
    This was a new head a little over a year ago. The exhaust seats had not been touched.

    Here is the seat. The valve stem height had increased over .060 so the spring pressure was very low.
    P1020790.JPG
    So new powdered nickel/iron seats and new exhaust valves are installed. The intake seats are seats I installed when I did the big valve conversion. They looked perfect.
    P1020774.JPG
    I bolted the head back on this evening and rechecked the leakdown. The results were very good.
    Now a few good trips this summer should confirm my suspicion that the seats were simply not up to the job.
    But then the other possibility is something about my cam profile is causing excessive seat wear.
    And this is why I am holding off on doing up a batch of non-symmetrical cams at this time.
    Jim
     
    Jerry Doe and nortriubuell like this.
  2. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    Well, that's something to look forward to if it is the valve seat material.
    Those are the KibbleWhite parts you sent me long ago...

    IMG_5784.JPG

    There is a lot of tricks on your head pic.
     
  3. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    At least Norton valve seats are easy to replace.

    I like no head gasket and no oil leaks. Now if the valves don't leak I will be golden.
     
    Nater_Potater likes this.
  4. Madnorton

    Madnorton VIP MEMBER

    Joined:
    Jun 9, 2008
    Jim,

    What amount of miles has caused this wear? I didn't suffer any valve clearance close up with the standard cam, 7K miles on the PW4 cam now and nothing to indicate any issues with this cam either, both used with the FA head.
     
  5. gortnipper

    gortnipper VIP MEMBER

    Joined:
    Nov 11, 2013
    :confused:
     
  6. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    PM on the way.
     
  7. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011
    OK, I'll bite....PW4?
     
  8. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008


    I went and looked at records. Close to 12,000 miles with the Fullauto head. Most of them at 80mph +. Jim
     
    Last edited: May 16, 2019
  9. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    Were you using unleaded fuel instead of leaded fuel?
     
  10. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Yes, there is no leaded fuel available around here unless I buy race fuel.
    But that has been the case for many years.
     
  11. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    It's all unleaded everywhere I've been as well and has been for decades.
    There is lots of ethanol free available on the west side of the continent.
    The days of leaded fuel are almost as far back as polyglass tires.

    Glen
     
    Nater_Potater likes this.
  12. Madnorton

    Madnorton VIP MEMBER

    Joined:
    Jun 9, 2008
    Pete Williams latest design, huge lift and runs with radiused followers.
     
  13. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Basically the same as a Webcam 86c when run with radius followers.
     
  14. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    There are still a couple of places advertising ethanol free fuel here in Pueblo.

    Funny thing is I know the guys who deliver their fuel and they tell me ethanol free fuel has not be available from our distributor for years....
     
  15. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Ive been using this site when travelling.

    https://www.pure-gas.org/index.jsp?stateprov=BC

    You can click on the state list and get a page showing your state.
    They show 4 places with ethanol free in Pueblo.

    There are all kinds of stations with at least one pump labelled ethanol free, but as you say, how do you really know?

    I would say that the Chevron Supreme 94 Octane we can buy here in BC is ethanol free. I use it in anything that will have fuel stored over winter, motorcycles, weed trimmer, lawnmower etc.
    It does not create crud in the carbs, the engines just start and run fine in the spring. This is without stabilizer.
    The one that truly amazed is a 15 HP Merc outboard which is stored at our cabin.
    We use this twice a year, spring and fall, about 3 days each time, just trolling which isn't great for a motor.
    Every spring it starts up as soon as the gas gets into it. Always last year's gas which has some mixed in from the previous year as we do not use up an entire tank each year, we just add now and then. We are doing things wrong using the old fuel, but with the Chevron Supreme in there it has worked without a hiccup for 18 years now.

    When gas with ethanol first appeared years ago, not knowing about the carb problems, I left gas with ethanol in a couple of engines over winter. What a mess!

    Glen
     
    Last edited: May 16, 2019
  16. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Yeah, the stations here in Pueblo are listed on Puregas also...it is not necessarily up to date.
    I buy race fuel for my dirt bikes and my small engines. It stays good over the winter just fine. I add about a gallon of race fuel to the streetbikes also if they are going to be setting.
    It works good -however my experience with storage additives has not been good.


     
  17. KiwiNeill

    KiwiNeill

    Joined:
    Jul 25, 2011
    I,ve just checked the valve clearances on my low 200 serial 2017 Fullauto.
    Minimal adjustment over 7200 miles with Webcam #312, very slightly loose on the inlets, exhausts OK. Both Black Diamond inlets and exhausts set at recommended 0.006" with hand cut + 0.060" inlets.
    Stock AN springs were set at 1.200" height with 100 lb seat pressure according to Jseng1 chart.

    Not fussy with fuel either, has run with most unleaded types from basic e10 through to Aral 102 without much difference in logged fuel consumption or noticeable power changes over this period and has done its share of fast long distance running.
    Petrol of choice is BP Ultimate 97 with no ethanol but only because it,s available down the road from me.
     
    Last edited: May 18, 2019 at 2:28 PM
  18. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011
    I think I have one of those somewhere :)
     
  19. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Mine is a little earlier than yours. I think it is #8
     
  20. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Hi Jim,

    Nice to see you are posting again.

    For those not knowing how valve seat recession comes about (myself included), I snipped this paragraph out of an article:

    "Valve set recession is the erosion of the valve seat causing the valve to slowly sink deeper and deeper into its seat. Without the protective lead coating or hardened inserts on the exhaust valve seats, the intense heat (650 'C / 1200 'F) and the constant hammering effect of the valves opening and closing causes iron deposits from the valve seat to become micro-welded to the valve edge as it closes. When the valve opens again, some small amount of metal from the seat will be ripped from that seat. Left alone, this continual tearing away of metal particles will result in the exhaust valve digging a deeper and deeper hole for itself into the head. Eventually, the engine will break down and require to be overhauled. Valve seat recession is only a problem for the exhaust valve seats since they run at much higher temperatures than the intake valves. "

    Have you inquired with Fullauto what seat material was used?

    For your consideration, according to an expert opinion at SBI (Nashville, TN), powder metallurgy seats are not the best choice for performance engines because of work hardening that occurs as they age. "They start out at 25 Rockwell C and can end up at 40 Rockwell C after they age. That’s too hard (for a performance engine) and may cause the seat to shatter.”

    Actually, PM seats may end up at 44-45 HRC according to some reports.

    Here is another piece of information to consider:

    "The valve seats on stock heads as they come from the factory are induction hardened. This is a process where the valve seat surface is case hardened by applying a heated coil to the seat for some time. The result is a hardened surface in the seat area that is resistant to VSR. Most experts believe that typically, the depth of the induction hardened material runs approximately 0.030" deep. Fortunately for us, we've recently discovered that the General has done a little better on our heads. When one decides that they will fit oversized exhaust valves in their heads, one must be careful because some this hardened area will have to be cut. If the valve is large enough and the cut is deep enough, this hardened material may be completely removed. "

    Were exhaust valve seats fitted at the Norton-Villiers factory induction hardened?

    If your cam profile is fierce, you may want to consider using high nickel alloy seats if the PM seats fail. They should be selected having an initial hardness of 30 RC. According to reports, high Ni alloy seats will not work harden as much as PM seats. Values of 35--37 HRC have been reported.

    Regards,

    Knut


    Sources:
    http://www.intense-racing.com/VSR/VSR.html
    https://www.enginebuildermag.com/2018/03/understanding-todays-valve-seats/
    https://www.enginebuildermag.com/20...-selection-for-high-performance-applications/
     

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