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Head Modifications

Discussion in 'Rootes Racing' started by jdoclogan, Nov 23, 2020.

  1. jdoclogan

    jdoclogan Platinum Level Sponsor

    With Roy Stetina's #21 in my shop and some of the racing components from the 60s when Stetina raced. I was amazed at the following head modifications.
    upload_2020-11-23_11-54-24.png upload_2020-11-23_11-55-9.png upload_2020-11-23_11-57-34.png

    First off I did a Vizard modification (for #41 Sebring Alpine) taken from standard drawings that I shared here before. My grinding process ended with approximately 41cc of material removal per cylinder and somewhat vertical walls. In addition I ground and polished from the manifold side all of the inlet and exhaust channels.
    upload_2020-11-23_11-33-16.png

    The first Stetina head I found had a Vizard modification with more of a sloping grind out to a slightly increased perimeter. It also had ground and polished inlet and exhaust channels from the manifold and block side of the head. Note: water jacket preparation before head machining.
    upload_2020-11-23_11-36-8.png

    Then I find a significantly different modified head that came from the dozen or so heads I obtained. The machinist took the grinding all the way to the inside edge of the piston perimeter. It was sloped as well. Both the inlet and exhaust channels were ground and polished from the manifold and piston side. This made for a significant molecular flow increase. I'm thinking this was to accommodate a domed piston.
    upload_2020-11-23_11-43-1.png

    I would welcome any comments.
     
    Last edited: Nov 24, 2020
  2. jumpinjan

    jumpinjan Bronze Level Sponsor

    You didn't notice in last picture all the "squish" is gone...not good unless the engine is operating in high RPM band.
    An example of old school flow theory?
    Jan
     
  3. jdoclogan

    jdoclogan Platinum Level Sponsor

    I did notice the "squish" was gone. I also have a set of domed pistons. Would they have been used in this old school setup? This being a racing Alpine component I would think it was typically operating at 5000 rpm give or take a 1500 rpm.

    Jan, when comparing the first two heads. Is the sloping metal removal (2nd photo) more to the Vizard design or is my approach (1st photo) with a more vertical metal removal?
     
  4. spmdr

    spmdr Donation Time

    Tough to see details in the pics...

    Go for BIGGER pics (he suggests with BIG Cheekie grin).
     
  5. Shannon Boal

    Shannon Boal Bronze Level Sponsor

    Sure seems like a lot of metal removal (is there some risk here?)....maybe the last head was for a turbocharged engine? The ideal chamber would be a sphere, so maybe a deep dish piston could work well with that last head at 15-20 PSI boost. We need a new production of cylinder heads!
     
  6. spmdr

    spmdr Donation Time

    The recent head guy I talked to asked if I had a head he could cut up.

    I'm looking for anyone who has a cut up Alpine head.

    OR good Pictures of said cut head...

    DW
     
  7. alpine_64

    alpine_64 Donation Time

    Dan,

    Contact the recent posters in the wanted section who were looking for a head as theirs were junked.. Their junk ones would be ideal for you
     
  8. jdoclogan

    jdoclogan Platinum Level Sponsor

    DW
    I have a couple dozen heads. Which plane was your machinist thinking of cutting.

    upload_2021-7-27_13-3-53.png
     
  9. spmdr

    spmdr Donation Time

    I have a stack of Alpine heads as well. I could sacrifice a head.

    BUT, there are several casting numbers and I wouldn't expect them to all be the same inside.

    I just assume there have been a few that have "Been there, done that" with the Alpine heads.

    So I'm looking for those few people, if they are still around.
     
    Last edited: Jul 27, 2021
  10. Alpine 1789

    Alpine 1789 SAOCA President Platinum Level Sponsor

    Not to go off topic, but that is quite the collection. I may show this photo to my wife the next time she kids me about my parts stash!
     
  11. alpine_64

    alpine_64 Donation Time

    Dan... I assume your head guy is more interested in the path and profile of the intake and exhaust runners in the head and the interface with the valve opening to chamber...
    Apart from the holbay head which had a tappered intake all the other rootes alloy heads had the same port design.. Only change was the slight enlargement of the valves around 61 and miniscule change in chamber shape ( as documented in the vizard book.

    The rootes archive will have the detail sections of the head in their drawings.. I have a copy oh the holbay head drawing with the tappering intake runners.. Various cross sections and long section and chamber shape
     
  12. jdoclogan

    jdoclogan Platinum Level Sponsor

    I will start another thread in General Chit Chat "How is your parts stash doing?"
     
    Last edited: Jul 29, 2021
    Alpine 1789 likes this.
  13. Thor 1211

    Thor 1211 Silver Level Sponsor

    I don't want to hijack your new "Parts Stash" thread but some time ago I came across this quote which has been attributed to you:

    "The Promotional Harrington Le Mans (PHLM) has twin 38 Italian DCOE Webers (NOS when installed), The starter jets are 90F9. However, I don't use a choke and find starting to be an owner specific technique for each car. With the PHLM I let the electric fuel pump run for a few seconds - give the accelerator pedal a couple pumps - turn over and it usually fires-up and stops - repeat until it fires again and feather the pedal for a few seconds until it warms-up. Run the engine up to 2000-2500 rpms and let off to an idle of about 800-1000rpm.

    I did google search "Starter jet on DOCE weber" and found this September, 2014 response from a query as to "what the starter jet does:"

    I came across a pair of 38 DCOE's, bought them and was digging around for some set up info for my series V. I suggested to some other tuners that the 38's were appropriate and was promptly told that they never came on any Alpine including the PHLM. Can you do me a favor and confirm that they did?
    I have done the Vizard mod to the head and will probably run with the stock cam. Can/will you give me any advice about a baseline for jetting?
    thanks and regards.
     
  14. RootesRacer

    RootesRacer Platinum Level Sponsor

    The choke size is everything when it comes to main jetting.
    With the idle jets, the cam and compression is everything. with your 38DCOs, the progression holes will probably
    be different than those on newer carbs, so the idle jets will have to be tuned out based on how things work on your engine.
    Most alpines run F9 or F16 emulsions, most 4 cyl engines below 2 liters as well.
     
  15. Thor 1211

    Thor 1211 Silver Level Sponsor

    Thanks for that. I suspect that the progression holes on mine are application specific not generic like later 40s so I'm preparing for a little trial and error after installation.
     
  16. jdoclogan

    jdoclogan Platinum Level Sponsor

    My PHLM came with duel downdraft Zenith 150s. 40 DCOEs were an option available in 1962. My 38s were NOS with manifold when I bought them in 2008. I installed a KB Delta Cam. Engine has 30 over pistons otherwise it is stock 1725 (original, which I have, is 1592). Photo shows setup. Circled numbers are diagram references.
     

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