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Technical Thickstun question

Discussion in 'The Hokey Ass Message Board' started by alanp561, Nov 7, 2018.

  1. alanp561
    Joined: Oct 1, 2017
    Posts: 648

    alanp561
    ALLIANCE MEMBER

    Back in early March of this year, I was helping a friend go through a semi-trailer full of flathead stuff that hadn't been opened up since 1991. In the mix of stuff I brought home, there were two Thickstun manifolds, one PM-7 high rise and one much lower and with different runners. The short one is definitely a Thickstun as the name is cast into it. I'm sure it's not a cut down PM-7 as nothing that would identify it has been ground off. After trying to research it, I can't find any information on it at all. I know that Thickstun made some one off's and some short production runs. In the pics you can see the differences in not only the runners but the generator mount. PM-7 is in the background in second picture. Does anyone have an idea what this manifold is? DSCN2931 (1).JPG DSCN2933 (1).JPG
     
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  2. V8RPU
    Joined: Sep 23, 2010
    Posts: 200

    V8RPU
    Member
    from Nor Cal

    Pre war Thickstun, one of the first 2 carb. after market hot rod intakes. I've seen them in various heights, not sure if they came that way or have been shortened
     
  3. alanp561
    Joined: Oct 1, 2017
    Posts: 648

    alanp561
    ALLIANCE MEMBER

    I don't believe the one has been shortened. Everything about it is different from the tall one. Biggest differences seems to be the height of the area between the throats and the vacuum port locations
     
  4. alchemy
    Joined: Sep 27, 2002
    Posts: 13,991

    alchemy
    Member

    As he said, it is a different design made pre-war. I have one of each, but both of mine are full height. I think your pre-war has been cut down after production for some reason.
     
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  5. 302GMC
    Joined: Dec 15, 2005
    Posts: 5,548

    302GMC
    Member
    from Idaho

    I have a red "dogbone" Chev 216 intake clearly made by Thickstun - not so marked, has not been altered.
     
    Last edited: Nov 8, 2018
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  6. alanp561
    Joined: Oct 1, 2017
    Posts: 648

    alanp561
    ALLIANCE MEMBER

    Thanks to everyone who has weighed in on this. While researching this, I came across a
    Hot Rod Magazine
    article from October 2012 where there were dyno tests done on several flathead manifolds, multi carbs and 4 bbls. While reading the article, I found that the PM-7 gave away 13 hp to a tall Offy, 11.6 hp to a tall Edelbrock and 8.4 hp to a Navarro. If people were cutting them down, maybe the Thickstun wasn't as good as thought. I know when Thickstun was working with Edelbrock, there was a disagreement about the manifold design and Edelbrock made their own.
     
  7. alchemy
    Joined: Sep 27, 2002
    Posts: 13,991

    alchemy
    Member

    I think the reason the Thickstun PM-7 didn't flow well was the hard edge right at the bottom of the highrise runner. Cutting the highrise down a bit doesn't remove that hard 90 degree edge.

    Just a little trivia, the PM-7 era Thickstun parts were painted red from the factory. And, I think the early stuff might have been painted green, but can't confirm this.
     
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  8. quickchangeV8
    Joined: Dec 7, 2010
    Posts: 323

    quickchangeV8
    Member

    Alchemy is right about that 90 degree angle on the Thickstun PM-7. You can put your finger in the base of the intake and you can feel that hard angle. I have several Thickstun intakes. I have one of the lower pre war ones and to me the one I have looks like it was cast that way. I remember Bruce Dahl telling me that the lower Thicktun PM-7's were also cast that way and were not cut down as many people seem to think. The guys on the dry lakes were beginning to discover aerodynamics and were installing aluminum track noses and running full hoods to take advantage of the wind stream effect. A 1927 roadster with a full hood and a track nose was light weight and consequently was very fast and hard to beat. Tommy Thickstun cast his low style PM-7 intakes so they would fit under the hood of the lakes roadsters. At the swap meets I go to there is usually a few Thickstun PM-7's around and you can still see a few spots of red paint left in some of the corners of these intakes.
     
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  9. alanp561
    Joined: Oct 1, 2017
    Posts: 648

    alanp561
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    Thanks for that information.I am pretty sure the manifold I have hasn't been modified from it's original casting. Do you think that 90% angle would cause the loss of so much horsepower?

    Sent from my SAMSUNG-SM-G891A using The H.A.M.B. mobile app
     
  10. Atwater Mike
    Joined: May 31, 2002
    Posts: 9,623

    Atwater Mike
    ALLIANCE MEMBER

    I know that the info on 'giving up 13 H.P. to Edelbrock' has to be accurate, because recent dyno comparisons have shown Edelbrock's classic intake to outrate others by that same figure.
    "Go figure..."
     
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  11. alanp561
    Joined: Oct 1, 2017
    Posts: 648

    alanp561
    ALLIANCE MEMBER

    The HRM article was pretty interesting. The 4 bbl. manifolds didn't do as well as the multiple carbs. All the tech data is in the article.
     
  12. ol-nobull
    Joined: Oct 16, 2013
    Posts: 1,203

    ol-nobull
    Member

    Hi. On the Thickstun items there is an ebay seller listing a bunch of new items stating made from original patterns. I do not know if he is kin or just purchased the original patterns - molds. About 2 years ago I purchased one of the Chevy finned rocker covers for my inline 6 engine & it is great. Here is a link to his current listing for that item and once there you can click on see sellers other items. He has both of the flathead intakes pictured above in NEW as well as some other stuff including model A intakes. Jimmie
    https://www.ebay.com/sch/eastcheam8...RbJuhK:rk:1:pf:0&rt=nc&_trksid=p2047675.l2562
     
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  13. alchemy
    Joined: Sep 27, 2002
    Posts: 13,991

    alchemy
    Member

    ol-no, a majority of the parts that fella has for sale on Ebay are new creations, not castings that were available back in the day. Thickstun didn't make those fuel blocks, air cleaners, carb adapters that he is selling. The PM-7 looks rather accurate though.
     
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  14. 2muchstuff
    Joined: Mar 17, 2004
    Posts: 295

    2muchstuff
    Member
    from Eastern KS

    I'm fortunate to have a NOS PM-7 in it's original red. It's so nice I'll probably never run it.

    Intakes.jpg
     
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  15. cs39ford
    Joined: May 1, 2012
    Posts: 748

    cs39ford
    Member

    Yes you are right. Bruce told me they made both. And he had both in his collection
     
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  16. alanp561
    Joined: Oct 1, 2017
    Posts: 648

    alanp561
    ALLIANCE MEMBER

    It is nice but I believe that rather than have it hanging on a wall or sitting on a shelf and impressing the occasional visitor with your "NOS PM-7 in it's original red", I'd have it on a running car that I'd drive as often as I could and tell anyone that's interested the story of how I came to have a "NOS PM-7 in it's original red". Just my opinion.
     
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  17. quickchangeV8
    Joined: Dec 7, 2010
    Posts: 323

    quickchangeV8
    Member

    2muchstuff, thanks for taking the time and posting the pictures of your NOS Thickstun PM-7. I have never seen or even heard of one of these intakes in original NOS condition and I have been around flathead speed stuff for a long time. You certainly have a jewel there, and I really enjoyed seeing it.
     
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  18. alchemy
    Joined: Sep 27, 2002
    Posts: 13,991

    alchemy
    Member

    I usta have a PM-7 with original red paint on it, but let it go in a short-cash moment. It went to an Illinois HAMBer about a decade ago. It was no where near NOS though.
     
    alanp561 likes this.

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