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Hot Rods Tunnel Ram Start

Discussion in 'The Hokey Ass Message Board' started by udnudn, Dec 10, 2017.

  1. udnudn
    Joined: Aug 10, 2017
    Posts: 10

    udnudn

    Will be putting a tunnel ram setup on my 30 coupe this Winter. Using an Edelbrock TR1Y manifold and two Holley 600 with vacuum secondaries. Carbs are rebuilt with the following in them..Front jets 66, Power Valves 6.5, Squirter nozzles .025, vacuum pods connected together with hose. Will be going on a 355 big cam and roller rockers. Don't know much else on motor. It currently has 3 deuces on it and runs good. Turbo 350 transmission. Ford 9" but don't know ratio. Runs about 2900 rpm at 70 mph. The rear tires are P285/70R15.

    What I am looking for is if there are any obvious changes I should make to carbs before I mount them up. Just trying to save a little frustration at start. And yes I wanna do this!;0)

    Thanks for any help!!
     
  2. Morrisman
    Joined: Dec 9, 2003
    Posts: 1,600

    Morrisman
    Member
    from England

    C495A6E7-7E2C-4290-A63F-B9F2529C1B09.jpeg

    I put a Weiand tunnel ram and twin 600 Holleys on my RPU. No advice to give really as I never ran it to the max at all, or set it up too well to run max power, roads were too screwed up where I lived.

    Couple of car guys, engine builders, I knew were a little surprised I had it idling so smoothly at 700rpm.

    It sure looked the part and ran well enough when I stood on it a bit occasionally.
     
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  3. saltflats
    Joined: Aug 14, 2007
    Posts: 9,558

    saltflats
    Member
    from Missouri

    I would check the list #on the carburetors and install jets and power valve and rear jets or metering plate to factory specs and start from there.
    If you have to make big changes to get hem close maybe there is something else wrong or they are just not correct for you combination.
    If you list the #s I may have the specs.
     
  4. pitman
    Joined: May 14, 2006
    Posts: 4,705

    pitman
    Member
    from Hampsha

    fitzios '29.jpeg
    1972, Windsor, Ontario. George Fitzios' 427 side-oiler. Used gear driven secondaries, car was tuned to accel! Felt like a Saturn five launch.
     
    Last edited: Dec 11, 2017
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  5. You are going to have to get it running and see if it is rich, lean etc. Plan on tuning and more tuning to get them right. You will have to tune for idle , cruise, and full throttle.
     
  6. Mike VV
    Joined: Sep 28, 2010
    Posts: 1,613

    Mike VV
    Member
    from SoCal

    Drive easy to begin with then work up to harder driving, freeway driving. Keep a close look on the (fresh) spark plugs at every step. The jet sizes and power valve you mention...are reasonable for single carburetor and small plenum. You have a much larger plenum now..!
    The squirter nozzles should be at least .031"'s to start. They'll need to fill a huge flat spot you'll have. The cam and cam rotation will need to be experimented with also. Think...more fuel.
    Actually...if there is a dyno shop near you...THAT's the best bet to get all the tuning done so the engine is happiest.

    Mike
     
  7. Morrisman
    Joined: Dec 9, 2003
    Posts: 1,600

    Morrisman
    Member
    from England

    I was told to expect zero low end power, no pull below 3000rpm, flat spots etc, but mine revved and took off far better than it ever did with a stock Chevy corvette manifold and a single 600 Edelbrock carb. Instant power as soon as I hit the throttle.

    The Edelbrock would just make it fall flat on its face if you stepped on it hard at low rpm.

    I only fitted the tunnel ram for the ‘bling’ factor, but I was very pleasantly surprised just how well it did run. :cool::D
     
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  8. chevy57dude
    Joined: Dec 10, 2007
    Posts: 5,038

    chevy57dude
    Member

    Saltflats' advice is sound. If possible, run each carb on a single 4 barrel engine 1st. Tune with a vacuum gauge individually, to get them closely matched. Of course, there are variables introduced with this method. But a good way to spot an issue with a particular carb, prior to running them as a pair. The ''poor man's flow bench''. Best wishes with it.
     
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  9. udnudn
    Joined: Aug 10, 2017
    Posts: 10

    udnudn

    Thanks for the tips guys. Looks like I will see how they run when I finally get them on. I might change the squirters before hand since I have .025 in them now. Move on up to a .031. The carb number is and 1850.
    Will be back when running, but may not be till beginning of new year!
     
  10. I built a tunnel ram manifold in about 1968 for my 331 hemi. Designed it in physics class in JC, Ran a Rochester 4-Jet carb. Zero bottom end for sure. The theory is they free up the system to one degree of freedom for the organ pipe pressure pulses that supercharge the cylinders at one designed engine RPM. They hurt performance at other speeds. The shorter the runner the higher the boost RPM. This design eliminates the spurious pressure pulses in a conventional manifold that result from flow through the carb, from other pulses coming from adjacent runners, etc., at the expense of good air velocity. In practice they look great but are pretty poor technology.

    Old days 2.jpg
     
  11. This is leaving at 2,000 rpm with a small block, don't believe the no low end hype Badmoondeadon.jpg
     
  12. That is exactly what tunnel rams are for!
     
  13. Morrisman
    Joined: Dec 9, 2003
    Posts: 1,600

    Morrisman
    Member
    from England

    Yes, mine would take off like a scalded cat from crawling along at idle, to spinning rubber and howling tires, just by stamping on the throttle. The rumours about no power below 3k are just rumours.
     
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  14. Deuces
    Joined: Nov 3, 2009
    Posts: 17,792

    Deuces
    Member
    from Michigan

    Just gotta know how to "fine tune" the setup on your motor...;) 44c09e906a72d72aa141987dd3ab2d83--christmas-humor-christmas-stuff.jpg
     
    mad mikey likes this.
  15. Years back I had a 355 cid sbc in my coupe . Lots of cam and a 3500 stall. Two 500 eddys on a tunnel ram. After some extensive tuning this set up worked great. In town, very respectable manners, on the highway or at the track, she was a beast. ;)
     
  16. models916
    Joined: Apr 19, 2012
    Posts: 380

    models916
    Member

  17. oj
    Joined: Jul 27, 2008
    Posts: 6,155

    oj
    Member

    Go with 4.5 power valve, the 6.5 won't be fully closed and the engine will be 'false rich'; go with .028 squirters. You'll probably have to mess with the secondary vacuum springs, esp with a light car & cam. I'd invest in one of those kits for tuning the vacuum pots by removing just the top cover, the regular vacuum secondary pot has to be removed from the carb to take the top off, the kit provides a new top that you can access the spring without removing the pot. I suspect you'll need a light spring to open the secondaries.
     
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  18. Deuces
    Joined: Nov 3, 2009
    Posts: 17,792

    Deuces
    Member
    from Michigan

    Got two of those on my tunnel ram setup with the vacuum line... One of Ford's better idea's.... :)
     
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  19. Kan Kustom
    Joined: Jul 20, 2009
    Posts: 2,316

    Kan Kustom
    Member

    Thanks to all contributors here. Lots of information and experience.
     
  20. Tickety Boo
    Joined: Feb 2, 2015
    Posts: 1,002

    Tickety Boo
    Member
    from Wisconsin

    Holley quick change spring kit # 20-73 is made for 2 x 4 Holley vacuum secondary carbs, it allows you the option to add a vacuum line to join both pods to equalize vacuum , insuring both carbs open secondaries equally when running same spring.:cool:

    With the big cam not making much vacuum at idle, lower the power valve number to about 1/2 of what your vacuum gauge reads at idle. example: 9 lbs vacuum = 4.5 pv

    Norb
     
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  21. Morrisman
    Joined: Dec 9, 2003
    Posts: 1,600

    Morrisman
    Member
    from England

    Friend of mine had to do that, his secondaries were opening unevenly. Not sure if it makes any real big difference to performance, but for racing you want all the extra you can get.

    He had me hunkered down in the passenger seat watching them open as he ran down the 1/4 mile..... o_O
     
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  22. udnudn
    Joined: Aug 10, 2017
    Posts: 10

    udnudn

    Thanks for all the tips so far. Probably won't get on car for a few more weeks. Loots of good info, especially kit to put lighter springs in vacuum


    Hey Norb

    One quicky. When I get to checking vacuum, where do I check it at? From each carb at the base, or do I check at vacuum hole near top of the manifold?

    Thanks!
     
  23. saltflats
    Joined: Aug 14, 2007
    Posts: 9,558

    saltflats
    Member
    from Missouri

    You want to check manifold vacuum so that would be any port under the throttle plate.
     
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  24. Tickety Boo
    Joined: Feb 2, 2015
    Posts: 1,002

    Tickety Boo
    Member
    from Wisconsin

    Hey Norb

    One quicky. When I get to checking vacuum, where do I check it at? From each carb at the base, or do I check at vacuum hole near top of the manifold?

    Thanks![/QUOTE]
    Yup, like Salty Said

    Ether carburetor at the base, or the vacuum hole near the top, should all read near the same vacuum for your test.

    What ever one is easiest to get to.

    If it is together, :rolleyes: you might want bring it up to operating temp and do a baseline test
    to tell you what vacuum you cam is making now.;)

    Norb
     
  25. tuning, tuning, tuning and understanding what the engine is doing to make changes.
    Long runners, small plenum, short runners large plenum? Long runners, large plenum use very small carburetors.
    This is for STREET driving....The reason people say they do not have any low end is because of a mis-matched combo....too big carb, short runners, large plenum and or the wrong power valve.
    ^ 2X, use a 4.5, 3.5 power valve to start , especially if you are using a "racing" cam.
    Bogging or hesitating?
     

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