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Hot Rods Runnin rich!

Discussion in 'The Hokey Ass Message Board' started by Boden, Jun 17, 2020.

  1. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    So as some of you may know I have a 255 merc flathead bores out with heads,cam,port job, and a 2 deuce offy intake with dual 94s. They have .049 jets in it and stock powervalves. My air filters paper has been ripped out and just the fine bug next and larger bug net is left. What could this be. Everyone I talk to says they run .049-.051 jets in their carbs and it works fine. For me it’s so rich my boss said it was burning his eyes. And another thing is my plugs are fouled. And they are autolite 216 plugs. But the end of the ground strap is flush with the end of the threads. My boss is telling me this is wrong. And the electrode should protrude Into the combustion chamber to make a efficient burn. What am I doing wrong?


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  2. Mart
    Joined: Mar 3, 2001
    Posts: 4,103

    Mart
    Member

    Check some of these things.

    Ruptured float.
    Needle valve not seating.
    Float level too high.
    Wrong type power valves, and/or incorrect gaskets.
    Damaged diaphragms in power valves.
    Distortion in lower body and throttle body causing vac leak into power valve chamber.

    All the above will cause an over rich situation.

    Don't worry about the plugs for now, you can't stick the electrode down too far or the valve will hit it. They won't cause it to be rich. being rich will cause the fouling if extreme.

    I may have missed something out but those things are where I would be looking first.

    Mart.
     
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  3. jimmy six
    Joined: Mar 21, 2006
    Posts: 6,402

    jimmy six
    Member

    Fuel pressure to high
     
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  4. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    Ooo. That’s a good one. Didn’t think of that


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  5. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    Float is ok. Checked the float height and re adjusted it, needle is seating 100% all new gaskets. All the gasket surfaces sanded flat. It has stock power valves in each carb. So thag might be the problem


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  6. sdluck
    Joined: Sep 19, 2006
    Posts: 2,430

    sdluck
    Member

    What dist is in it,original one?
     
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  7. lippy
    Joined: Sep 27, 2006
    Posts: 4,607

    lippy
    Member
    from Ks

    Jetted too big.? Cant be though your buddy's are fine. Lippy
     
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  8. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    Mallory dual point. Flat cap


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  9. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    That’s what I thought, and what most people are saying. That’s why I’m so confused


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  10. Mart
    Joined: Mar 3, 2001
    Posts: 4,103

    Mart
    Member

    You're not jetted too big. It will run fine on 51s let alone 49s.

    It's too rich because of one of the things listed (I did leave out fuel pressure).

    What sort of fuel pump do you have? Do you have a fuel pressure gauge? You want no more than 2.5psi.

    Mart.
     
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  11. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    Truck64
    Member
    from Ioway

    One thing I haven't seen mentioned, where did the jets come from? Just because they are marked .049 doesn't mean anything. They should be checked with a # drill set because it is very common to find drilled jets.
     
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  12. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    Very very good point. I will have to check this


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  13. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    I am running a electric pump. And a offy tegulator. I forget what I have it set at. I will check when I get home


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  14. jockeyshift41
    Joined: Mar 23, 2020
    Posts: 37

    jockeyshift41
    Member
    from Florida

    Power valves too big. I run 4.5’s in my dual 94’s on a 239 8BA. I think stock is 7.5. Make sure you have the correct ones that doesn’t have a radius at base of threads or it won’t seal good allowing fuel to leak past.


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  15. missysdad1
    Joined: Dec 9, 2008
    Posts: 2,934

    missysdad1
    ALLIANCE MEMBER

    Be sure to check your fuel pressure with a reliable gauge. The Offy-style pressure regulators are known to be unreliable and the numbers on them are not necessarily accurate. Using a fuel pressure gauge as your reference set your fuel pressure around 2 lbs. This should end your problems unless the regulator is faulty, in which case you'll need to replace it. You might need more fuel pressure if you ever go racing but this should be okay for general driving. Good luck!
     
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  16. F-ONE
    Joined: Mar 27, 2008
    Posts: 2,123

    F-ONE
    Member
    from Alabama

    The old speed manuals and I do believe Fix Your Ford (1958) recommends plugging 2 of the ports on the economizer valve in a 94 set up for duals.
     
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  17. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    The power valve?


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  18. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    [​IMG][​IMG] what type of power valve is this. It came in the rebuilt kit. And it looks like it works backwards. Could this be used as a plug?


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  19. Mart
    Joined: Mar 3, 2001
    Posts: 4,103

    Mart
    Member

    Not sure of the name but it isn't a power valve. On certain models it is on the front of the carb (or is it the back?) and is to do with the signal for the loadamatic vacuum advance. (Spark valve? something like that?)
    It is not intended to be used as a plug.
    What is your vacuum at a gentle acceleration? You need to know what it is so you can work out if your power valves are ok or not.
    I have a dual vacuum/fuel pressure gauge that is really useful to diagnose these issues. If you don't have one, maybe you could see if you can get one.

    Mart.
     
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  20. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,469

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    Plugging power valves are a bad idea.
    That was an Old way of bypassing a problem that can be remedied by finding the correct size for both carbs.
    They are designed to kick in during acceleration for progressive controlled power and economy. A good thing.
    I’ve run power valves for my two 94’s for decades. I have great power and get 16mpg.
    The best on this subject ever.

    https://www.jalopyjournal.com/forum/threads/motor-why-stromberg-97s-over-94s.4618/
     
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  21. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    Oh ok. I have some 4.5 layin around. Maybe I’ll put them in


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  22. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    What power valves do you run


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  23. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,469

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    Sorry don’t remember.
    I’d have to guess. 4.5 maybe????????
     
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  24. jockeyshift41
    Joined: Mar 23, 2020
    Posts: 37

    jockeyshift41
    Member
    from Florida

    [​IMG][​IMG][​IMG]the spark valve screws into the cast iron base on later model carbs. The correct economizer or “power” valve is pictured on the right with no radius at base of thread. Also beware of some valves that have larger plungers that can hang up on the side against carb body.


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  25. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    Truck64
    Member
    from Ioway

    Jetting, & powervalves, and general carburetor calibration are widely misunderstood. Now I'm not gonna argue I'm a carb guru, but a few hours spent going through the shop manual, and theory of operation and the setup and adjustment in the carburetor manuals will go a long ways.

    Most of the adjustments people talk about are bench settings that just baseline everything, so the engine will run after installation. They are the simply a starting point, by no means the final adjustment.

    The spark plug condition will tell the tale. With modern gasoline, they should be very, very clean burning if ignition and carb calibration is optomized.
     
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  26. Boden
    Joined: Oct 10, 2018
    Posts: 712

    Boden

    Black! Dark dark black. My boss is a machinist. And he said the exhaust was burning his eyes it’s so rich


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  27. carbking
    Joined: Dec 20, 2008
    Posts: 2,797

    carbking
    Member

    Lots of really good information in this thread, but 93 percent of all carburetor issues are ignition. Any tests on the ignition system?

    Jon.
     
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  28. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 998

    19Eddy30
    Member
    from VA

    Modern gas formula off pump will lie to you, plugs always look rich, look at new cars they're controlled by computer tail pipes are black, buy yourself a good wide ban O2 gauge it will lead you in the right direction once that's established remove gauge,
    My Flatty With twin carbs has 4.5 pv & 48 jets
    Pressure 2psi, initial timing 13 deg
     
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  29. flatheadpete
    Joined: Oct 29, 2003
    Posts: 9,712

    flatheadpete
    Member
    from Burton, MI

    I ran 51's and 4.5 PVs on 94's on my 1951 286 Merc flatty. Now granted...every set up needs fine tuning but mine ran great. Also ran an electric pump with a Holley regulator set at just over 2psi and a pertronix on a stock '51 dizzy with good wires and Autolites.
     
  30. jimmy six
    Joined: Mar 21, 2006
    Posts: 6,402

    jimmy six
    Member

     

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