I give up! - advice on who can help - oil everywhere post rebuild

Discussion in 'Mech Tech' started by Dave Goddard, Apr 25, 2021.

  1. Zed

    Zed Gradually getting grumpier

    ...unless he compensted for the wrong float height, but then you wouldn't want to cling to his jetting anyway.
     
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  2. mikedjames

    mikedjames Supporter

    Basically the 1641 is a bit "small" for large carburettors. Its not moving enough air. [It doesnt even move enough air to make a progressive work well, as its about half the engine capacity of a Ford Granada 2.8 which is one car it was intended for]
    And so the tuning of those carburettors will be on a knife edge. Not enough air flow to get a decent vacuum for sucking up fuel or ignition timing advance. So it will wobble from ultra-rich to ultra-lean as the fuel level moves a little.

    But as you spent a lot of money on them , it isnt fair. But its true.

    Fit smaller venturis, the vacuum builds up more, the tuning gets more consistent, you arent looking for airflow up to 9000RPM so you can afford a bit more restriction.

    Dodgy aftermarket stuff ... Like this morning I was flooring it in third going uphill onto the motorway, doing about 45mph, glanced down at the AFR and thinking hmm? 16:1. Changed to 4th gear and it dropped back to 13:1 which is what I wanted (I think it tripped the 5th jet on the progressive carburettor , the "power valve" when I went into 4th. )


    As for gaskets -buy some gasket paper of the correct thickness, a pair of leather working hole punches (the type that does different sized holes) and a ball peen hammer. And you will soon learn how to hammer the outline of the casting so it cuts the gasket to fit perfectly. Then punch the holes for the airways and screw holes with the hole punch. This means that a gasket costs about 50p in gasket paper as you can get several out of a sheet.
     
    Last edited: Jul 10, 2021
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  3. Zed

    Zed Gradually getting grumpier

    Lots of people manage to run 40mm carbs on 1600s. Not ideal but easier than a progressive.
     
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  4. …and you end up with an engine that can actually breath properly :thumbsup:

    Choke ‘em down, slap ‘em on.
     
    Zed likes this.
  5. Thanks all. I ordered one service kit which includes a gasket and one needle valve hoping i dont need two as i hope to ar least get one carb apart without screwing the gasket and hopefully one out of two needle valves / diaphragms will be ok. So when it arrives i will take the carbs off and check the floats at least.
    One thing that has been bothering me is that when the fuel pump is off the fuel pressure immediately drops to zero. I thoughts it should maintain pressure if i dont have a fuel leak and the needle is holding the pressure. Would the fact it drops to zero indicate i have a float /needle issue or is this to be expected?
    Also wondered if anyone has thoughts on specfics on what i should do on the carbs if anything after float check if they are off.
     
  6. Zed

    Zed Gradually getting grumpier

    Take out an idle jet, write down the number.
    Same for mains, main airs and emulsions (these are in a stack, so it's one piece to remove)
    The venturis will have a number visible looking down the throat.
    Then tell us and we'll tell you if there's anything obviously wrong with those choices for your engine.
     
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  7. 77 Westy

    77 Westy Supporter

    It depends on the type of fuel pump whether pressure is trapped or not, but usually the pressure will drop as soon as the pump stops.

    If the carbs haven’t been inspected recently now is the time to fully disassemble and clean them. Actually, the time to inspect them was after the first engine seized up, but better late than never.
     
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  8. Thanks all. The fact the carbs were tuned on a rolling road and it was running great guns i hope means my jets and setup is ok. The running rough is i am assuming to do with carburation but i guess isnot gauranteed. As i said it ran great at the tune up place except for a spell when it was thought we had a vapour lock, but it has been drinking fuel and its now running the same rough even when cool so def not vapour lock. I am working on the assumption i have sticking needle or wrong float adjustment or some crap in a carb. I wonder how likely this is...? Anhow hope to get the carbs off wednesday with service kit stuff coming tues. Would it be worth me uploading a vid if pos for you in the know to hear the engine to see if you think its carbs by the way?
     
  9. Zed

    Zed Gradually getting grumpier

    Don't make assumptions - gather evidence. Hence the jetting questions - you need to know.
    Yes to a vid of it spluttering. :thumbsup:
     
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  10. 77 Westy

    77 Westy Supporter

    Stop assuming things mate. Look at the facts.

    First engine seized – cause unknown.
    Second engine broke a piston – cause unknown.
    Third engine is running rough – cause unknown.

    It sounds like the carbs have never been inspected and you don’t know the sizes of the jets, tubes or vents. But they have been fitted to all three engines. IMO it was a waste of time getting them tuned.

    Running rough could be a dodgy spark plug or lead and there might be nothing wrong with the carbs but start from something that you know is right instead of assuming it’s right.
     
  11. Zed

    Zed Gradually getting grumpier

    Harsh but true.
    However in defence I think people wrongly assume that if they take a trip to a rolling road the "expert" will sort it out and they can hence forth forget about the carbs.

    OP - In reality, if you want it "sorted out" at a rolling road you'll find yourself in their car park changing anything that isn't either a main fuel or idle fuel jet yourself or coming back to try something else. The point being that the initial responsibility is yours to provide something sensible to tune as they will fine tune what you give them. If you give them unbalanced turds with the wrong emulsions and venturis for your application they will tune them as best they can.

    Imagine if you will that the float heights are different in each carb. That means the fuel level in the emulsions will differ which means the fuel/air ratio will also differ from one side of the engine to the other. Your man reads the fuel ratio of those two combined and inevitably one side is rich and one side lean. I could go on. :)
     
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  12. I see your point. I guess its a large degree of ignorance on my part in terms of expectations and what a tune up means. I had said to the tuning guy about my knowledge levels and the history on the van and also said about the floats but as you say it seems its not for them to set the floats and get the basics right. I kinda thought in ignorance that a tune meant sorting carbs, whatever was needed along with anything else ignition related. It was running nice before the visit, and the visit was more in my mind to be 'really' sure i'd not missed anything.
     
    Zed likes this.
  13. I refer you back to my post of over a week ago.....
     
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  14. As above, forget the “tune up”. Take your carbs off and strip them. Check jet and venturi sizes fitted and set the float heights. Post the numbers on here. Then you won’t be guessing.

    Just removing the jets unlikely to affect the “tuning”, whatever that is. The fact that the engine’s running doesn’t really mean anything.
     
    Zed likes this.
  15. 20210713_231101.jpg 20210713_231043.jpg I took both carbs off tonight. Float heights were good at 10-11mm with 30mm max travel. The carb on cyl 1,2 side though did have a problem - the needle valve had ridges in it and would not shut off when blowing in the fuel inlet pipe and raising the float. I guess this could explain a lot. I had one needle valve in the service kit so changed it. The vents are 28s. I could not see numbers on the other jets other than the pic enclosed- where do i look?. I took one idle out but again could not see a number on it. Float bowls look clean. Squirter thingy on both works ok too. On the second carb the shut off on the needle was better but not totally convincing so i cleaned the ridges with some 1200 grit wet dry. Seems to seal now. Slight issue with float spindle loose either end as if it could fall out- should i nick the rod to get it to hold?
     
  16. 28 vents should be fine. Strangulation is good on a van.

    Are your carbs Webers or Dells? You’ve many more jets to take out. They should be sticking out the top of the carbs in their holders (on Dells at least). They should have a number on them showing jet size in 1/100th of a mm. Keep dismantling. You’re not there yet.

    The thing in your pic looks like an emulsion tube. <edit> air correction

    Get an exploded view of the carb off the web. That’ll show you where everything lives.
     
    Last edited: Jul 14, 2021
  17. rstucke

    rstucke Sponsor

    that main jet on the end of the emulsion tube should have a number on it (somewhere between 100 & 135)
    if not there is a problem because it may have been a blank that's been drilled and you'll need jet gauges to determine the size.
     
    Zed likes this.
  18. The carbs are webers. I think proper ones.
     
  19. Def no numbers on jets sadly.
     
  20. Zed

    Zed Gradually getting grumpier

    That is not going to make your life easy and it's impossible now to advise.
    @77 Westy might have something to say about F11 emulsions...
    28 vents should be ok.
    Hopefully your needle valve work will have the desired effect but you still won't really know how much fuel/air you're feeding it.

    BTW don't buy a cheap set of ebay jet drills. I did once and the drills were random, sort of 4 of one size and none of the missing 3, them 6 all the same etc. ha-ha, got my money back without complaint.
     

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