Safer carburettor in a box?

Discussion in 'Inboards' started by tom kane, May 22, 2014.

  1. powerabout
    Joined: Nov 2007
    Posts: 2,916
    Likes: 63, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    Ike
    how could you possibly support the plastic filter over the engine when the same size filter is in the fuel pump and that is hard plumbed to the carb?
    my guess totally illegal under uscg rules?
     
  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 482, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    These plugs are easily popped out and replaced and often included with comprehensive rebuild kits. Usually, you can pound them sideways in their bore and grab with a pair of pliers, like a freeze plug, but sometimes, they're full of pin holes and rust and have to be drilled. I wouldn't trust room temperature cure epoxies with an engine in a box, where temperatures can reach over 150 degrees.
     
  3. gonzo
    Joined: Aug 2002
    Posts: 15,249
    Likes: 951, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I mean install the new plug with epoxy.
     
  4. Ike
    Joined: Apr 2006
    Posts: 2,496
    Likes: 353, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    Powerabout, if you noticed I said, the filter is gone. You are right. You should never use one of those plastic auto in-line filters. They do not meet the 2 1/2 minute fire test and they have a bad habit of falling off. I have investigated boat fires where that was the source of the fuel for the fire.

    Everything now meets USCG and ABYC standards.

    When I bought this boat it had been sitting in someone's yard for about ten years. The owner had bought it and then let it sit and never did anything with it. The owner previous to that had done some really stupid stuff. It had automotive parts all over it. Those are all gone and replaced with marine parts.
     
  5. whitepointer23

    whitepointer23 Previous Member

    interesting tom. i enjoy reading about your different experiments.
     
  6. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    If you want to avoid Demenia whitepointer plus a few other ageing problems just keep your mind active.

    All of my experiments are now out-dated because I now have a new approach to making my family boat safer in design..but I doubt if othe people may agree because it`s different.

    Some old outboards had the carburetor on the tiller handle which was a tube about 18 inches long. Handy to the choke and throttle and ofcourse the added advantage of the ram effect, probably much easier to start too.
     
    Last edited: May 27, 2014
  7. sdowney717
    Joined: Nov 2010
    Posts: 1,001
    Likes: 55, Points: 48, Legacy Rep: 274
    Location: Newport News VA

    sdowney717 Senior Member

    On the quadrajet, I tap the plug on top for a 1/4 inch pipe thread plug, if you mean the plug that fits over the adjuster for the fuel needles stop height can be adjusted up and down.
    The accelerator pump shaft has a internal seal held in by a washer on the underside of the airhorn, or it should.

    Quadrajets do not have rubber seal rings on throttle shafts and neither did my old 4GC 4 bore. The 4GC did put a tapped in plug on one side of the throttle plate for the shaft. I read that they stopped using orings on shafts long ago due to they swell up and bind the shafts. Gas that overflows down the bore will leak past the throttle plates.

    Not all marine quadrajets have jtubes, some have a vent collar. On a forum somewhere I read for land use on some kind of racer RV, dune buggy, etc... people removed the jtubes as they claimed it affected the fuel mixture due to extreme vehicle movements.

    My quads do have the curved vent tubes. If you look at the interior of airhorn on a quad, there is a long large central slot right in the center that is also a bowl vent, so overflow is going to come out there I think preferentially vs the jtube.

    If your quad has worn throttle shafts it is most likely the holes in the aluminum base plate are worn, not the shafts. I have bushed these with brass tubing from a hobby shop. You drill out the throttle shaft hole and press in the brass tube. Turns out the tube is a perfect fit for the shaft size. I have fixed 4 quads doing this.

    Warped airhorn is easy to fix. You have to heat the airhorn to about 350 degrees using a propane torch with it bolted down and use a screw clamp in the problem area. Pot metal under low heat relaxes and it will move. there is some skill involved here, too much heat the casting will melt. Mostly the problem area is the large front bolts people overtorque and that is easy to fix.

    I have rebuilt at least 50 carbs over decades and the marine ones are identical except for bowl venting. And on some the fuel hose fitting for a mechanical fuel pump when the pump diaphragm fails. The early quads have an extra drilled passage with a pressed in tube for the hose on the front of the carb where the fuel dumps into the primary venturi. Auto carbs will have numerous useless vacuum ports, fuel returns fro the charcoal canister, that are not needed on a marine carb.
     
  8. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    The carb in a box was for me a successful very cheap experiment to make my boat safer for me and my family,no massive development cost.Of course it can and has been improved. For me it is past history and I would only have my own design Remote Fuel System for power boats in my boats and bugger government old fashioned out of date Regulations and control freeks.
    You can build what you want of your own safer systems and you can comply with local boating Regulations.
     
  9. powerabout
    Joined: Nov 2007
    Posts: 2,916
    Likes: 63, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    I still think you designed a box to explode...
    I would have altered the carb so it couldnt leak externally as per any other marine carb
    I shudder to think if the carb leaked then there was a backfire....
     
  10. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    Any wet fuel in the box is scavenged into the induction manifold as is any gas forming. Use backfire screens as any marine carb would and backfire can not enter the carb in the box because it can not connected directly, and the scavenge tube has a one way valve.
    The idea is for you to come up with an improved design.Try it. Whatever you come up with must be better than what has often been used.

    Just another interesting thing about some induction manifolds fitted to boats and autos, some had air bleed valves or just small slots at a low part of the manifold where unburned excess fuel could leak away during choke starting but many people did not even know they were there. Other motors such as Jaguar had air bleeds with tubes to drain the excess fuel away and you could see a stream of fuel running out of thes tubes that would be great in a boat. If you block these bleed ports you alter the fuel settings.
     
  11. powerabout
    Joined: Nov 2007
    Posts: 2,916
    Likes: 63, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    Hi Tom

    Surely if you connect your box to the inlet manifold you have a constant vacuum leak?
    For the fuel/vapor to get out of that box where do you let the air bleed in?

    cheers
     
    1 person likes this.
  12. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    A gasket between inlet manifold and carb and carb box seals the joints, box just becomes a seperate container to catch gas and wet fuel which may or may not occure. Air fuel goes through the venturi not into the box.
     
  13. powerabout
    Joined: Nov 2007
    Posts: 2,916
    Likes: 63, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    ok
    then how does the box drain or is it effectively part of inlet manifold so sealed right to the top of the carb, which I guess puts low pressure around the carb which cant really do anything assuming all bowl vents still open to the air but yes would catch any leak thats for sure?
     

  14. tom kane
    Joined: Nov 2003
    Posts: 1,767
    Likes: 48, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    The box in not under low vaccum but a pickup tube to drain the box is. This vents and removes any excess fuel.
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.