Jump to content


  • Posts

  • Joined

  • Last visited

Posts posted by hchris

  1. Re the distributor vac advance, it picks up vacuum  above the throttle plate so unlikely to be the  cause of your problem, not having it working is more of a tuning issue and road running impact.


    Two very important things about manifold vacuum are where your measuring it (as already mentioned) and how steady are the readings. 


    By design your highest vacuum reading will occur when the throttle is closed, therefore initially for troubleshooting purposes, that needs to be at idle, and because you are measuring below the throttle you need  to tap your guage into the manifold, somewhere like a brake booster port. The distributor vacuum line is not the place to do it.


    So at idle on a reasonably good engine I would expect about 20" and steady,  if it's jumping around then you need to follow a well defined sequence of checks to find the problem. If I'm reading you right though, your problem is just a permanently low reading and that would indicate a manifold / carb base or manifold fitting leak; somewhere in the induction system air is getting in where it shouldn't.


    Having said that, I'm curious about your troubles with the starter vac switch, that's an item which would be reading below throttle vacuum, have you got a leak there perhaps  ?

  2. As well you need to consider wear and tear, timing chain stretch, rubber moulding in the crankshaft hub/pulley, distributor springs and flyweights etc,etc.


    Highly likely that the timing marks are not where they were when built, so what you have done is correct. 


    With a vacuum guage you can get timing almost perfect (on a standard engine) but it requires that you connect a vac guage somewhere in the inlet manifold below the throttle (not the distributor vac port). For instance a brake booster port or similar would be ideal. With engine at idle move the distributor around until you get around 20 - 22 inches of vacuum, this will get you in the ballpark, any higher and you'll be pinging. 


    Go for a run and if it pings back off a few degrees, might be worth looking at the timing marks when you get it right, if it's significantly of my money would be on the rubber insert in the crank pulley. 

  3. Hmmm, if it makes you feel any better I've got a box full of those carbs in the same condition (25 Maxwell in my case) 


    Ultimately I used the best upper body and ground out the pot metal venturi, then had a venturi machined up from aluminum round, noting the position of groove and holes correctly. 


    Given that the venturi profile was mostly guess work it actually worked quite well, now with 3D technology I'm thinking it wouldn't be a huge task to replicate 


  4. Highly likely the sender unit has a dirty wiper arm or bad earth. But with your limited description, makes it hard to judge. Or maybe I missed something  ?

  5. 8 hours ago, rocketraider said:

    Guessing that's Chrysler Australia product. Interesting car. Always good to see what cars the rest of the world plays with.


    Slightly off topic, but Chrysler Australia made these as well.


  6. Ok, my first impression of the needle photo is that it's badly worn, there shouldn't be a wear mark on the taper and probably there will be a corresponding mark in the seat; bottom line is that the shutting off of fuel when the bowl fills is severely compromised. So first thing I would do is buy a new one. 


    As to the proper fuel level, you need to find the correct setting (Google search) and bend the float arm to suit, hard to tell from the photo but doesn't look right from here. 


    So once again, why dont you take off that filter and hook up a (clear)  line and funnel and pour in some fuel to see what level the valve shuts off at, that way you can keep messing with it to get it right.

  7. If you have a sinking float, it gets water(fuel)logged and keeps sinking with the weight of fuel such that it can't ever rise far enough to shut the needle valve, and while the pump keeps pumping the carb just floods.


    Brass floats are soldered together in manufacture and are prone to cracking, which then allows fuel to seep inside thus weighting down the float. If for instance someone has been bending the float arm to readjust the float level, it's not unusual to create a stress crack which eventually gives way and the float takes on fuel and you finish up with a "sinker".


    So you need to take out the float and give it a good shake next to your ear, yo can usually hear if there's fuel in it, alternatively as suggested drop it in boiling water and watch for bubbles which will indicate if it has a hole.


    If the float turns out to be good then you have to determine why the bowl level is obviously too high, as I said inthe previous post, it would help if you make up a rig to fill the bowl from an external source with the bowl cover removed and see what's going on. I don't recommend using the fuel pump whilst turning the engine as it's too much of a fire risk, you would need to syphon out fuel that's in the bowl first up, and keep in mind that if your filling point is elevated you'll be able to simulate a degree of pressure on the float.  


    Ideally you should be able to watch the float rise as you pour in fuel and at some point it should shut the needle valve, and your fuel flow will back up in your delivery line; its handy if its clear pvc so you can see the fuel flowing.

    • Thanks 1
  8. You're right,fuel level is way too high, could be a sinker as suggested or needs adjustment. Strange that it's just popped up out of the blue.


    When I'm messing with float levels I've got a rig where I suspend a small funnel and hose about a metre (yard) above the carb and connected to the inlet pipe. With the top off the carb, as I pour fuel in the funnel, it's easy to see what the float/needle/seat are doing and adjust/fix as required.


    The height of the funnel gives me a head of pressure to simulate pump output. 



  9. Smells flooded - I think I would take the top off the carb and see if

       1. the float/needle and seat are ok, or

      2. if there's any rubbish floating around in the float bowl. 


    Letting the fuel level drop to the bottom of the tank has possibly allowed a whole bunch of rubbish to make its way into the fuel delivery system; good chance that it's contaminated everything from tank to carb. 

    • Like 2
  10. Sounds like the sender, little wire coil gets dirty and you get bad resistance. However, shouldn't have to drop the tank as sender unit is usually mounted externally, at worst you may have to drain the tank if the sender is mounted low down. 

    • Like 2
  11. Ok here's my pitch, doing a 34 Chrysler some years back I had a wiring diagram to follow and used an old hot rodders guide.  Went to the local hardware store and bought a couple of reels of cheap plastic/nylon clothes hanging line; with the aid of wiring diagram ran and cut each wire in nylon, labelled them as I went then laid them out on the floor. Zip tied the lot together and ran the loom through the car snipping/ adding where required, once happy with the fit replicated the whole thing with proper cable and fittings and installed, also this gave me the flexibility to add/alter stuff as I went, such as turn indicators etc.


    So whilst doing the job twice it worked out pretty cheap, as I was able to sort my mistakes out before making up the real deal, and have to say enjoyed the project along the way 

    • Like 3
  12. 7 hours ago, DeLovely DeSoto said:

    I am in Australia. I have been trying to contact a previous owner to get some history. No success so far. There are rumours it came out of South Africa?????


    Think you might be right with South Africa, never seen a plate like that down here. Another thought, what about NZ ?

  13. 6 hours ago, Max4Me said:

    Hello, Marbeton,

    Here's some followup information for you. I took the car for about a 15-20 minute drive (83 degree F air temp, 23 C) and then checked the water temperature. I used a digital probe thermometer and an infrared thermometer. They read slightly off from each other but not significantly (just a degree or two Fahrenheit), so I'm giving you the average of the two. At the fill opening with cap off, the temp of the water is 183 degrees F (84 C). On the outside of the upper return fitting on the radiator inside the engine compartment the temp is 171 degrees F (77 C). Interesting that there would be such a difference. I did not check the temp at the fitting at the bottom of the radiator, but will be glad to if this helps. One interesting thing that I never noticed is that the fan blows air forward through the radiator and not back toward the engine. Not sure what to think of that. I may try reversing the fan blade and see what happens. I have Champion W 14 spark plugs which are exact replacements for the AC 78s plugs you have so I don't believe that's an issue. I have a Zenith carburetor on mine. In one of the manuals I have (darn if I can locate the info right now) it lists the carburetors on the 1925 Four as Ball and Ball, Stromberg and Zenith. Though interestingly enough, the owner's manual illustrates and gives adjustment info on a Stewart, even though it does not specifically name it.  Go figure.


    Beautiful car you have. Mine is not nearly as finished so I doubt I can send pix that would be of any help to you. I 'rescued' it from a gentlemen whose grandchildren wanted to chop it into a street rod. It's a popular thing here in Southern California (and maybe else where) because the pollution controls required are based on the VIN/serial number of the car, NOT the engine. Hence people put a heavily modified big block engine in old cars and don't have to meet any smog requirements.


    VIV has much more experience than I so that is a voice to which I would pay heed. Best wishes and good luck with your troubleshooting.



    P.S., in my original post I stated I'd read people in that era put lead additives in their cars to prevent pinging. It is true that I read that at least twice, and having not lived in the 20's, I can't personally swear to this. However, in retrospect, l even with 60-70 octane rating back then, I can't believe an engine with such low compression would have trouble with pinging. But again, I wasn't there.😬


    Yep, definitely need to turn the fan around.


    In reality once your moving, most of the cooling will be from road draught, the fan comes into play at slow speeds and when stationery. 


    Pretty sure that octane ratings aren't in play here, as mentioned compression ratio is well below the threshold and whilst the cracked manifold definitely needs fixing i doubt it would be affecting the radiator temp.


    If the engine was rebuilt is it possible the timing is out ?

  14. Given that you don't have a water pump, cooling will always be marginal on a thermo syphon system. 


    The fact that you've done the radiator would probably suggest that the block might need a good flush out, after all the cooling effectiveness is very much dependent on good circulation, do you know what condition the block is in ?


    A bit of online research will give you various product options for a flush out, you might want to be a bit creative with the flushing by disconnecting the radiator, be a shame to fill it up with crud.


    Also invest in one of the hand held infrared thermometers and move it over various parts of the engine looking for hot spots, the back of the block for instance.


    While your at it you can check the effectiveness of the radiator by noting the temperature difference between the inlet and outlet ports of the radiator, ideally there should be around 25 degrees drop between the two, if that's the case then the radiator is doing it's job. 

  15. The fact that you've got spark at at the plugs would suggest a fuel problem, start spray or not I would be looking down the fuel path; assuming timing hasn't been messed with ?


    Is it possible to take off the air cleaner and tip a bit (I'm talking a couple of spoonfuls) of fresh fuel down the  carb throat and see if it kicks  ?

  16. 3 hours ago, nzcarnerd said:

    You need to find the engine serial number to prove which model it is. 


    Should be easy enough to find - stamped on the left side near the front just below the head surface.

    Or more precisely, just above the generator where the block and head meet.

  17. Doing a complete brake job on a 29U, everything seized up.


    Have a puller for the rear hub, but how does the front hub come off  ? is it just a matter of removal of front bearings and taking the hub off ?


    • Like 1
  • Create New...