Chrystler Crown flathead 6

Discussion in 'Inboards' started by TollyWally, Jun 21, 2009.

  1. TollyWally
    Joined: Mar 2005
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    TollyWally Senior Member

    A buddy of mine has a beautiful old woodie with a Chrystler Crown flathead 6 in it. It's running poorly at the moment. We've been having ethonal problems up here for a while. His carb loaps along under load. It used to run like a sewing machine. We sort of suspect it is the carb but have decided to replace plugs, dist. cap, wires, etc. to take them out of the what if catagory. Does anybody have any ideas on the tune up specs for these things?

    We need to know Timing
    point gap
    etc.

    He's interested in putting in an aftermarket pointless ignition.
    I don't really know much about the motor and he knows less.
    It has an updraft Zenith Carb.

    Thanks for any clues.
     
  2. Ike
    Joined: Apr 2006
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    Ike Senior Member

    What boat is it? You said woodie. That tells us very little. Who built it? Garwood? Chris Craft?
    You may want to contact the Antique and Classic Boat Society in Clayton NY, http://www.acbs.org/. They probably know a contact thaat these engines.
     
  3. TollyWally
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    TollyWally Senior Member

    The boat was built in Seattle in 1930. It is an Admiral. It was repowered with this motor at a later date. I believe my questions are more motor specific than boat specific. It is a beauty though. Very curvaceous. It was the boatyard owners personal boat for many years. I'll try to upload a pic in the next couple of days. Thanks for the tip. I'll wonder over to that site and see if they have any old motor specs.
     
  4. thudpucker
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    thudpucker Senior Member

    You guys may be in for more shocks.
    If they've been running salt water through that motor the block may be rotted out around the exhaust valves and between the cylinders at the narrow parts.
    As I recall the points were .016 or so and the timing was pretty liberal. About Six or eight degrees before TDC. I think you can find that stuff on the internet. Probably Google.

    If he's not getting any interference in his radios, I wouldnt fool with an electronic ignition. Nothing in the industry is more stable than the original (kettering) ignition that came with that engine. You cant improve the performance of that engine with any aftermarket or recent inventions.
    It'l run forever as long as the block is in good shape.

    If you cant get the engine to idle well, try adjusting the Idle air screw. If that does not work, you have other problems.
    For instance if the Idle air adjustment does work, you can make it better and worse and find a happy medium but the engine still idles rough, you may have a vacuam problem.

    The Throttle valve shaft in those old updraft carbs would wear. That left a lot of leakage and getting them to idle well was impossible but the engine would run ok at speed.
    The gaskets in those old carbs would dry out and leak.

    As a kid working in a yard on Lake union, we pulled three, 8 Cylinder Crowns out of an old Chris craft. We took them down to parts and carried the pieces up the steps by hand.
    But when it came time to put the new engines in, the upper decks had to come off.
     
  5. thudpucker
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    thudpucker Senior Member

    "loping along under a load..." I missed that part.
    I believe you have an adjustable main jet in that carb.
    It looks like a little brass 'T' handle sticking out of a brass jamb nut about in the curve of the carb throat.
    Count the turns as you move that 't' handle.
    If Ethanol has done any eroding of the brass, it would be where that long slender needle goes through the hole in the jet.
    The common way to 'clean' that jet was to unscrew the long needle, then put it back in. You adjust that one till it runs good under a load.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It's very probable that the rubber parts in your fuel system are breaking down from the ethanol (common problem). It will again run like a watch if you replace the rubber pieces with ethanol resistant pieces. If you can't do this, rebuild the carb, then insure the fuel system is drained completely after each use, to prevent future issues.

    I'm sure someone makes an electronic conversion for that distributor, though it really isn't necessary if you get the engine healthy. They run forever and I've seen them hold onto points until there wasn't any contact left (many years). Ignition issues are usually related to weak coils, bad wires, wobbling distributor shafts, owners that leave the key "on", etc. not points or condensers.

    As to tune up specs, it's really a matter of which Chrysler Crown you have.
     
  7. TollyWally
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    TollyWally Senior Member

    Thanks to each and every one of you. I have not yet been able to find the wealth of information I thought I could find on the internet. LOL. I will take all of these ideas dockside and see what there is to see.
    Again thanks everyone. Feel free to add any more info if it comes to mind. In the kingdom of the blind, I'm needing a flashlight! :)
     
  8. thudpucker
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    thudpucker Senior Member

    One more!
    Par reminded me of this one, at some time an after-market Carb kit may have been used, which had one of the Needle valves with the Rubber Tip.
    Ethanol may be affecting that rubber tip, making it stick, and fuel pump pressure is needed to force it open.
     
  9. PAR
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    PAR Yacht Designer/Builder

    A lot of older equipment is having difficulty with ethanol. I've had to replace needles, pump diaphragms, lines, etc. Pull the needle from the seat and if it's tip looks grayish black, it's rubber and prone to this problem.
     
  10. thudpucker
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    thudpucker Senior Member

    That Zenith up-draft carb had a leather fuel pump, and cork gaskets.
    Both those were prone to failure. I used to replace both of them.

    The screws holding the Throttle Valve and Choke plate were removable.
    If they got loose, the vibration of the engine rattling the choke plate and especially the throttle plate against the bore of the Carb intake caused some ridges to develop which caused an air flow interuption or a burble which made atomizing kinda hit n' miss. It'd smoke at midrange and some times at full throttle.

    I just wonder about the brass they used back then and that Ethanol of today?
    Its surely possible the float has been eroded and may have holes eaten in it. Needle n' seat are eroded and rough and dont shut off the fuel causing a little flooding at hi rpms which might explain the loping at speed.

    Of course it could also be a dying fuel pump or the pump sucking air from a crack or the vent to the tank partially plugged as well.
     
  11. PAR
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    PAR Yacht Designer/Builder

    It could be one or a combination of several things, but any reasonable mechanic should be able to sort it out.
     
  12. hartley
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    hartley Junior Member

    you do not say the approx year of the chrysler,they have been around since the early thirties.however post war copies of the "rudder'' advertise 3 chrysler marine engines they being the ''ace'' the ''crown'' and the ''royal'' the ''ace'' number of cylinders not specified ,the crown was a 6 cylinder the royal was a 8 cylinder . some information from this side of the globe ,the chrysler crown marketed here was the 250 cubic in version of the venerable chrysler side valve engine ,this engine in various capacities ,230 cubic in being common was was marketed in various dodge plymouth de-soto cars and trucks . tune up spec's for the 250 cubic in version are ....
    ignition points gap 014-016 in
    dwell angle 32 deg + or- 2 deg
    tappet clearance(hot engine) inlet .008in exhaust .010in
    plug gap .028 to .032in
    oil pressure 30 to 50 lbs at 2000rpm
    hope this helps ,cheers hartley
     
  13. thudpucker
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    thudpucker Senior Member

    Cheers for Hartley.
    To adjust the valves, you needed two (sorta) special 9/16's open end wrenches. Very thin, and two diferent lengths. Four wrenches in all.
    They have to be made of good stuff too. I doubt you'll find them these days.
    My wrenches came from Sears.
     
  14. TollyWally
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    TollyWally Senior Member

    Indeed cheers for Hartley! So Sears doesn't sell these wrenches any more? If we can't buy them we'll have to make them. Are the design specs obvious once you pull off the valva cover?
     

  15. thudpucker
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    thudpucker Senior Member

    LOL, Tolly your in for a treat when you attack those valves.
    I wouldnt until I'd taken a compression test to verify you have at least 100Lbs of compression and no two adjacent cylinders with less compression than the others. The limit is 25% less.

    The valves are down the side of the block. On an Auto engine I have adjusted the valves with the manifold in place, but on a Boat engine its not possible. You have to take the Manifold off to reach the valve covers.
    Setting them cold will work ok. Looser is better than tighter.

    IF...a big if here....you have to do the valve adjustment, look at the sludge in the valve lifter part of the block. If its built up, Caked and cracked like the Desert mud under the sun, it's telling you the engine has not been running up to temp and the oil hasnt been changed often enough.
    Dont bother trying to clean all of it out, just enough to do the work.

    We still dont know if they are running salt water through the block for cooling?
    Salt water Thermostats should be down around 140 Degrees. If its fresh water cooled keep it up around 190.
     
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