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Thread: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

  1. #1
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    Default Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    Hello All,

    I'm looking for the torque value for the Manifold on a Chrysler Marine Flathead 6 Crown M47S..

    I know it's 57 lbs. for the head but I just can't find the Manifold torque....

    Thanks Much,
    Mike
    Eagle River, Wisconsin

  2. #2
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    I donít think you are going to find specs for that in the manual. Back Ďthení many details like that were assumed knowledge.
    I even just found conflicting information on the head nuts, 57 as you posted (and is what I used), and then also 70 in a different area.
    Last edited by nedL; 11-24-2018 at 08:48 AM.

  3. #3
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    nedL,

    I too found conflicting poundage for torquing the head back on.... 57 and also 70...

    Assumed Knowledge.....I still don't know what to assume.....

    Mike
    Eagle River, Wisconsin

  4. #4
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    Tight enough, but not to tight. (Haha)

  5. #5
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    I run into this all the time. and common knowledge is a torque chart. It is usually more important that they be "the same, or alike" than any specific number. Whether a head or a manifold it is typical to start at the center and work your way toward the ends, like ironing out a bedsheet...
    Exhaust manifolds cycle with heat and do change length, often they are made in sections to allow movement, and sometimes not. The torque specs for those are usually less to allow the manifold to "slide" a bit as it heats and cools. Otherwise they will crack. They often use locking tabs or devices to secure them because of the low "torque" or tightness.

    edit; I did find a note saying if the cylinder head is equipped with studs, the nuts are 55 ft/lbs, if capscrews, 70 ft/lbs

    Quote Originally Posted by Canoeyawl View Post
    It generally considered safe to use a standard torque chart by bolt size and type. In automotive work it would be unusual to find a fastener with less strength than "grade 5". "Grade 8" is common for head bolts, main bearings, and reciprocating components.


    Last edited by Canoeyawl; 11-24-2018 at 12:12 PM.

  6. #6
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    Quote Originally Posted by Canoeyawl View Post
    I run into this all the time. and common knowledge is a torque chart. It is usually more important that they be "the same, or alike" than any specific number. Whether a head or a manifold it is typical to start at the center and work your way toward the ends, like ironing out a bedsheet...
    Exhaust manifolds cycle with heat and do change length, often they are made in sections to allow movement, and sometimes not. The torque specs for those are usually less to allow the manifold to "slide" a bit as it heats and cools. Otherwise they will crack. They often use locking tabs or devices to secure them because of the low "torque" or tightness.

    edit; I did find a note saying if the cylinder head is equipped with studs, the nuts are 55 ft/lbs, if capscrews, 70 ft/lbs
    The industrial version of the engine was produced until 1978, so farm equipment parts might be compatible and more readily available.

    https://www.hemmings.com/magazine/hm...x/3749639.html
    "Industrial versions of the venerable flathead continued to appear through the 1970s, and the Power Wagon was produced for export markets until 1978. The 25-inch engine remains very much a part of the American collector-car scene."
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  7. #7
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    Quote Originally Posted by nedL View Post
    Tight enough, but not to tight. (Haha)
    An oldtimer mechanic I knew (he's long gone now) had a neighbor who was always asking for advice, but would never pay him to do the work. One day when a friend & I were visitin' (aka having a few beers), the neighbor came in & asked "How tight should I go on the head nuts on my Farmall?" He looked him straight in the eye & said "Just as tight as you can with a 12" wrench - then 2 more turns"

    I heard later that he broke 4 studs off before he caught on.

    Now that I have that out of the way, I too would go just a bit looser than the chart calls for - to allow for movement (as mentioned).
    "If it ain't broke, you're not trying." - Red Green

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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    It just occured to me that your exhaust manifold is most likely water cooled. If so, disregard what I said above about the heat, it is not really applicable if the manifold is water cooled.
    I would treat them like any other grade 5 bolt...

  9. #9
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    Quote Originally Posted by Canoeyawl View Post
    It just occured to me that your exhaust manifold is most likely water cooled. If so, disregard what I said above about the heat, it is not really applicable if the manifold is water cooled.
    I would treat them like any other grade 5 bolt...
    jeebus, you guys.

  10. #10
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    Default Re: Torque value for Mainifold Flathead 6 M47S Crown Chrysler Marine Engine

    Ok, you guys, I have been watching this thread for some time. I made a comment when the original poster first surfaced, but it was disregarded. I will offer a suggestion again. I don't want to argue and will not. However, please note that this advice is informed by 35 years of boat restoration; most of that was on runabouts.

    I am baffled as to why the poster would start restoration work by working on the engine. Even more mysterious is his choice to work on the engine in the boat. Why? It takes a couple hours to remove a boat engine. Why not do it? Your back and knees will thank you.

    If I were doing this restoration this is how I would proceed. (And I have done a few of this model.)
    1. Remove engine. Store it in a corner of your shop. Until you have had a chance to think carefully about how to proceed with power.
    2. Remove cockpit sole and inspect very, very carefully the bottom of the boat.
    3. Centuries are notorious for having rotten bottoms. The reason for this is that they have batten seam bottom and the batten prevent water from limbering down. Water get hung up along each batten and this promotes rot. Also the transom on this boat is curved. The lower and upper transom frames are up of three pieces of white oak. Unfortunately, these were glued with plastic resin glue. There is a 100% failure rate with these laminations. At least I have never seen one which has not delaminated and rotted. Replacing the bottom is a huge job. I have not done this job in years but my guess is that it would be between 10 and 20k. Some come back with a so-called "Chris-Craft bottom." These are double planked with plywood on the inside and plank on the outside. This will eliminate the standing water/rot issue.
    4. Replace topside and deck planks as required.
    5. Fair, sand and varnish hull.
    6. Consider the engine. Crowns were good engines in their day. They were made from the mid 30s to the 60s. Thus, the engineering on these engines is going on a hundred years old! The engine was not running and you have no idea of its condition. Before proceeding it should be completely disassembled Magnafluxed to check for integrity by a knowledgeable machine shop. There is a very slight judging advantage for original engines in the ACBS judging criteria. However, most knowledgeable potential buyers are going to prefer a more modern engine. Yes, some vintage engines add value. A Crown does not. Also, if you stick with the Crown you will have to provide 12volt power if you want modern systems. (There is no penalty for using 12 volt systems.) You will be much, much happier with a reliable power plant. By the way, don't assume that automotive parts with work on marine engines. For example, marine engines have a different cooling path and the head gaskets are different.
    7. Join the ACBS and network with people that actually own these boats. You are not being well served with advice here.
    Again, I don't want to start an argument, but it is troubling to see you guys wandering in the wilderness with this project. Hope you can put some thought into further efforts. Thank you.

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