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  1.  
    Hi everyone.
    I have built many very nice running engines (all lapped with splash oil accept this one) and am having an issue I just cant seem to lick.
    I have a Howell Powerhouse with drip oil that I just cant keep a set of rings in.
    Using cast iron make a perfect set of rings with the trimble method (the one I have used for years).
    Engine will run perfect in the break in period with great compresion then I loose ALL compresion.
    I have narrowed it down too two things...
    Ring gap is too large....
    Or I am using an insufficient tensile strength material ....(considering trying a ductile cast iron)
    Are all of you using simple fine grain grey cast iron ?
    And what are your thoughts on a ring gap of .006 ?? and a piston ring diameter .0009 tenths smaller than the bore...should I consider a gap of almost zero and OD grind my rings to a couple tenths ??
    My thoughts are that my gap is too big and over time the rings become weak and simply bows into my land clearance....And I assume I would not notice this problem in the other engines due to the lapped surfaces with splash oil.
    thanks for any help you may be able to provide this one has me stumped !
    Mike Walters
    • CommentAuthorgbritnell
    • CommentTimeApr 21st 2011
     
    Hi Mike,
    I also use the Trimble method for making my rings. The iron I use has a trade name of Durabar. At one time it was proprietary but I guess there are equivalent materials out there now. It is a very fine grained iron. I make my rings the same size as the bore, or as close as my measuring tools will allow. As far as ring end gap, for a 1.00 bore engine I try to keep the gap at no more than .003-.004.
    How does your bore look after you lose compression? I can't imagine the rings wear that quickly as to lose compression.
    My 4 cylinder OHV engine and my Holt both use a splash oil system and I have never had any issues with the rings. In fact as the rings seat in the compression get greater.
    gbritnell
  2.  
    Mike:
    What is the cylinder ( liner) material ? Cast Iron Vs Steel, Steel can take longer to develop a nice seal, and sometimes develop a glaze, which need removing before using new rings.
    Gap in the rings is a bit big ( my 2 cents), I try to get the gap as small as practical, around 1-2 thousands, then runt he engine and when the rings wear into the cylinder the gap should increase ( Have not measured by how much).
    Rings diameter as close to the cylinder liner diameter as possible.
    Cast Iron Durabar 6000 is the one I'm using, a friend bought a good amount of it and I inherited part of it.
    Can you check your heat treating temperature, you may not be reaching the correct temperature for allowing the CI to retain the desired shape in the retort, and they may be return to original size after a bit of warming up by running in the engine.
    Can you measure the amount of spring force needed to compress one new ring vs a used one.
    Another area, though not likely ring groove in piston too small, ring sticking to the piston?

    Regards.
    JAime
  3.  
    The thing that jumps out at me the most is making rings .0009 smaller than the bore. I believe that rings should never be smaller than the bore. As close as possible without going under.
  4.  
    Mike,
    What do the failed rings, and cylinder look like after compression is lost. Did the failed rings make good 360 degree cylinder contact? Is the cylinder still perfectly round and unscored? I always make rings at the cylinder bore diameter with a ring gap of .002-.003" gap per inch of diameter. What is the piston ring side clearance? It should be as close as possible with free ring movement (.0005"-.0015").

    When you put this engine back together next time I would use a 50:1 ratio of fuel/Marvel Mystery oil mix during break-in. Jerry Howell recommended using a 50% MMO and 50% synthetic oil for the drip oiler on this engine. How many drops of oil per minute are you using? Drip oilers are not the best cylinder lubrication means for a medium speed engine if it gets run fast very often. I would always use a little oil in the fuel, and don't run this engine too fast.

    Jeff
  5.  
    I should maybe clarify "ALL" compresion.
    My engine will run very well for a while and it then will loose enough compresion too not start well and flood etc due to the lack of combustion (time and time again) this time I am using a steel cylinder with aluminum piston and grey cast rings.
    I have narrowed my issue to my ring gap....My side wall clearances may be a little wide as well (.002 per side).
    I am going to redo my process exactly the same with some of the info you have all posted her and try again.
    After much running with the outer diameter of the rings eight tenths small and a five thou gap the rings have ended up giving me the best results yet....but certainly they could be much better.

    My next step......
    Bore gauge my cylinder diameter
    Make new rings the exact diameter of the bore (+-.0005)
    Lap the rings to a snugger fit in the piston ring grooves.
    And I will use a .0015 gap.
    I have researched dura bar cast previously it provides very high tensile strengths compaired to regular grey cast......I intend to buy some and use it in the future.
    I must admit I will be a little anoyed with myself if all of my problems getting a good seal stem from a simple piston ring gap !
    All of my other lapped cylinder engines with splash oil run great and have maintained perfect compression for many years.....so this issue has been haunting me !
    I will keep you all posted.
    thanks allot for your advice.
    Mike Walters
  6.  
    2 things Mike

    I am unsure of the bore in this engine but 1.5 thou seems like less than you want. .003 would be the smallest I would go.
    +-.0005. . . . Not minus. Go as close to your bore as you feel comfy going without going smaller. Never go smaller.


    These are rules that I follow for myself. It's your engine and what ever you decide to do, best of luck and I hope these changes work well for you!!
    • CommentAuthordavid
    • CommentTimeApr 24th 2011
     
    On my last vertical with 1 inch bore, I used an aluminum piston, iron sleeve, Iron rings. I made the ring OD as exactly the bore size, split and expanded . I only put a gap of about 0.001 and the rings shattered. I doubled the gap, by eye because the break was not true. The rings worked fine but the engine would slow after a few minutes. The aluminum piston appeared to be scored. I reduced the piston ID for 0.002 clearance and it has been fine ever since
    David
  7.  
    Hi everyone
    I have made some discoverys with my rings in this particular engine.
    First of all I am now less concerned with my method and tollerances and more concerned with my material selection and my oil delivery.
    I have come to the conclusion that oil (better yet the lack of oil) is my biggest issue hence the rings not working after hours of running.
    I am re making rings hopefully for the last time using durabar 80-55-06 ductile iron which boasts a very fine grain and holds a tensile strength of 80 000 psi and a yield strength of 55 000 psi.....It is also heat treatable with oil to 50 RC or so.
    These values FAR exceed regular grey cast iron.
    I am also going to mix 2 stroke oil in my fuel at a 50/1 ratio
    Hopefully the new high wearability cast and more oil will allow me ongoing consistant compression.
    I will keep you all posted
    Mike Walters
  8.  
    Mike,
    Most 2 cycle oils are made for high reving engines with high exhaust temperatures. The 2 stroke oil won't burn well in an engine like the Powerhouse,and will just start exiting the engine exhaust as a black goo. I suggested MMO as it has worked for me at 70:1 in my slow running 4 stroke as most of it burns off, although I still get some wet stacking. You might also want to read Bob Shore webpage. He really liked a fuel mix with WD-40. It works well with camp fuel in some engines. A slow running engine doesn't need much oil in the fuel to lube the cylinder. With a little experimenting, you'll find what works best.

    Jeff
    • CommentAuthorgbritnell
    • CommentTimeMay 10th 2011
     
    Hi Mike,
    I have several hit and miss engines that use a drip oiler. The pistons are aluminum, the rings and cylinders are iron. We have already discussed ring and piston clearances. The only time I ever mix oil with my gas is when I first break the engine in and I don't even know if it's necessary, it's just something that I do. After that I just use straight gas (86 octane). I have never used Marvel Mystery Oil but have heard of fellows using it. I don't know what the properties of it are so I'm not even going there. What I can tell you from years of experience in working with 2 cycle motorcycle engines is that first, no matter what kind of oil you use to mix with your gas it won't burn. Oil has virtually no combustible properties. If you add or subtract oil from a 2 cycle gas mixture what you are doing is leaning or richening the mixture. As more oil is added to the gas it leans the mixture, more oil, less gas can pass through the metering jets so therefore it leans it out. What I'm getting at is no matter what kind of oil you use it won't burn. With today's high quality synthetic 2 cycle oils I would opt for one of them. For a slow running hit and miss engine you can mix it to 60:1 and you will get virtually no residue. I would still use the drip oiler but adjust it for a very small amount.
    gbritnell
  9.  
    The pre mixed oil has solved my issues to this point.
    Its a bit more messy as like it was stated the oil wont burn it just drooles out the back of the cylynder, I started with the 60:1 ratio and think I will take some more oil out yet.
    I have yet to recieve my grade 80 dura bar so I have actually solved the issue with extra oil using grey cast.
    The engine starts from cold nicely and maintains a steady idle, were as before it was very eratic at best.
    I have learned allot about this style of engine and realise that some of my assumptions from other build expieriances fogged the tru issue.
    This is a great engine (Jerrys plans are second to none) and I am glad I have finally figured out the bug.
    Four hours continuous running on it to this point and the compression keeps getting better just as it should.
    Thanks again everyone
    Mike Walters
  10.  
    That's good news!! Happy motoring!
    • CommentAuthorernie7
    • CommentTimeMay 15th 2011
     
    I made several Jan Ridder's engines, and they run. The cylinders and pistons are both cast iron (Speedy Metals). Both have been lapped for a very tight, but smooth acting, pressure seal. I use straight Coleman fuel. I''m now in the final stages of building the Howell V4 and intend to use the same technique as the other engines I made. So much easier than pistons with rings. If the engine will not run I cn always go back to the aluminum piston with cast iron rings.