360 clean up for my Skybolt

Discussion in 'Lycoming & Continental' started by taff, Dec 2, 2015.

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  1. Dec 2, 2015 #1

    taff

    taff

    taff

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    Thanks again for the help I received acquiring my sump.
    I media blasted with walnut shells and now painted along with the accessory case.

    All other parts are back and now I can spray the crank case.
    I had full inspection of the case a reworked crank and cam shaft.
    Inspection and chromed cylinders and new pistons and connecting rods.

    I'm not working on the engine, a friend of mine is doing that part.
    A couple of pictures so far.

    DSCN3555 (800x600).jpg

    DSCN3553 (800x600).jpg
     
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  2. Dec 29, 2015 #2

    taff

    taff

    taff

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    I painted the case today. The air was dry, no wind and moderate temperature. Good opportunity.

    Now the mechanic can start building for me, when he has the time.
    Pictures of the etch primer and polyurethane top coat color.

    DSCN0055 (800x600).jpg

    DSCN0056 (800x600).jpg

    DSCN0058 (800x600).jpg
     
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  3. Jul 11, 2017 #3

    taff

    taff

    taff

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    An update on the progress of my engine. December 2015 was the last post and now we are building the engine.
    Not an issue with time because I have had many other things occupying me time.
    But I am glad that I had the engine components sent away and worked on at an earlier time. Now everything is ready for the rebuild.
    When will it be on the airframe? maybe soon but there is still the expensive stuff I need to manage. Like fuel injection system, constant speed prop overall and governor and a boat load of other items.

    I am happy my buddy is doing it and I am helping 'cause I am clueless!
    A couple of photos from today.

    DSCN6138 (1280x1030).jpg

    DSCN6139 (1280x959).jpg

    DSCN6140 (1280x1020).jpg
     
  4. Jul 11, 2017 #4

    IanJ

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    I've always wondered about this: isn't paint effectively an insulator? I know it can't have much effect in a coat this thin, but it always looked odd (for cooling reasons) and lovely (for appearance's sake) to paint the cylinder fins.
     
  5. Jul 11, 2017 #5

    Don Adamson

    Don Adamson

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    Eric,
    You will need to fabricate a 1/4" spacer for the intake tubes where they meet the cylinder when using that sump. Not a problem, it has been done many times before. Also you will need longer studs or replace with longer bolts.

    I paint all Lycoming engines, 'cause the manual says so (to prevent corrosion).
    I don't paint where the starter contacts the engine.
     
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  6. Jul 11, 2017 #6

    cwilliamrose

    cwilliamrose

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    I suspect paint is less of an insulator than corrosion.
     
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  7. Jul 11, 2017 #7

    taff

    taff

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    I don't understand "isn't paint effectively an insulator?"

    It would need to be quite thick to insulate (maybe over 1/2")

    But on an engine I can't see it insulating. Heat would transfer through the coating and radiate outwardly, no matter what color the engine is sprayed.

    The heat radiated could be reflected back from the engine cowling. So maybe a white color interior to the engine bay would reflect heat back to the engine.
    If the cowling interior is painted black, this could absorb the heat? I have never tested this theory.

    We know that the infra red radiation of the sun will be absorbed with dark colors and reflected with light colors.
    Examples are; light color (white) T shirts as compared to black T shirts are cooler for you under the sun.
    A white car can be 50 degrees F cooler that a black car on the metal surface.

    So there is a difference between heat transfer or reflection or absorption.
     
  8. Jul 11, 2017 #8

    taff

    taff

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    Don. Thanks for the feedback.
    I will remove the paint where the starter contacts the crank case. Is this for circuitry issues?

    As to the intake tubes, I placed them on today. Not permanent, but only to see how things fit and line up.

    As far as I can tell I should have no issues. There is a little slop and that should close up with the gasket in place. The studs protrude the flange enough for the nut and washers.
    If there is something I am missing please let me know.
    Cheers.

    (The green masking tape is there, that has the cylinder #'s ID'd in pencil)

    DSCN6144 (1280x960).jpg

    DSCN6145 (1280x960).jpg
     
    Last edited: Jul 11, 2017
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  9. Jul 12, 2017 #9

    Neil

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    Make sure the intake tube flange sits nice and square to the head or they won't seal off and if the tubes are in any sort of a bind the result will be intake leaks and eventual fractures of the tube flange like in this photo.

    Intake tube fracture.jpg
     
  10. Jul 12, 2017 #10

    IanJ

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    An insulator is an insulator, no matter how thick or thin. How much it insulates usually varies with thickness. If I had to guess, I'd say that a typical coat of engine paint affects the engine's operating temperatures by a tiny fraction of a percent.

    I wasn't saying it shouldn't be done, just expressing a thought I've had before when looking at nicely painted engines. I agree that it's the right thing to do, and my thought about it being an insulator is basically one of those, "Consider a cow: for the purposes of this discussion, the cow is a perfect sphere," kind of theoretical discussions that has no bearing on reality. :D
     
  11. Jul 13, 2017 #11

    taff

    taff

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    I was saying that paint on an engine is part of the heat source and not insulating (or hindering) the heat from radiating or transmitting from the source.

    Think of the old cast iron hot water radiators found in old houses.
    These were painted and not considered as being insulated.

    Now back in the day, the house that contained all these radiators was not insulated very well and considered a money pit because it cost a fortune to keep heated. Insulate that house and the heat stays in. :D
     
  12. Jul 13, 2017 #12

    Lotahp1

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    I will stoke this fire....

    After I got my case back from Divco on my Ranger I started to wonder about paint also and what the shops like Barrett, Covington, Radial Engines, etc etc do. So I called Covington first because I know how nice there engines look first hand. This is what they told me

    1) Have the case etched and alodined.

    2) prime case with a Thin coat of rattle can zinc chromate. (Yeap I was head scratching here too)

    3) top coat with your fav color of PPG Concept polyurethane single stage.

    They said they have used epoxy primers under it etc BUT it insulated to well and they had heat issues. So just use a thin layer of rattle can zinc chromate and it breathes better than a thick coat of epoxy primer.


    Now to add to this...I am restoring a 1978 Porsche 911sc for my son. And my amazement the engine and the transmission is bare aluminum. They used some sort of "conversion coating" like alodine but no paint at all. I etched with AC12 and alodined the exterior of the transmission and the engine. Per there book you are suppose to apply some sort of corrosion preventive compound every so often, like every 6 months to the exterior surfaces. Ya. I bet that got done on exactly zero cars. Anyway...das Germans didn't like paint either. I'm guessing but I assume it was because of cooling.
     
  13. Jul 13, 2017 #13

    smizo

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    Barrett didn't paint my cylinder heads for what its worth..........
     
  14. Jul 13, 2017 #14

    Lotahp1

    Lotahp1

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    Come to think of it on the actual cylinders...I had a C-85 rebuilt for my buddies cub recently and i did the case like I mentioned in last post and had them paint the steel barrels of the cylinder but only etch and alodine the cylinder head.

    Since they stick out on a cub...my thought was paint always flacks off and is hard to clean baked on bugs off of.

    View attachment ImageUploadedByBiplane Forum1499952474.031171.jpg View attachment ImageUploadedByBiplane Forum1499952529.846962.jpg View attachment ImageUploadedByBiplane Forum1499952677.919859.jpg View attachment ImageUploadedByBiplane Forum1499952741.734446.jpg
     
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  15. Jul 13, 2017 #15

    taff

    taff

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    I painted my crank case, sump and accessory case with a two part zinc chromate primer I thin coat,= 0.3 thousandth (.3mils) film thickness.

    Then I sprayed 1 thin and one normal coat of a two part polyurethane,
    = + - 1.5 thousandth (1.5mils) film thickness.

    When I received the cylinders back from the company that inspected and serviced them. They used an alkyd paint (synthetic enamel). (the stuff that washes off with MEK and scratches off easily) I think this is what is generally used in the industry.

    I was talking about insulating or not.

    Like everything else, there will be different opinions on this. For example Lycoming paints engines while Continental only treats with phosphate.
    Modern cars have treatment on their engines (I don't know what, otherwise the bright aluminum would corrode and start turning grey / white) And big block, older muscle cars have their engines painted.

    I would not use an epoxy, probably would not hold up to the temperature
     
    Last edited: Jul 13, 2017
  16. Jul 13, 2017 #16

    taff

    taff

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    Chris, did they give a reason why?

    This is getting curious stuff :D
     
  17. Jul 13, 2017 #17

    IanJ

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    This all tends to support my theory that paint is an insulator, though I still think it would only have a tiny effect. I would hope that we're all discussing an interesting concept, not debating what should be done in the real world. As Don mentioned above, follow the engine manufacturer's manual.

    My BMW airhead motorcycles all had bare cylinder fins, which is what got me started thinking about it. My CL175 racebike did as well, now that I think back. Some racers painted their fins, but most didn't. I'm not sure how any of the engines were finished. I stripped off any finish on the racebike engine as part of my rebuild efforts, but didn't re-coat with anything. It didn't see corrosive conditions enough to see any problems.
     
  18. Jul 14, 2017 #18

    Beej

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    ECi painted mine. That's the maximum participation from me on this subject. :)
     
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  19. Jul 14, 2017 #19

    taff

    taff

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    Well said! I'll wholeheartedly go along with you on that.
    Over and out.:D
     
  20. Jul 14, 2017 #20

    crankyklingon

    crankyklingon

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    I painted mine.
    Didn't paint the heads on my Bonanza engine when I did it simply because they weren't painted when I pulled them off.
     

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