Teflon coated piston skirts - NCRS Discussion Boards

Teflon coated piston skirts

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Mike T.
    Very Frequent User
    • August 31, 1979
    • 120

    Teflon coated piston skirts

    I'm getting my 69 350 rebuilt and the rebuilder said he is going to use "Sealed Power" pistons with Teflon coated skirts.
    I'm unfamiliar with that so I wanted to ask you guys. I don't want to use some "new technology" that we find out "flakes off in 10 years" or something else.
    So what do you think? Is it a good idea to use Teflon coated skirts or should I go the conventional route? Thanks!!
  • Al R.
    Very Frequent User
    • June 30, 1988
    • 687

    #2
    Re: Teflon coated piston skirts

    I'd go conventional unless you are planning to use it for racing. As others will point out, the Teflon is for reducing friction, which in turn increases horsepower. For a street engine, this would be a waste of money that could be used elsewhere on the 69.

    Comment

    • Duke W.
      Beyond Control Poster
      • January 1, 1993
      • 15672

      #3
      Re: Teflon coated piston skirts

      Sealed Power is a Federal Mogul brand, so okay to use, but you should verifiy that it's the proper OE replacement part number, so you don't end up with a low compression engine.

      I think the Teflon coating is primarily a break-in aid to help prevent piston scuffing - similar to Parkerizing camshafts, and it will gradually wear away with use and without consequences. I think the LS6 had Teflon coated piston skirts and maybe some other LS engines, so it's mainstream technology.

      What other parts does he want to sell you? How about machining operations? I bet some are either unecessary or not correct OE replacements.

      Turning over your engine to "rebuilder" without a proper plan is a recipe for disaster. The archives are full of horror stories.

      Duke

      Comment

      • Bob W.
        Very Frequent User
        • December 1, 1977
        • 802

        #4
        Re: Teflon coated piston skirts

        Mike I agree with Duke. Some builders will try and sell you stuff you don't need . So when I have a motor rebuilt I know what I want done,

        No more no less.

        Bob

        Comment

        • Tom P.
          Extremely Frequent Poster
          • April 1, 1980
          • 1815

          #5
          Re: Teflon coated piston skirts

          Originally posted by Bob Winters (1653)
          Mike I agree with Duke. Some builders will try and sell you stuff you don't need . So when I have a motor rebuilt I know what I want done,

          No more no less.

          Bob
          And I totally agree with this-----------------------PROVIDED YOU CAN BUILD YOUR OWN ENGINE! Engine building is NOT rocket science! Of course, you need to use a machine shop that you have total confidence in. Have all the machine work done that you want done (tell the machinist what you want, DO NOT tell him HOW to do it!!!). Then bring all the parts home and do your own assembly.
          Now, with that said, I fully understand that not everyone has the time, space nor desire to build their own engine, Fine, then you have to rely on a competent engine builder.
          As mentioned, machine shops want to sell you stuff that really isn't needed. One of the best examples is surfacing the block decks. We all know that destroys any stamped numbers/codes and eliminates the broach marks. Machinists will oftern tell you that the block needs to be surfaced to assure that it is perfectly flat. I SAY BALONEY!!!!!!!! If the block-gasket-head interfaces were not leaking when the engine was torn down---------------THEN IT IS STILL FLAT!!!!!!! DUH! Personally, I don't want anything removed from the deck surface bacause I want all the thickness I can get from a cylinder deck surface. If the cylinder deck/head surfaces were flat when disassembled, a good composition head gasket will seal almost anything.
          Personally, I like pistons with the teflon coated skirts. For a street/driver/performance engine, are they really needed? Probably not, but anything that can be done to reduce friction is a plus.

          Comment

          • Duke W.
            Beyond Control Poster
            • January 1, 1993
            • 15672

            #6
            Re: Teflon coated piston skirts

            It's best if an owner can do his own disassembly and assembly, and this begins with what I call a "forensic teardown", which includes measuring deck clearance of all eight cylinders before the piston rod assemblies are removed to get a handle on the compression ratio management task. Head and block level is easy to check with a machinists bar and .0015" feeler gage. A basic rule is "remove no metal unless absolutely necessary."

            The owner should discuss the rebuild with the shop to make sure they understand what should be done and not done, and a specific set of instructions and parts list should be prepared by the owner and attached to the work order. The parts list should include manufacturer and part number of any part that MIGHT need to be replaced, and it's not that long.

            I have detailed documents on this process that I send to those who are interested.

            Duke

            Comment

            • Tom P.
              Extremely Frequent Poster
              • April 1, 1980
              • 1815

              #7
              Re: Teflon coated piston skirts

              Maybe it's good, maybe it's not. But I purchase ALLLLLLLLLLLLL my parts, usually by mail order. I determine what is needed, then order them-------------USUALLY at a substantial savings over what it would cost to have my machinist buy them and then tack on his markup.
              Before ordering pistons/bearings, I have my machinist determine how much the cylinders will need to be bored and how much the crank will need to be turned. Once that determination is made, I order the needed oversize pistons and the undersize bearings. I RARELY replace the oil pump, but everything else gets replaced: cam, lifters, cam bearings, timing set, freeze plugs, rod bolts, (and I usually replace main cap bolts with studs) gaskets, etc, etc. My machinist resizes the rods, installs new bolts, fits the pistons to the bores, installs the pistons on the rods, balances the rotating assembly, then I bring it home and do a very precise assembly. And again, building your own engine IS NOT rocket science! I also build my own (and customer's) 4spds, rearends, suspensions, brakes and FI units. There is no better satisfaction, and as they say, if you want something done right, do it yourself.

              Comment

              • Jack H.
                Very Frequent User
                • April 1, 2000
                • 477

                #8
                Re: Teflon coated piston skirts

                Specific to the original question, I'm not sure about 350 pistons, but in the 327 hi-po configuration you don't have a choice of teflon or non-teflon at least in the L2166F (HiPo 11:1) SealedPower/FedMogul/SpeedPro quality brands I prefer. So, I don't think its a question of should I use teflon coated or not. I'd be surprised if your rebuilder had a quality alternative that was non-coated unless he found some pricey NOS units. And as Duke has already noted, I don't think the teflon is at all bad, consequential, or not wanted for any reason...not to mention the other things that are more important to worry about in this endeavor.

                Comment

                • Mike T.
                  Very Frequent User
                  • August 31, 1979
                  • 120

                  #9
                  Re: Teflon coated piston skirts

                  Thanks Duke, Tom Bob and Al.

                  This engine rebuilder has a great reputation and has been around for 30 yrs. that I know. Several of my buddies have used him through the years and highly recommend him. He runs the entire operation by himself in his shop behind his house. I visited him when I dropped the motor off and discussed his work and his views on things. He understands the importance of pad stamps and broach marks. You would think you were talking to an NCRS guy with a SWC in his garage instead of his red/red 63 Impala 409. I definitely trust his commitment to originality and matching numbers.

                  My motor had been left outside and was seized from rust, both throughout the intake and in the cylinders. When I took it over to him, I brought the head gaskets and he recognized them as being factory originals. He mic'd the cylinders and sure enough, it was the original bore. He is optimistic that he can clean it up at .020 over, but confident .030 will certainly be enough.

                  In addition to the Teflon coated piston skirts, he is going to use a Fel-pro .040" thick head gasket. The pistons in it now are double half moons, and he plans to use single half moons to compensate for the thicker head gasket. He estimates the compression ratio will be in the area of 9.3 to 1. I told him I wanted everything as original possible.
                  Thanks again for your help.

                  He's going to tear it down first, and then call me to discuss exactly what will be done and to complete a work order.


                  My with a sthe othhouthe 's a single maoper
                  s a sinis shpofpr

                  Comment

                  • Joe L.
                    Beyond Control Poster
                    • February 1, 1988
                    • 43221

                    #10
                    Re: Teflon coated piston skirts

                    Originally posted by Jack Hengehold (33879)
                    Specific to the original question, I'm not sure about 350 pistons, but in the 327 hi-po configuration you don't have a choice of teflon or non-teflon at least in the L2166F (HiPo 11:1) SealedPower/FedMogul/SpeedPro quality brands I prefer. So, I don't think its a question of should I use teflon coated or not. I'd be surprised if your rebuilder had a quality alternative that was non-coated unless he found some pricey NOS units. And as Duke has already noted, I don't think the teflon is at all bad, consequential, or not wanted for any reason...not to mention the other things that are more important to worry about in this endeavor.

                    Jack-------

                    Non Teflon-coated pistons are available for both 327 and 350 cid engines as manufactured by Keith Black/Silvolite. These are available in both hypereutectic cast as well as forged. However, I have no problem, whatsoever, with the use of the Teflon-coated pistons. These are actually used in some PRODUCTION applications. This means they are PRODUCTION-validated which should give one a high degree of confidence in the performance and durability.

                    I recommend hypereutectic cast for all street applications, including those originally using forged pistons. Also, if possible, I recommend the use of flat top style pistons (with 2 or 4 "eyebrows").
                    In Appreciation of John Hinckley

                    Comment

                    • Duke W.
                      Beyond Control Poster
                      • January 1, 1993
                      • 15672

                      #11
                      Re: Teflon coated piston skirts

                      Originally posted by Mike Tower (2682)
                      Thanks Duke, Tom Bob and Al.


                      In addition to the Teflon coated piston skirts, he is going to use a Fel-pro .040" thick head gasket. The pistons in it now are double half moons, and he plans to use single half moons to compensate for the thicker head gasket. He estimates the compression ratio will be in the area of 9.3 to 1. I told him I wanted everything as original possible.
                      Thanks again for your help.

                      He's going to tear it down first, and then call me to discuss exactly what will be done and to complete a work order.

                      The OE head gasket should be .018" and a .040" will drop the OE 9.5-10:1 by several tenths. Compression ratio "estimates" are about as worthwhile as somebody's estimate of which way the stock market will go tomorrow. Piston manufactures list net volume specs and you can assume the head chambers are 62cc, but it's best to measure. If the head and block mating surfaces are level, you can use a shim type gasket, and the thinnest is the .015" Fel-Pro 1094. If there's a couple of thou of warp (not likey) the thinnest composition gasket than will seal with a little warp is .026".

                      Leaving compression on the table will cost in terms of across the range torque power and fuel economy. A few years ago I co-authored an article in The Corvette Restorer on how to manage the CR and it's not a difficult task. If you don't remember it I can send you an e-copy, and you should give it to the engine builder.

                      Tell him to measure deck clearance of all eight before he disassembles the block. If you don't do that never mind anything else I said.

                      Duke

                      Comment

                      • Mike T.
                        Very Frequent User
                        • August 31, 1979
                        • 120

                        #12
                        Re: Teflon coated piston skirts

                        Thanks Duke. I sure would like a copy of your article. Thanks.

                        Comment

                        • Tom P.
                          Extremely Frequent Poster
                          • April 1, 1980
                          • 1815

                          #13
                          Re: Teflon coated piston skirts

                          Originally posted by Duke Williams (22045)
                          The OE head gasket should be .018" and a .040" will drop the OE 9.5-10:1 by several tenths. Compression ratio "estimates" are about as worthwhile as somebody's estimate of which way the stock market will go tomorrow. Piston manufactures list net volume specs and you can assume the head chambers are 62cc, but it's best to measure. If the head and block mating surfaces are level, you can use a shim type gasket, and the thinnest is the .015" Fel-Pro 1094. If there's a couple of thou of warp (not likey) the thinnest composition gasket than will seal with a little warp is .026".

                          Leaving compression on the table will cost in terms of across the range torque power and fuel economy. A few years ago I co-authored an article in The Corvette Restorer on how to manage the CR and it's not a difficult task. If you don't remember it I can send you an e-copy, and you should give it to the engine builder.

                          Tell him to measure deck clearance of all eight before he disassembles the block. If you don't do that never mind anything else I said.

                          Duke

                          Duke,
                          Do you know what issue that was? I have all issues of them back to 79.

                          Comment

                          • Duke W.
                            Beyond Control Poster
                            • January 1, 1993
                            • 15672

                            #14
                            Re: Teflon coated piston skirts

                            ...Fall 2009. I emailed you a pdf of the article and have attached it here for anyone else who is interested. The online CR calculator I use is at:

                            This calculator is designed to show the different Compression Ratios for different sized engines.


                            Duke

                            Compression ratio.pdf

                            Comment

                            • Mike T.
                              Very Frequent User
                              • August 31, 1979
                              • 120

                              #15
                              Re: Teflon coated piston skirts

                              Thanks Duke!!

                              Comment

                              Working...
                              Searching...Please wait.
                              An unexpected error was returned: 'Your submission could not be processed because you have logged in since the previous page was loaded.

                              Please push the back button and reload the previous window.'
                              An unexpected error was returned: 'Your submission could not be processed because the token has expired.

                              Please push the back button and reload the previous window.'
                              An internal error has occurred and the module cannot be displayed.
                              There are no results that meet this criteria.
                              Search Result for "|||"