Nylon Timing Gear & chain replacement - NCRS Discussion Boards

Nylon Timing Gear & chain replacement

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  • Duke W.
    Beyond Control Poster
    • January 1, 1993
    • 15662

    #16
    Re: Nylon Timing Gear & chain replacement

    Good choice! From you response in post #3 I figured you went with the three times more expensive aftermarket set.

    I usually recommend the C-3023K for SHP rebuilds as the additional noise will likely not be noticeable with the normal SHP engine cacophony. The C-3001K roller chain is also perfectly acceptable and might be my recommendation for a base engine car that the owner drives very conservatively, and is more interested in "luxury" behavior than "performance".

    At this point, either will likely outlive most of us.

    Duke

    Comment

    • Joe R.
      Extremely Frequent Poster
      • July 31, 1976
      • 4550

      #17
      Re: Nylon Timing Gear & chain replacement

      Chevrolet does sell a set existing of a single roller chain, crankshaft sprocket and camshaft sprocket. It's part number is 12371043. It's for the 1987 and newer engines with the roller lifter camshaft except LT1, LT 4 and LS series. The extreme duty Kit p/n 12370835 is for LT 1 and LT 4 engines and is a single roller design.
      For ZZ design and older engines the roller timing chain p/n 14088783 can be used with 14088784 and 12552129 sprockets for a nice single roller set.
      Genuine GM!!!!

      JR

      Comment

      • Domenic T.
        Expired
        • January 29, 2010
        • 2452

        #18
        Re: Nylon Timing Gear & chain replacement

        This is well known, but I'll say it. Back in 70 & 71 when I twisted a wrench for a Chevy dealer we changed the timing gears on a daily basis. They usually made it about 75k or so. When I asked the service rep from GM he said the plastic was quieter than the all metal!! Yes I said, but when the valves and Pistons collide the noise is horrible. I actually saw the timing covers worn thru from the chain rubbing them and oil everywhere. They used to jump a tooth and the engine would either idle VERY high or not at all depending which way it jumped the tooth. Thank God for the double roller.

        Dom

        Comment

        • Duke W.
          Beyond Control Poster
          • January 1, 1993
          • 15662

          #19
          Re: Nylon Timing Gear & chain replacement

          I think the truck double-row roller chain has been around, essentially unchanged, since the 1950s, and it costs about the same as the passenger car Morse chain in the various forms, but most guys don't know anything about it.The Chevrolet Power Manuals from the seventies recommended use of either the early, wide Morse chain that was still available then or the truck roller chain. The switch to the nylon sprocket was accompanied by a slightly narrower chain, and current replacments are still the narrower chain, but with a cast iron spocket.

          Duke

          Comment

          • Joe L.
            Beyond Control Poster
            • February 1, 1988
            • 43213

            #20
            Re: Nylon Timing Gear & chain replacement

            Originally posted by Duke Williams (22045)

            The switch to the nylon sprocket was accompanied by a slightly narrower chain, and current replacments are still the narrower chain, but with a cast iron spocket.

            Duke

            Duke-------


            1955-66 small block used the wider Morse timing set. 1967+ used the narrower. However, 1966 used the wider with a nylon-toothed camshaft sprocket. I have an NOS example of that sprocket, GM #3865964.
            In Appreciation of John Hinckley

            Comment

            • Joe L.
              Beyond Control Poster
              • February 1, 1988
              • 43213

              #21
              Re: Nylon Timing Gear & chain replacement

              Originally posted by Domenic Tallarita (51287)
              This is well known, but I'll say it. Back in 70 & 71 when I twisted a wrench for a Chevy dealer we changed the timing gears on a daily basis. They usually made it about 75k or so. When I asked the service rep from GM he said the plastic was quieter than the all metal!! Yes I said, but when the valves and Pistons collide the noise is horrible. I actually saw the timing covers worn thru from the chain rubbing them and oil everywhere. They used to jump a tooth and the engine would either idle VERY high or not at all depending which way it jumped the tooth. Thank God for the double roller.

              Dom

              Dom------



              Quiet operation was the entire reason for the nylon-toothed camshaft sprocket, the powder-metal crankshaft sprocket, and the Morse-type chain.
              In Appreciation of John Hinckley

              Comment

              • Joe L.
                Beyond Control Poster
                • February 1, 1988
                • 43213

                #22
                Re: Nylon Timing Gear & chain replacement

                Here are some photos of the 1966-0nly GM #3865964 and the 1967+ sprocket.


                DSCN1252.jpgDSCN1249.jpg
                In Appreciation of John Hinckley

                Comment

                • Joe L.
                  Beyond Control Poster
                  • February 1, 1988
                  • 43213

                  #23
                  Re: Nylon Timing Gear & chain replacement

                  Originally posted by Duke Williams (22045)
                  You can't go wrong with either a Cloyes/NAPA silent chain (C-3001K/203001) - the second design which is slightly narrower than the early silent chain - or the truck roller chain (Cloyes C-3023K/NAPA 103023). The Cloyes Web site says sprockets are steel, but I believe that the cam sprockets are cast iron, which is fine. Cast iron is very tough and has excellent wear characteristics. The steel crank sprocket is hardened steel for both strength and good wear characteristics, but given that the cam sprocket has double the number of teeth, unit loading is half the crank sprocket, so steel offers no advantage and would cost more.

                  They are both manufactured by Cloyes, but NAPA sells them under their own brand too, so buy on price (20-25 bucks for the sets) and convenience.

                  The truck roller chain can also be purchased with three indexing keyways on the crank sprocket to install the cam at as-manufactured indexing or advanced or retarded four degreesn - C-3023X/103023X.

                  Cloyes' "Tru-Roller" is just marketing BS. A roller chain is a roller chain - the roller engages the sprocket and rolls around the pin - just like a motorcycle chain.

                  The so-called "Tru-roller" has larger rollers - .250" versus .200" for the OE replacement truck chain set. The larger rollers will take greater shock loading, so if you regularly do 5000 rev clutch drops and power shifts, it may offer some durability benefit, but not too many do that, and it's common for the larger rollers to interfere with the timing chain cover, which requires rework to gain sufficient clearance.

                  It doesn't make sense to buy the aftermarket set which provides absolutely no benefit for normal road driving at over three times the cost of the OE replacement sets.

                  Duke

                  Duke-------


                  Are the timing sets you mentioned adequate? Absolutely YES. In fact, stock GM timing sets are adequate, too. Also, "no-name" timing sets you find at swap meets for about 10 bucks are likely adequate, too. Is the Cloyes Tru Roller necessary for street operation? Definitely not.

                  However, the notion that the 20-30 buck timing sets are about the same as the Tru Roller in overall quality is off-base. The idea that Cloyes makes the 20-30 buck timing sets about the same as the Tru Roller and relies on suckers to sell the Tru Roller is just not the way it is in my opinion. In the vast majority of cases, one gets what one pays for. The Cloyes Tru Roller costs more than 3 times what the OEM replacement sets sell for and the reason is that a lot more manufacturing cost and quality goes into it. Does one need this for street operation? No. But, I like to have it.

                  Also, I've never seen a Cloyes advertisement pushing the Tru Roller so I don't see where marketing hype figures into this, at all. The Tru Roller series has been around for a LOT of years. I first used one more than 30 years ago and they were around much before that. So, they're tried-and-true and many folks, including me, swear by them. Parts like this don't last this long in the world of automotive parts if they're about the same as much less expensive parts.
                  In Appreciation of John Hinckley

                  Comment

                  • Joe L.
                    Beyond Control Poster
                    • February 1, 1988
                    • 43213

                    #24
                    Re: Nylon Timing Gear & chain replacement

                    Originally posted by Joe Ray (1011)
                    Chevrolet does sell a set existing of a single roller chain, crankshaft sprocket and camshaft sprocket. It's part number is 12371043. It's for the 1987 and newer engines with the roller lifter camshaft except LT1, LT 4 and LS series. The extreme duty Kit p/n 12370835 is for LT 1 and LT 4 engines and is a single roller design.
                    For ZZ design and older engines the roller timing chain p/n 14088783 can be used with 14088784 and 12552129 sprockets for a nice single roller set.
                    Genuine GM!!!!

                    JR

                    JR------


                    All ZZ-series engines are roller cam and this means the individual timing set components you mentioned are for roller cam applications. They might work for flat tappet applications, though. In addition, though, the 3 individual components you mentioned carry a combined GM list price of about $195. One should be able to buy them for about $150 but that's still more than a Cloyes Tru Roller set.

                    By the way, timing sets for GM roller cam application are usually single roller. That's because there is not enough clearance for a double roller with the thrust plate used with factory roller cam applications. Aftermarket roller cam set-ups can use a double roller since these generally use a thrust button rather than a thrust plate.
                    In Appreciation of John Hinckley

                    Comment

                    • Timothy B.
                      Extremely Frequent Poster
                      • April 30, 1983
                      • 5183

                      #25
                      Re: Nylon Timing Gear & chain replacement

                      Originally posted by Joe Lucia (12484)
                      Duke-------


                      Are the timing sets you mentioned adequate? Absolutely YES. In fact, stock GM timing sets are adequate, too. Also, "no-name" timing sets you find at swap meets for about 10 bucks are likely adequate, too. Is the Cloyes Tru Roller necessary for street operation? Definitely not.

                      However, the notion that the 20-30 buck timing sets are about the same as the Tru Roller in overall quality is off-base. The idea that Cloyes makes the 20-30 buck timing sets about the same as the Tru Roller and relies on suckers to sell the Tru Roller is just not the way it is in my opinion. In the vast majority of cases, one gets what one pays for. The Cloyes Tru Roller costs more than 3 times what the OEM replacement sets sell for and the reason is that a lot more manufacturing cost and quality goes into it. Does one need this for street operation? No. But, I like to have it.

                      Also, I've never seen a Cloyes advertisement pushing the Tru Roller so I don't see where marketing hype figures into this, at all. The Tru Roller series has been around for a LOT of years. I first used one more than 30 years ago and they were around much before that. So, they're tried-and-true and many folks, including me, swear by them. Parts like this don't last this long in the world of automotive parts if they're about the same as much less expensive parts.

                      Joe,

                      If you use the tru roller Cloyes chain is there interference with the timing cover? How about the double truck chain and interference, I have never experienced any problems just using the iron camshaft gear and stock chain.

                      Comment

                      • William F.
                        Extremely Frequent Poster
                        • June 9, 2009
                        • 1363

                        #26
                        Re: Nylon Timing Gear & chain replacement

                        duke, et al
                        Guess I'm a slow study but I'm confused, Seems one place Duke's saying the "Tru Roller" is bs and all hype, another seems like it's recommended. Help me out. Please give PN's and description for timing best timing chains that wouldn't interfere with timing cover chains for '67 L79 and L36. Are the Cloyes/NAPA chains mentioned as being good choices "Tru Roller" designs or just good quality chains with cast iron and steel gears?
                        Thanks

                        Comment

                        • Duke W.
                          Beyond Control Poster
                          • January 1, 1993
                          • 15662

                          #27
                          Re: Nylon Timing Gear & chain replacement

                          Originally posted by Joe Lucia (12484)
                          Duke-------


                          1955-66 small block used the wider Morse timing set. 1967+ used the narrower. However, 1966 used the wider with a nylon-toothed camshaft sprocket. I have an NOS example of that sprocket, GM #3865964.
                          ...didn't know that, but a local chapter member changed the timing set in his '65 L-79 a couple of years ago, and to my surprise it had a nylon tooth cam sprocket. It was a low mileage car -well under 100K - that had been stored for years, so I doubt if the timing set had been changed, but maybe it had, and I don't know if it was wide or narrow, but could the nylon cam sprocket have been a running change during the '65 MY?

                          I heard of those nylon sprockets shedding teeth as early as the late sixties, but I think those cars were run hard. The nylon teeth were definitely weak when it comes to drag racing starts and power shifting which places big shock loads on the set, and then over the years thermal cycles weaken the material.

                          Duke

                          Comment

                          • Duke W.
                            Beyond Control Poster
                            • January 1, 1993
                            • 15662

                            #28
                            Re: Nylon Timing Gear & chain replacement

                            Originally posted by William Ford (50517)
                            duke, et al
                            Guess I'm a slow study but I'm confused, Seems one place Duke's saying the "Tru Roller" is bs and all hype, another seems like it's recommended. Help me out. Please give PN's and description for timing best timing chains that wouldn't interfere with timing cover chains for '67 L79 and L36. Are the Cloyes/NAPA chains mentioned as being good choices "Tru Roller" designs or just good quality chains with cast iron and steel gears?
                            Thanks
                            The term "True-Roller" is marketing hype. It implies that there is some functional/operational difference between the Cloyes expensive aftermarket set compared to the OE replacement truck roller chain. There is not as I explained in post #14 where I also recommended inexpensive OE-replacement sets and gave part numbers. It's amazing how inexpensive these high quality, durable sets are considering the dozens of precisely machined parts that make them up, but they have been manufactured in high volume for decades, which brought down manufacturing cost to unbelievably low levels.

                            The only difference I can see between the two is the larger rollers in the aftermarket chain, (which can cause interference with the timing cover in some cases), and I doubt if there is any difference in material specs, heat treatment, or manufacturing tolerances.

                            I've known Chevy owners over the years whose engines went 150-250K miles without every being opened up with either the wide or narrow Morse Chain with cast iron cam sprockets or the truck roller chain. All are very durable.

                            Guys obsess way too much over this. (They should fret more about SB conn. rods and BB valve springs.) The only timing chain sets that were ever problematic are the those with nylon tooth cam sprockets, and they are no longer manufactured by any source that I know off, and even if they were one would be a fool to buy and install a nylon tooth cam sprocket timing set. NOS nylon cam sprocket sets are useful for display purposes only!

                            All the other configurations should last the life of the engine, but the truck roller chain is likely the most durable, and it's the one I recommend for most rebuilds, especially SHP engines. If one has a base engine with AC and other luxury options, like an auto trans, a quiet exhaust system and doesn't drive the car hard I might recommend the Morse chain with a cast iron cam sprocket because it is quieter, but I doubt if the difference can be discerned from the driver's seat. Vintage Corvettes have a good deal of NVH compared to most contemporary cars of the era, but most guys find vintage Corvette NVH pleasant and part of the car's charm, especially engine/exhaust sound, which will likely cover up any difference in noise between a Morse chain and roller chain.

                            There are guys who claim they can tell which OE mechanical lifter cam is installed by listening to the car idle with the hood open, which I dispute. So far no one that I am aware of has ever claimed they can tell the difference between a Morse and a roller chain.

                            Duke
                            Last edited by Duke W.; October 4, 2015, 10:57 AM.

                            Comment

                            • Joe L.
                              Beyond Control Poster
                              • February 1, 1988
                              • 43213

                              #29
                              Re: Nylon Timing Gear & chain replacement

                              Originally posted by Duke Williams (22045)

                              I don't know if it was wide or narrow, but could the nylon cam sprocket have been a running change during the '65 MY?


                              Duke
                              Duke------


                              It's very possible that the actual change to the wide nylon-tooth cam sprocket occurred during the 1965 model year. In fact, the part number implies that it could have been released during the 1965 model year, although, if so, I would expect it was late in the model year.
                              In Appreciation of John Hinckley

                              Comment

                              • Joe L.
                                Beyond Control Poster
                                • February 1, 1988
                                • 43213

                                #30
                                Re: Nylon Timing Gear & chain replacement

                                Originally posted by Timothy Barbieri (6542)
                                Joe,

                                If you use the tru roller Cloyes chain is there interference with the timing cover? How about the double truck chain and interference, I have never experienced any problems just using the iron camshaft gear and stock chain.
                                Tim------


                                I have never had a problem with interference with the timing cover when using the Cloyes Tru Roller and I've never heard of anyone having such a problem. I've installed quite a few of these. However, while I've never had the problem, I've heard of a few folks that had a very slight interference with the block. Very minor relieving with a Dremel tool solved the problem. Since I've only heard of it a few times, I expect the root cause is excessive core shift in those blocks.
                                In Appreciation of John Hinckley

                                Comment

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