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Moss cam sprocket

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  • Moss cam sprocket

    i have ordered a new timing chain and cam sprocket from Moss.
    i wondered if anyone has used this sprocket. the reason i ask...
    a number of people like to advance their cam 4* for lower end power and i believe it helps the engine run cooler. Moss shows two markings on their sprocket. the "B" mark is for stock cams and the "A" mark is to advance the cam 4*. All sounded good until it said that is 4* on the cam but 8* at the crank.
    is that too much for a stock cam?

    Thanks
    oh car is a 76 year all stock.

  • #2
    I don't have the Moss sprocket; I have an adjustable one, but I did advance the cam timing 4 crankshaft degrees the last time I had the opportunity....that was with the stock cam Stanpart # 311399.
    I think it worked out well.

    And BTW, I did answer your inquiry about the cylinder hone.
    Last edited by poolboy; 11-08-2018, 06:22 PM.
    Driving a 1973 TR6
    Doing ZS carb repairs
    email kencorsaw"at"aol.com

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    • #3
      Ken
      Thanks for the info. i have not seen the info on the hone but maybe i just can't find it on the site now. nothing shows up in messages..... oohhhhh, maybe i need to go back in to my profile and change something there with the new site. i will check it out. i was not on for a long while. i was working on another car. So thanks for the info.

      anyway am guessing this setup will advance the cam timing too far. was hoping i would get lucky.

      Comment


      • #4
        I didn't know there was such a thing as a "visitors message" until I got notification of one you sent me...anyway here's a link:
        http://www.6-pack.org/vb5/member/201...from-drone-dog
        Driving a 1973 TR6
        Doing ZS carb repairs
        email kencorsaw"at"aol.com

        Comment


        • poolboy
          poolboy commented
          Editing a comment
          BTW, don't feel like you have to use those A and B markings on the sprocket.
          Time your cam 'straight up' the usual way, then referring to the damper degree marks turn the crankshaft back CCW the number of degrees you want to advance the cam, (without turning the cam, naturally) then attach the chain and cam sprocket as close as you can to your desired advance setting...You may not get exactly the 4* advance with a non adjustable sprocket, but you'll be able get some advance

      • #5
        Ken
        thanks for the tip. i was just thanking about that. but i was thinking about retarding the gear against the "A" mark. going to count the teeth tomorrow and do some math and see if i can figure something out. then play with it when i get my parts. sounds like fun.

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        • #6
          Ken
          i also want to check out flipping the gear over. Think I can pick up smaller increments of degrees there.

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          • #7
            I've seen some post on this forum in the past,TL, by guys who used the other set of holes and/or the "next tooth" on the cam sprocket and I don't remember exactly what the were able to accomplish, but I think it was 2 or 3 degrees advance...something like that.
            Driving a 1973 TR6
            Doing ZS carb repairs
            email kencorsaw"at"aol.com

            Comment


            • poolboy
              poolboy commented
              Editing a comment
              Keep this in mind.
              If you need to advance the cam (valve) timing after you have the cam timed straight up, then you can either keep the cam stationary and rotate the crank CCW ...or keep the crank stationary and rotate the cam CW...
              I suppose there are situations where a person might need to do a combination in order to accomplish their cam timing goal...whatever just be aware of what does what.
              Last edited by poolboy; 11-09-2018, 12:25 AM.

          • #8
            Well i played around with this today. nothing on the actual engine as i did not have the rod bearings back in yet. i didn't want to move the crank.

            but i laid the gears on a piece of carboard and also did some math. it is true you can pick up 4* of advance by flipping the cam gear over. But the problem there is the offset in the sprocket then has it set so far away from the engine, i don't think you could ever get the crank gear to line up.

            the crank gear also is offset so flipping it over would also make alignment tough. i have seen crank gears with multiple keyways cut in to them and that would be the most logical answer.

            i did get the new cam gear from Moss this afternoon but it does not have the marks on it they said it would. looking closely at my old gear there are marks for the dead straight on and the 8* (crank) advance. (basically a half tooth) kind of sucks the new gear is not what they said, but i can figure where the marks would be by lining up with my old gear.

            looking at it from the math side here is what i came up with. there are 42 teeth on the cam sprocket and 21 on the crank. so they both work out the same degree as far as the crank is concerned. meaning 1 tooth on the cam is about 8.57* but when you double that for the crank measurment, it comes out to 17.142* which is the same as one tooth on the crank. So i don't think i can retard one against advancing another and gain anything. now this is purely on the math side. may turn out a little different in reality.

            but for now the only advance i think i can get is maybe the play in the bolts vs the holes in the cam gear. at best that would be about 2*. of course with a new chain, i may not be able to do that.

            guess that is why someone makes an adjustable cam sprocket...

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            • #9
              i have another question to throw in the mix here. if i shave the head to 3.475 (it is now 3.55) to gain some compression do i retard the valve timing and how much?

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              • #10
                No, that's no reason to retard the the cam/valve timing
                Driving a 1973 TR6
                Doing ZS carb repairs
                email kencorsaw"at"aol.com

                Comment


                • #11
                  sorry that was written poorly. from what i read, shaving the head will retard the timing. i was wondering about trying to advance it to offset that. ANd to what degree shaving the head about .075 would change the cam timing.

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                  • #12
                    Originally posted by Drone Dog View Post
                    sorry that was written poorly. from what i read, shaving the head will retard the timing. i was wondering about trying to advance it to offset that. ANd to what degree shaving the head about .075 would change the cam timing.
                    I don't believe that shaving the head will retard the cam timing. Possibly what you read was shaving the head, or raising the CR, it is sometimes necessary to retard the ignition timing ( to lessen the chance of detonation).

                    Dick

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                    • #13
                      Just FYI, my sprocket came without any marks so a bit of bad info from Moss.

                      Comment

                      Moss cam sprocket

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