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  • Cam Plunger spring

    Ok, since I can't find it I will ask.

    Does anyone have the camshaft plunger spring specifics?

    I have 2 springs and both read different pressures. Well, actually 3 springs, one is aftermarket, but that don't count unless the other two are too weak to be functional.
    You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

  • #2
    I read it was 35 in one of the books I have.
    3 ~ Tudor's
    Henry Ford said
    "It's all nuts and bolts"


    Mitch's Auto Service ctr

    Comment


    • #3
      I'm curious how the force is measured, since the amount of spring force is dependent on the spring deflection distance. Do you guys have a spring force test stand?

      Comment


      • Dennis
        Dennis commented
        Editing a comment
        When I worked at a dealer we had one. I was probably the only one that ever used it.

      • DaWizard
        DaWizard commented
        Editing a comment
        Alex, to answer your question, Yes, I have a spring compression test tool/stand, thingy.

        If you are ever in need to use one, call, or drop by, it is close at hand.

    • #4
      It is 35#s. I would measure how far the spring protrudes beyond the timing cover and use that to be you’re 35# compression distance.
      i had a new spring that was 3/8” shorter than the one I took out. It didn’t work, and I reused the old one.

      Comment


      • #5
        Chuck, I'm not so sure that would be the compression distance to use as a guide. I was thinking of doing a bit more digging, like measuring how much distance there is for the cam to block and how much on the cover to mounting surface and using that as my minimum compression distance.

        Hmmm, that typed right coming out of my head but doesn't read right to my eyes...anyway, I think you get what I'm trying to say. See, I am a machinist and have all these kewl measuring tools and I'm retired so I can take the time to use them.
        You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

        Comment


        • #6
          JC- Very nice that you have that tool!
          Would you be willing to plot the curves of some springs so that we can see how much variation there is?

          Comment


          • #7
            I don't see why not, providing you have some specs as a base.
            You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

            Comment


            • Ayyy
              Ayyy commented
              Editing a comment
              I think the spec would be the force/distance, which I don't have.
              The baseline would have to be a NOS spring, which I also don't have.

              If it turns out that the spec distance is the same as the functional operating distance, then that would be meaningful. If the spec distance is different than the functional operating distance, then only the comparison of several plotted springs could tell you if a particular spring is any good. Many samples make better data.

              This is because a single point spec, like having only one force/distance point, cannot define a curve. Even two points cant do it. It takes at least three...and that's pretty chunk data at best.

              JC, ultimately your data could be very helpful here.
              Last edited by Ayyy; 07-13-2018, 07:10 PM.

            • DaWizard
              DaWizard commented
              Editing a comment
              Oh Alex, you almost make it sound like work, and that is a 4 letter word I am allergic to.

          • #8
            Some have placed a flat washer under the cover or used an adjustable bolt to set the tension. It’s better to be on the tight side than the loose or it will float / knock
            3 ~ Tudor's
            Henry Ford said
            "It's all nuts and bolts"


            Mitch's Auto Service ctr

            Comment


            • #9
              Ask the JS committee. Will give 'em something to do that will probably result in chaos..

              Larry
              ____________________
              Good enough.. Isn't.

              Comment


              • DaWizard
                DaWizard commented
                Editing a comment
                Oh Larry, that is diabolical, just like asking them what nut to use to hold on the steering wheel!

            • #10
              Old farts need to make someone smile..
              ____________________
              Good enough.. Isn't.

              Comment


              • #11
                Spring, cam plunger B-6276 fits all 4 cylinder 28-34.
                I have a box of these springs that I have removed from engines, most of them are 1 1/2" long and the wire measures .070".
                I believe these are original Ford springs. Using a bathroom scale on a drill press and pushing them down 1/4" to 1 1/4" which is very close to the length that they would be in the engine, they all showed very close to 15 pounds on the scale.
                I had one spring with the same length and wire size that came out of a Ford combine engine with very low mileage, looks like 500 miles or less.
                This spring and plunger looks new with almost no wear, this spring shows 20 pounds on the scale.
                Based on these measurements I would say that with original spring and plunger, you would have 15 to 20 pounds pushing on the cam.
                I did not have any reproduction springs to test.

                Comment


                • DaWizard
                  DaWizard commented
                  Editing a comment
                  Thank You.

                • Ayyy
                  Ayyy commented
                  Editing a comment
                  L Jones- That's great info!

                  The only fly in the ointment is that bathroom scales tend to vary a bit on accuracy. To complicate that further, 15 pounds out of a full range of 300(?) is only 5% of the full range...this would violate the 20/80 rule-of-thumb which says that a measuring instrument should not be used under 20% or over 80% of its full range due to system hysteresis and non-linearity (most curves look a bit like a very stretched out 'Z', with the bent legs of the Z occurring at 20/80% of the full range). Its just a rule-of-thumb, not absolute.

                  Despite that, your info is a good indication of which way the data would unfold. I can't see your 15 pound value actually changing to 35 pounds during testing with more sophisticated equipment...that's too big of a difference, even with the bath scale inaccuracies.

                  It really makes me wonder where the 35 pound spec comes from.

                  Alex

                • L Jones
                  L Jones commented
                  Editing a comment
                  There may be some truth in your theory about the accuracy of bathroom scales, but our dog weighs between 20 and 25 pounds at the vet, and weighs the same on our bathroom scales, so it is not off more than 1 or 2 pounds.

                • L Jones
                  L Jones commented
                  Editing a comment
                  I pushed the spring down until it read 35 pounds on the scale and it measured 1 inch high.
                  I then pushed the spring all the way down until the coils touched and it measured 80 pounds.
                  You cannot compress the spring in the engine to 1 inch unless you modify the plunger.
                  With original unmodified plunger your spring will be ABOUT 1 1/4 inches long and push about 15 to 20 pounds on the cam.
                  If you modify your spring or plunger to make a large increase in the pressure on the cam, you will increase the speed of wear on the cam and block thrust surfaces.

              • #12
                Well, after doing some measuring, it looks like the spring will only be compressing 3/16". This is after measuring the distance from the cam button to the block surface and subtracting the head thickness of the plunger, so by your calculations I should be in the 10 to 12# range for pressure on the cam.

                Since this engine came with a knock and I suspect from the cam wear that is where it was from, I am going to do more research on the spring load to cam.

                Thanks guys for the help and info.
                You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

                Comment


                • L Jones
                  L Jones commented
                  Editing a comment
                  Another way to figure spring compression is, place the spring and plunger in the timing cover and hold the cover at the front of the engine with the plunger against the cam and a even gap all around the cover and block, then measure the gap between the cover and block.

                • DaWizard
                  DaWizard commented
                  Editing a comment
                  That would work great if it was a new cam, but this one has some wear and that needs to be addressed using that method. By my measuring as I did I already took that into account.

              • #13
                Hey, let us know what you find JC...this is interesting. My truck has an occasional cam knock too (I think).

                Comment


                • #14
                  Well, doing some interweb checking the only number I can find is on the Mac's site and they say "Approximately 35 pounds". Now, I have gone through the Service Bulletins once again and found no help there. So, I guess 35# is about the closest I am going to get without going to Ford and looking up the specs for the spring. So, tomorrow I will do a bit of working around too get the 35# pressure at the cam with the springs I have, be that making a spacer to drive it forward or cutting what is needed from where I can to relieve the tension. I will not accept noise from that place on this engine.

                  BTW, while cleaning up the connecting rods and block I have found the asbestos rope left from pouring babbits and clogged drain holes for bearings. I am surprised that this engine didn't have a lot more noises than a "knock".
                  You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

                  Comment


                  • tbirdtbird
                    tbirdtbird commented
                    Editing a comment
                    Wiz, any follow up on how you made out here??
                    Dave

                • #15
                  Spring pressure at a specified compression height? Has anyone tried researching the original part print microfiche at the Benson Ford Research Center? Real answers trump second hand speculation and questionable reverse engineering.

                  Comment


                  • #16
                    Ok, just a small update. While disassembling the original engine I remembered to measure the distance between the front of the cam and the back of the cover. Now, while this should give be a base for measuring, it did make for an interesting experiment. The distance was .045in so to measure the spring strength at full pressure I still need to measure inside of cover depth and see what the original spring was against the replacement springs.

                    More to come.
                    You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

                    Comment


                    • Dennis
                      Dennis commented
                      Editing a comment
                      Wiz I forgot you posted this awhile back. The distance I measured between my cover and the nose of the camshaft was greater than .o45" I'd say more like between .060 and .125"

                  • #17
                    On a stock ignition system, if you are wondering about the cam moving forward and back, just make a white mark on the pulley for #1 firing, then use a timing light to see if the mark moves when you rev the engine up and down. It should remain in the same place.

                    Comment


                    • #18
                      Tom, not sure how this tells us what the cam is doing.....

                      Comment


                      • #19
                        I knew something was haywire with mine, timing, just by the reading my tachometer showed. It was showing about and increase of 300 - 400 rpm.

                        Comment


                        • #20
                          Thanks Dennis. I think the more important part is what is the distance from the back of the hole to the end of the cam. This is going to dictate the total length of spring and plunger for a spring compression test. Since I believe the hole in the cover is a machined distance and that would give a starting point for the back of the spring. I was measuring the distance between the boss and cam to get a cam face reference to the depth of the machined hole, the actual casting boss before machining won't really matter as well as the distance to the cam from the top of that cast boss. Now, I need to remember to measure the depth of the hole before I reassemble the engine!
                          You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!

                          Comment


                          • #21
                            I think in your earlier postings you mentioned clearance between your cover and the nose of the camshaft from what I interpreted. That is what I got a visual on before I pulled my cover looking up and moving the cam fore and aft. So seeing how much protrusion of the plunger from the front cover was what I based my compressed length on. I'm putting mine back together with the spring set close to 35 lbs. and some assembly lube on the plunger around and on the face.

                            Comment


                            • #22
                              Should someone that knows Skokie drop him a email or a phone call?
                              If any one can answer that question he should.

                              Comment


                              • #23
                                They only use fiber gears because they have the theory that an aluminum gear can contaminate the oil and damage the inserts. Rich also does not think an oil filter is necessary. He does leave it up to the customer to either have one or not. They did not rebuild a long block for me, just a short block. That's not their responsibility with a short block and I don't know what they would say if it were a long block. You are welcome to ask them and post back. I think it's too late in the day to get an answer from them. I will say this, the 22 lbs spring pressure wasn't cutting it and I think there is enough documentation out there to support 35 lbs if you have a means of measuring it.
                                Last edited by Dennis; 08-15-2018, 05:16 PM.

                                Comment


                                • DaWizard
                                  DaWizard commented
                                  Editing a comment
                                  Just so ya know, before I finish with this freshen up, I will have a compression distance for the spring.

                              • #24
                                Originally posted by Dennis View Post
                                They only use fiber gears because they have the theory that an aluminum gear can contaminate the oil and damage the inserts. Rich also does not think an oil filter is necessary.
                                Rich is a good builder but I have to disagree with these 2 items.
                                First, the bearing materials on the shells are now in fact aluminum, so how bad can that metal be? I have had his bearings in my hands, and all modern bearings are made this way. The days of the old fashioned tri-metal bearing with an outer coat of babbitt are over.
                                And, many cars have aluminum timing gears.

                                I am rebuilding a 1947 Stude motor right now and have searched hi and low for old school trimetal for the mains and rods and finally found what I needed. The motor has an oil filter, but it is bypass, so during breakin, you are gonna still have a lot of grit sloshing around. My initial oil changes will be frequent!

                                Second, aluminum does not embed foreign particles such as grit from the rings wearing in and such as well as the old school babbitt, so to me a filter is a must. It certainly cannot hurt.
                                The only reason the aluminum bearings work today is because moderns have had full flow filters now for decades

                                As far as the choice of fiber, we have a guy around here that prefers fiber, also. I have to wonder if these builders are worried that they may not get their centers exactly perfect.....because if not, the fiber will be more forgiving.
                                To me the fiber gear is an anachronism...from an age when aluminum alloying was in its infancy. They sure knew not to make the gear from steel, since steel-on-steel makes a hell of a racket
                                Last edited by tbirdtbird; 08-15-2018, 07:27 PM.

                                Comment


                                • #25
                                  I agree with Dave, I just put a aluminum gear on a engine today that I,m build for myself. I would not use a fiber gear in my engine. When they start coming apart you will have trash in all the oiling holes. The problem is like Dave said, some have trouble hitting the original center line of the mains.

                                  Comment

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