Post Conversion - Crank Rotation Tight

Discussion in 'Half VW' started by Tuneturkey, May 31, 2019.

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  1. Jun 4, 2019 #21

    Hot Wings

    Hot Wings

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    Didn't catch that this was a full case 1/2 VW. Doesn't make much difference regarding the tightness.

    If you are using a stock distributor with points just grind off the #1 and #3 lobes. #3 is retarded on most VW distributors. This means that the #4 distributor lobe now fires at TDC (or however many degrees advance you use) #4. This is 90 crank degrees later than the original #1 TDC. Mark this new TDC using the normal procedures to find TDC and go from there.

    If you have already ground off #2 and #4 lobes and use the original #1 lobe for #4 cylinder, the engine will run but the #2 cylinder will have slightly retarded timing. If you started with an '050' distributor you can use any pair of opposite lobes you choose. There is no retard on this distributor. TDC #1 is marked on the distributor with a little stamped spot on the rim under the cap. When the rotor is pointing at that stamp the lobe under the points is #1.
     
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  2. Jun 4, 2019 #22

    Tuneturkey

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    Hot Wings,
    The distributor is an 009 Probably Empi or some such, and there is no truly definitive stamping on the rim. There is what appears to be a circular depression on the lip that looks more like a scratch then a stamping, so I am not sure where #1 TDC is, or the orientation of the rotor or cap.
    1. Can I do the orientation based on the physical position of the #4 piston. With plug out I can feel the air coming out of the plug hole on #4 which should be TDC for #4. Can't I just rotate the distrib. body until a lobe on the shaft opens the points. The 4 lobes on the shaft are symmetrical so why does it matter which lobe is used, so long as the ignition wire is connected corresponding with the position of the rotor. With that done, won't #2 cyclinder rotor position be 180 deg away from #4 rotor position? or
    2. This is a type 1 engine. Should I pull the distrib. and rotate the crank until the slot in the distrib. drive is 90 deg to the case split with offset lobe at the top ( me facing the pulley). Then reinsert the distrib. With that done, the rotor should be pointing to #1 TDC. Can I then just rotate the distr. body until the points open? That would identify the #1 position. #4 position on the cap would be 90 deg clockwise, and #2 would be 180 deg from #4.

    Seems overly complicated!! I am assuming that once #1 TDC is determined, and the distrib. rotator locked down, it doesn't matter how the distr. body is orientated so long as the points open at the #1 TDC position. with that done, Firing point for #2 and #4 are automatically set.

    Comments please!
     
  3. Jun 4, 2019 #23

    Hot Wings

    Hot Wings

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    How are you going to do this if there is no cylinder/head on #1?
    Here is a pic of the VW distributor showing the #1 TDC indicator.
    notch.jpg
    One other variable I forgot: One of the biggest timing problems I ran into with customer rebuilds was not getting the distributor drive gear properly indexed with the crank gear. Get that wrong and trying to match the photo for timing just doesn't work. In the end all that matters is when the spark occurs. Where the rotor points relative to the case parting line is pretty much irrelevant for a modified 009 distributor in a 2 cyl engine.

    The only reason to be concerned with the #1 TDC distributor mark is to be able to identify the #3 lobe so it, and #1, are the ones that get ground off. Once that is done stick the distributor in, set the engine to TDC on #2, or #4,** and then twist the distributor until the points just open. Run the plug wires to the appropriate cylinder and it should be good enough to start, with a timing light hooked up.

    ** This TDC mark is one that you will have to make.
     
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  4. Jun 28, 2019 #24

    Tuneturkey

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    Pops, etal!
    New Day, new DATA:
    Disassembled the engine. Tightness decreased as small outer bolts were loosend , and more so as main 6 bolts were loosened. Tightness reduced to where short wood prop could be turned with one finger. I continued to open it up and found:
    1. All dowels were in place in the main bushings.
    2. Cam bearings show rubbbing ( scratches) on the left case, opposite side of bearing from the crank. See pic IMG_3279, opposite half of cam bearings showed no wear, not scratches. On left case, cam bearing closer to the prop showed more scratches then the back bearing.

    My first conclusion at this point is that the center line of the crank is closer to the centerline of the cam then original, whereas the new, std cam gear (01) gets wedged in, pushing out on the front bearing, and to a lesser degree on the back bearing. I still plan to close up the case with only the Crank in place and check for fit, then repeat the process with only the cam in place.

    Your comments on the above are welcome. If my conclusion proves accurate, my next question will be how much undersize do I get, -1, -2, -3? I really don't have any clue as to the reduction in diameter represented by the numbers, mm or what?

    As a side issue, I have inserted cylinder shims to decrease the compression to about 7.5 in favor of using std. prem. auto fuel. Recommendation have been to leave off the shims to keep the compression ration high around 8.0, and hp as high as possible. This is a good time to make the change, since it is all apart. comments please.

    Johnc
     

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  5. Jun 28, 2019 #25

    Tuneturkey

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    HOLD UP:
    I made a mistake (my bad)

    In looking at the pics, I had my directions wrong. Noting the cover plate over the unused cyl , the excess scraping is on the fly wheel end of the case, not on the prop end. That blows my conclusion out the window.
     
  6. Jun 28, 2019 #26

    Hot Wings

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    Now you know why I don't gamble. I lost this one.

    That looks like more than 'scratches' on the center cam bearing and the sealant film on the center main bearing saddle looks kind of thick.

    My new best guess, not a wager, is a warped case. Before you bolt it back together with either the cam or crank, just bolt the 2 case halves together and only torque the center main bolts to 10 ft lbs. Take a look at the center main bearing saddle with a light from behind. If you see any gap - new case time.
    If it passes this test I'd try the cam only in a fully torqued case to see if it turns with nothing more than a screwdriver and wrist torque. From the photo of the center cam bearing I'd give 2 to 1 odds that the cam bore needs a quick cleanup.
     
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  7. Jun 29, 2019 #27

    Tuneturkey

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    OK sounds good! What constitutes a "quick cleanup"? Align bore CAM bearing saddles? Please explain. visualizing the case assembled, right side up, if the two cam saddles where mis-aligned, the excess wear or scratching would not be on the same side of the bearings as seen in the pic, but on opposite sides. When I assembled the case, I used an alternating pattern at each torque level. Could the torqueing process induce a few thousands offset in the cam saddle alignment?
    A little more history that maybe relevant. The Crank came from a different engine. The original cam was corroded beyond repair, and had excessive wear on one of the lobes. It was a flat face cam working with a std depth 26mm pump. Bought a dished cam and deep, 26mm pump to match. case and pump have been plugged for full flow oil. Cam gear and crank gear mesh well with the cam centered on its bearings, but tightly.
    Lastly, (confessing all my sins), when I was installing the prop hub, it was not hot enough and refused to budge when about 50% on the crank. Had to have it pressed on at a local shop. Don't now exactly how they did it, but no evidence of damage to the crank. Also, local shop messed up the counter weight install and could not dynamic balance, so I shipped to Scott at Hummel engine who completed the job.
    Needless to say, my original cost estimate of the rebuild is long past acceptable! Too much more and I will be approaching a new engine from Hummel!
    Please stay with me on this!
    if anybody else has comments please chime in!!
    Johnc
     
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  8. Jun 29, 2019 #28

    Pops

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    I agree with Hot Wings again and like Hot Wings, I don't gamble :)

    Remember the lobe on the dist for #3 is not the same as the others, it's a slight amount to the side to retard the timing on #3 a couple of degrees, so its important to grind the correct lobes off the shaft. One of the lobes you grind off needs to be #3.
     
  9. Jun 29, 2019 #29

    TFF

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    You are going to have to do a runout check of the cam and crank. When the crank flange was pressed on, one should have been done then. Assemble the case with the bearings, then measuring the bearings and then the journals. Crank seems ok, but it still was a bearing problem. The guesses were close enough.

    I had a friend buy a new cam for his Mercedes and cam stands. The new cam stands were not straight. They would lock the cam. The old ones were ok, but he was doing what was recommended by putting in new. Had to use the old. So anything can be off.

    If the cam gears are too tight, you will need different ones. I guess if you were really desperate, you could build something to spin them meshed and add lapping compound until you grind out the clearance. The problem with that is it might open up other clearances you don’t want to with the teeth.
     
  10. Jun 29, 2019 #30

    Tuneturkey

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    Thanks TFF:
    "runout check of cam and crank" - please explain!
    "assemble the case with bearings, then measure the bearings and then journals" If the case is assembled, how do I measure the bearings and journals? If I am going to measure with the case open, why bolt up the thing first? No offense intended.
    Please clarify! I need to find out what is wrong, so I'll do any testing suggested. Pops has already suggested the case be bolted up with only crank first, then only cam to check for tight fit. How can I coordinate your suggestion with Pops?
    Thanks,
    Johnc
     
  11. Jun 29, 2019 #31

    TFF

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    There are tools that can measure the bore directly and some that can transfer to calipers. Tons of videos on YouTube

     
  12. Jun 29, 2019 #32

    TFF

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    You have to adapt but most of this stuff is pretty standard. You will want to check the runout if the prop flange
     
  13. Jun 29, 2019 #33

    Tuneturkey

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    The cam gear and crank gear are not meshing properly. the main point of contact appears to be the ends of the crank gear with the cam gear. Also, the spots of wear start out very small and increase in size after 90 deg od rotation, then get small again until disappearing at about 180 deg. of rotation. IMHO that means that the centerline of the cam is not parallel to the centerline of the Crank (the spot contact instead of full tooth), and the cam gear is not 90 deg to the centerline of the cam. That doesn't make me happy!!
    Cam gear wear spots.jpg
     
  14. Jun 29, 2019 #34

    Hot Wings

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    If the shop pressed the prop flange on the easy way, rather then supporting it under the first rod throw, they could have bent the crank. The fact that it seems to turn freely is a good sign. But you should still put the crank, and cam, in some "V" blocks and check it's 'trueness' with a dial indicator.

    As for the cam bore there is a special VW boring bar that is placed in the cam bore that cuts only the center bearing saddle. Most of the time it's the center saddle only that gets out of alignment. This happens when the center main bearing saddle has been working and the case is 'spread'.* When the main bearings are line bored with a fully torqued case the main bore is straight, but often the fact that the case is spread is missed. The result is that the crank turns freely, if the case is torqued to the same values and pattern. The cam bore is still ovaled and pinches the cam. Cutting the center cam bore saddle 'fixes' this.

    The basic problem may still remain - a warped case. My earlier advice about torquing a bare case using only the center main bearing studs is a quick way to check for a warped case, but not the best or fool proof. It's good enough for me to use on a ground bound vehicle, and offer a warranty. The reason that it may not be suitable for aircraft is that a slightly warped case will test as good using this method but because it isn't every time the case is bolted together and torqued the dimensions will be just a little bit different.

    * I'd often find center main bearing stud nuts only finger tight, or even slightly backed off, during tear down. These cases went directly to the iron bin. Do not use the case "seal nuts" with the seal side next to the block/washer. It's one of the dumbest things VW ever did.
     
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  15. Jun 29, 2019 #35

    Tuneturkey

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    Thanks for the educational materials.
    let me add to the database with something i just found.
    With the case halves side by side, I cleanded off all the excess sealant on the machined surface. At that time I noticed the ware dots I reported in the post above. In order to see the two gears meshed together, I lubed the main bearings and put the crank back in place, working the bearings until all three were set on the dowels. That done I rotated the crank which spun freely. Lubed the cam bearings, rotated the cam to align the dots and set the camm on its bearing. I slipped rite in, and the two rotate freely together, unlike the previous assembly. I spun the crank CW and CCW and the cam stayed on its bearings. Being a bit encouraged, I went ahead and placed the 2nd half of the case, and tightened the 6 main bolts incrementally to 10 ft-lbs.
    The crank continued to turn freely, but not quite as freely as with the open case. Actually, a strong pull on the prop hub will spin it more then one rotation, although the perpherial small bolts are not installed, and nothing is up to full torque. Didn't do that before.
    I did a video turning the wood prop attached to the hub, but it is 30mb so can't be attached. Do you have your on website, or a dropbox acc't so I can send it to you?
    Hopefully, that was the problem all along. I am going to add more small bolts and track rotation as I do so back up to full torque.
    I am beginning to think that y'all were right to begin with.
     
  16. Jun 29, 2019 #36

    proppastie

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  17. Jun 29, 2019 #37

    BBerson

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    I think Hoover said there was 4 or more different cam gear sizes. Need the correct one.
    I mentioned plastiguage in first post, I think.
     
  18. Jun 30, 2019 #38

    Tuneturkey

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    Yes, I am aware of plastigauge, and how to use it.
    At this point, I think that one of the main bearings was not fully seated, although they all appeared to be. Or, in closing up the case, I lifted up the crank from the prop hub and the front bearing rotated slightly and off of the dowel. At this point, with all three bearing well seated, the crank and cam rotate freely. Problem is how freely should they rotate. I have no experience on making that judgement. They rotate much more freely then before, even with full torque on the 6 main bolts. if the case is truly warped, will torquing the other bolts to spec. tighten it up again?
     
  19. Jun 30, 2019 #39

    TFF

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    I would say a crank and cam by themselves should spin just with your finger, oiled bearings of course. There is the weight of the components to overcome, but if you spun it hard, I bet it should turn at least 1/2 turn carrying inertia. They should glide
     
  20. Jun 30, 2019 #40

    Tuneturkey

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    Great! I have a length of wood ( 1"x4"x 24") attached to the prop hub. With the main 6 case bolts torques to 25# I can spin the crank with one finger. A hard spin will carry on 1+ more revolutions.
    going back to the discussion of warped cases, My concern is that torqueing up the smaller bolts all around the case will distort the case, and bearings. Should I follow some special torquing sequence to prevent that, i.e. Torque the main 6 bolts first to full 25#, then bring the outer bolts up 5# per round alternating bolts on opposite sides of the case, until all are up to spec? or what do you recommend.

    Looking closely at the initial tightness, I think that the front (Prop end) main bearing lifted during closing the case, and the dowel didn't go all the way down. Now, a close look at the meshing of the two gears, they appear to be meshing evenly across the teeth, with no lifting of the cam from the bearings. I can still detect a bit of ex-centricity in the cam gear as the depth of mesh varies maybe a couple of mm (my guesstimate) , from teeth bottoming out a couple of mm clearance. The cam gear tracks the crank gear with no wooble.
    A close look at the cam bearings now shows even marking across the rear cam bearing. Noteworthty however, the rear cam bearing had some white lithium grease on it that turned light grey, whereas the front bearing stayed white. could be just residual from the initial assembly, but also maybe indication that I should plastigauge the bearing.

    Note: at assembly of the connecting rods, I used lithium grease on the bearings, and also on the cam bearings which may be contributing to the tightness (higher viscosity when cold). Probably should have just used engine oil.
    on initial assembly I used typical aircraft permatex sealant on the case half faces which is thick and hard to spread evenly. Is there a better product?
    Thanks for staying with me on all of this!
    Your help, as well as comments from others is much appreciated! Hooray for Forums!!!
    Johnc
     
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