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oil pump drive angle not quite 47-49 degrees

Discussion in '"Stock" Alpine' started by mightyohm, May 28, 2019.

  1. mightyohm

    mightyohm Gold Level Sponsor

    The cam and pump are matched, 11 teeth each. That should be correct for the 1725. I have a few 1725 oil pumps and cams and they all have the same number of teeth so I'm pretty confident I have a good combination. Also, the motor was running before I tore it down to fix a ring issue and the cam gear looks fine.
     
  2. mightyohm

    mightyohm Gold Level Sponsor

    This is one of the "new old stock" blocks from Sunbeam Specialties. This is my second time building this motor - the first time it ran fine but one of the rings failed to break in properly. I had the block honed and bought new rings and I'm reassembling now. Aside from excessive blowby the car ran fine, but the distributor was rotated such that the vacuum canister ran into the dipstick. That's the issue I am troubleshooting now as I want to avoid repeating that mistake again.
     
  3. mightyohm

    mightyohm Gold Level Sponsor

    I'm confident the pump and cam are matched and have the correct # of teeth for a 1725.
     
  4. mightyohm

    mightyohm Gold Level Sponsor

    Sorry if I was confusing - I rotated the crank and then reinstalled the oil pump to achieve the proper angle. If I leave the pump installed and rotate the crank 360, the pump drive moves the expected 180 degrees..
     
  5. mightyohm

    mightyohm Gold Level Sponsor

    Tom, I measured those two images - looks like 45-46 degrees, very close to the WSM spec. Are these 1592 or 1725 motors?
    I'm stumped.
    Untitled-1.jpg
     
    Last edited: May 29, 2019
  6. 65beam

    65beam Bronze Level Sponsor

    Dan,
    I seem to remember something about Peugeot casting blocks in France in the late 70's/early 80's. If think Rick @ SS told me about this. This block has the side mounts for use in the Arrow range. They're the same as any earlier 1725 except for that. I've never seen anyone stamp numbers on the sides of the cylinders.
     
  7. Tom H

    Tom H Platinum Level Sponsor

    Jeff, The pic with the red line on a white paper is a 1600. The red block is a 1725. Both are exactly as I have seen. And I have matching pics of these same blocks and set ups, where the oil pump was installed incorrectly with the wrong orientation of the heavy side of the drive, which achieves the same wrong angle you are seeing. BUT your situation appears to be different.
     
  8. Tom H

    Tom H Platinum Level Sponsor

    Thanks for this clarification. Now I see that it shows EXACTLY what I expected - AND what you should expect . See my earlier note:

    " It seems you DO have the engine at #1 TDC Firing, based on the cam lobe positions. The only explanations I can think of is 1) the the oil pump gear has the slot machined offset to the wrong side. or 2) the timing chain if off by a tooth or two. My suggestion, assuming explanation #1, would be to install the oil pump approx 180 deg rotated such that the proper angle is achieved but with the slot on the wrong side. Then install the dizzy with the rotor 180 deg wrong, and shift all the wires in the cap 2 positions. This will put the dizzy in the normal orientation at normal timing.".

    This because the gear has an odd number of teeth. As your fist pics showed, when installed with the slot "correctly" off center, you were always a half tooth off. But when you rotate the gear approximately 180, ( plus or minus a half tooth) it aligns correctly but with the slot on the wrong side.

    What you accomplished is, for all intents and purposes, exactly what I suggested above. Except that you rotated the crank 360 before re-orienting the pump. If you now turn the crank once again 360, you will be exactly where my sequence would have put you, i.e. with the slot at the correct angle , but with the slot offset to the wrong side. Again, as noted above it is easy then to install the dizzy with the rotor pointing exactly 180 deg from standard. Then simply move the wires on the dizzy cap 2 positions over , and the dizzy will have the correct original orientation.

    The above solution only works assuming that the problem is an incorrectly machined oil pump gear.

    The other possibility is that the timing chain is off by one or two cam gear teeth !!!! How sure are you about the timing gear alignment ? Did the dots line up with the centerline of the crank shaft and camshaft? From the set of 3 photos you have shown it appears that when installed correctly according to the WSM the oil pump slot angle is clearly off by half a gear tooth - about equal error either way you install it, and at the correct angle when slot is totally reversed. So 1/2 tooth error. 360 deg at 11 teeth is 32.7 deg per tooth or 16.35 deg per half tooth. So off from the stock 47 deg by +16.35 or -16.35 deg.

    I count 40 teeth in the WSM dwg of the cam gear. 360 deg at 40 teeth is 9 deg per tooth or 18 deg per 2 teeth. It seems to me that 18 deg error, is very close to the 16.35 deg error we see in the photos of the slot in the oil pump gear.

    If there is a machining error in the oil pump gear, it's an easy work around as noted above. But if it's a 2 tooth error installing the cam gear, that's a problem.

    Do you have or have access to another oil pump to compare with? Easier than removing the timing cover. OR there is a procedure in the WSM on page B 25 for checking the timing chain installation after assembly.

    Tom
     
    Last edited: May 30, 2019
  9. mightyohm

    mightyohm Gold Level Sponsor

    I have several oil pumps on hand and have tried two of them so far. Both pumps had the slot on the same side and yield the same installed angle, so I don't think it's a mis-machined gear.

    Rotating the crank another 360 degrees won't "fix" the angle of the pump - it would spin it 180 degrees from its current location. I'd have to rotate the crank AND move the pump a tooth in order to achieve the desired 48 degree angle.

    I attached a couple photos showing my timing marks.

    IMG_6808.jpg IMG_6813.jpg
     
  10. Mike O'D

    Mike O'D Gold Level Sponsor

    If you take the slack out of the chain at the bottom where the tensioner goes do the marks still line up with a straight edge lined up on the centers of the gears?
     
  11. Tom H

    Tom H Platinum Level Sponsor

    When I lay a straight edge along the centerlines of both Crank and camshaft in your photo the two dots are both to the right of the straightedge. If I rotated the crank (CCW) a bit to get the crank dot on the centerline, the cam dot will move further away from the straightedge. and when you remove the slack on the tight line by pushing on the tensioner to take up the slack, it adds a bit more and looks like it would then be about 2 teeth away. As I see it, that's the problem. It looks like you got the dots lined up with each other, but not on the shaft centerlines.

    The fact that you have tried other pumps, convinces me that the issue is NOT a mis-machined gear. The issue is clearly a mis-aligned timing chain. And the photo confirms it. I can't tell if it's off by one tooth or two. But note that the alignment must be checked with no slack on the right side of the chain. all slack taken up on the left side.
     
    Last edited: May 30, 2019
  12. mightyohm

    mightyohm Gold Level Sponsor

    Tom,

    I think it may be hard to judge by the photo because of parallax and the fact that the photo wasn't taken perfectly orthogonal to the gears. I looked through my other photos and found a couple that I think show the alignment more clearly. The alignment looks pretty close to me.

    2019-05-31_1-03-56.jpg
    2019-05-31_1-16-13.jpg
    2019-05-31_1-21-30.jpg

    To confirm this, I measured cylinder #1 intake valve timing per the WSM and I get about 27-29 degrees BTDC which is very close to spec for the 1725 (29 degrees BTDC @ 20 thou rocker clearance). I measured this by looking for a tappet lift of 14-15 thou using a dial indicator. This corresponds to the 19-20 thou rocker clearance + 1 thou lift as called for in the WSM procedure for checking cam timing. I divided the gross lift (rocker clearance+valve lift) by 1.4 to compensate for the rocker arm ratio since I am measuring at the lifter (no valvetrain installed yet). If the cam was one or more tooth off then the valve timing should be off by 18 degrees of crankshaft rotation per tooth - I think this would be very noticeable.

    I also installed a spare cam, crankshaft, timing set, and oil pump in another block I had on the shelf. That one also exhibits the same problem. The oil pump sits at 32 degrees, not 48 degrees, when the motor is set for TDC #1.

    If anyone has a 1725 and can confirm this please see if the oil pump matches this template with the motor at TDC #1:
    https://www.dropbox.com/s/m723pjyof57ary4/oil_pump_drive_template_32_20190531.pdf?dl=0
     

    Attached Files:

    Last edited: May 31, 2019
  13. Tom H

    Tom H Platinum Level Sponsor

    Jeff, All those photos show the alignment with the chain slack on the right side. You must check the alignment, including your tappet test, with the chain fully tensioned on the right side, as it is tensioned when running. This applies to any timing testing or setting. When you are setting the crank to the TDC position, while cranking Clockwise, of course, if you overshoot the mark, which is common, the tendency is to back up the crank to the mark. But this will always result in a slack chain. If you back up the crank at all you must back up enough that the cam moves, and THEN crank forward carefully to the mark. When doing alignment with the timing cover off it's easy to just push on the chain where the tensioner would push until the slack is all taken up on that side, and the cam shaft rotates to the correct position, and the critical timing side is tight. I have sent you two pics from 2 different motors owned by 2 different people and they clearly show the correct angle. I have rebuilt Alpine engines 3 times and have always seen the correct angle, except when the gear was installed with the slot on the wrong side. If it does not line up like the WSM shows, something is wrong. I guess one more possibility is that the you backed up the crank rotation after overshooting, or maybe even did all the rotating CCW, which would emphasize the chain slack issue and that all the misalignment is due to that slack issue. I have attached one more pic, it''s of MY assembled 1725 after rebuild, you can see pistons 1 and 4 at TDC and you can see the oil pump drive slot is pretty close to the "approx" 45 deg angle. This pic was not taken for any critical purpose and the chain may not be in tension, but it's pretty clear that the gear is not off by any significant amount. Also look at the second pic, with the crank rotated about 90 deg, with all pistons halfway down or up, and the dizzy gear slot is rotated about 2 deg or so past vertical. You might try that. But again rotate CW, and no backing up. If it does not line up correctly something is wrong. The angle spec'd in the WSM is not in error!
     

    Attached Files:

  14. mightyohm

    mightyohm Gold Level Sponsor

    Tom,

    The tappet test was performed with the chain tensioner and timing chain cover installed. The pictures are from before I installed the timing chain tensioner. The test was performed by setting the crank to some distance before 60 degrees BTDC, verifying there was no movement of the tappet with small changes in crank position, zeroing the dial indicator, and then turning the crank CW until the desired tappet lift was achieved. (One caution for others trying this test, if you zero the indicator at 60 degrees BTDC you won't get the proper result because there is already a small amount of tappet lift at this crank position. You have to back off past the point where there is NO lift and then turn purely CW without reversing as Tom suggested.)

    One other complicating factor here - I tested all of the oil pumps I have on the shelf here, and one of them (a new pump purchased from SS within the last two years) has the slot clocked slightly differently than the rest and results in a pump angle much closer to the 48 degree spec. I also have a replacement drive gear (new old stock) that appears to have the same offset as the SS pump, although I haven't installed it on a pump yet so I can't check. The majority of pumps I have on hand agree with the first pump I tried (in the photos at the top of the thread). As a result I don't think we can take it as a given that all oil pumps are the same, and this will definitely result in the drive angle changing depending on which pump is used.

    I see what you are saying about the chain slack - I should have done a better job of getting rid of the slack when i took the photos. I think it's unlikely I am off a tooth given that the cam timing test passed but I'll take a closer look.
     
    Last edited: May 31, 2019
  15. 65beam

    65beam Bronze Level Sponsor

    Where is the timing chain tensioner? Or am I not seeing it?
     
  16. Tom H

    Tom H Platinum Level Sponsor

    The tensioner is there, dangling at the lower left in some of the pics that are wide enough. You can just see the peg, washer, cotter pin, and the pivot end of the rubber tensioner. It really only gets held into position when you put the timing cover on.
     
  17. 65beam

    65beam Bronze Level Sponsor

    I'm aware of how it fits. It may be tough to fit the cover with the chain as snug as the photos show.
     
  18. mightyohm

    mightyohm Gold Level Sponsor

    Today's progress:

    Cam timing verified again to be approx 25-27 degrees (close to factory spec of 29 degrees). The results are for cyl #1 intake. If cam gear was off by a tooth this number should be 18 degrees high or low, so I don't think that's the problem. I used a degree wheel this time. See photos.
    2019-05-31_15-47-14.jpg 2019-05-31_15-48-14.jpg
     
  19. mightyohm

    mightyohm Gold Level Sponsor

    Next I checked the effect of chain slack on my "test mule" 1725 engine. There is very, very little movement due to chain slack, maybe a degree or two at most. It is absolutely not possible to mis-align the gears by a tooth due misjudging alignment caused by slack in the chain. You could make the argument that I'm not pushing hard enough on the chain, but I checked - there is NO discernible movement in the cam gear beyond what is shown in the photos.

    2019-05-31_15-51-26.jpg 2019-05-31_15-51-45.jpg
     
  20. mightyohm

    mightyohm Gold Level Sponsor

    Next, I put a straight edge on the gears to check alignment of the dots. This becomes TDC #4. The cam gear is in the 2 o'clock position as shown, and the dots are perfectly aligned.

    2019-05-31_15-55-21.jpg

    Then, I rotated the engine 360 degrees, to TDC #1. I pushed in on the tensioner side of the chain to take out any extra slack. The crankshaft is at TDC and the cam is in the 8 o'clock position.
    2019-05-31_15-57-19.jpg

    Then, I installed an oil pump that is representative of the majority of oil pumps on my bench - this pump shows 32 degrees alignment in the first post in this thread.

    The pump does not align with the 48 degree template.
    2019-05-31_15-59-54.jpg

    It does align with the 32 degree template.
    2019-05-31_16-00-55.jpg

    Note that in the photos of the timing chain, I haven't pressed the gears all the way onto the shafts. This is so that I can remove them more easily (see my other post about seeking a good puller). As a result, the cam will tend to sit too far back in the block since the gear is not pulling it to the front - this affects oil pump alignment. In order to get an accurate measurement of the slot angle, I am gently preloading the cam towards the front of the block to remove any excess end play. This will be very close to the normal running condition.

    So, where does this leave us?

    We know cam timing on my motor is correct, because I measured it according to the method in the WSM, using tappet lift in lieu of valve lift and compensating for the rocker arm ratio of 1.4.

    We know that chain slack does not significantly affect cam timing (or cause misalignment of the dots) because the effect is so small (at least on a new chain or one in good condition).

    We know that the majority of pumps in my shop (4 out of 5) result in a 32 degree angle of the drive slot @ TDC #1. One pump (purchased in 2017 from Sunbeam Specialties) has a different slot offset and yields the desired 48 degrees. By the way, if I rotate the motor to TDC #4, and THEN install the pumps, the the situation is suddenly reversed - 4 out of 5 pumps yield 48 degrees and one pump yields 32 degrees. So not all pumps are created equal and that may explain why folks get different results. Amusingly, most of my 1725 pumps that have been harvested from old motors (some not running in 20+ years, so these are old pumps) have different casting marks and part numbers. They all say Hoburn Eaton but I have no idea if they are original or copy-cats. I'm not surprised that there is some variation in pumps - some of them may have even been intended for the Iranian Paykan (I'd love to see a workshop manual for that car!).

    I built a second motor to show that it has the same problem - the majority of oil pumps in my shop show a 32 degree angle when the cams are properly timed and the pump is installed when the motor is set to TDC #1. I think this double-confirms that the cam timing for the first motor is correct, since i get exactly the same results on a second motor in which I have shown precise alignment of the cam dots with a straight edge.

    I think Rootes made a mistake when they put the 47-49 degree number in the WSM for the 1725. I think they forgot to change the number when they changed the number of teeth on the gears from 12 to 11 teeth. The 47-49 degree figure is only valid for a 12 tooth cam/pump combination. Rootes removed the figure from the Hunter manual and I think by that time they had realized their mistake. It also seems that some oil pumps (such as the ones Sunbeam Specialties is selling) have the slot in a slightly different position in order to correct the situation, so depending on what oil pump you have on hand you might be able to achieve the 48 degree rotation, or not. On the 1592 (and maybe earlier motors?) there is no problem - the symmetric nature of the drive gears means that you can always achieve a 48 degree angle regardless of TDC #1 or #4.
     
    Last edited: May 31, 2019

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