Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15

Thread: O-200 Won't Start, Cough, or anything...

  1. #11
    CarlOrton's Avatar
    Join Date
    Jul 2011
    Location
    DFW Area
    Posts
    710
    Quote Originally Posted by cub builder View Post

    Rereading your reply, you have it firing 90 off. If it was me, I would make sure the mags are timed to #1 cyl at TDC on the compression stroke, then simply follow your plug wires and put them on in firing order. It's an easy fix you should be able to do in pretty short order.

    Good luck with it.

    -Cub Builder
    Just want to make sure I understand. You ARE saying to remove the mags and retime, correct? Or are you saying simply reroute the wires to move them 90 off? All of my plug wire caps are stamped with T1, B1, etc so it would be simple to move cyl #2 wires to plugs 1, etc. What a nightmare in future repairs though!!

    Carl Orton
    Sonex #1170 / Zenith 750 Cruzer
    http://mykitlog.com/corton

  2. #12
    cub builder's Avatar
    Join Date
    Nov 2011
    Location
    North Central AR
    Posts
    450
    Quote Originally Posted by CarlOrton View Post
    Just want to make sure I understand. You ARE saying to remove the mags and retime, correct? Or are you saying simply reroute the wires to move them 90 off? All of my plug wire caps are stamped with T1, B1, etc so it would be simple to move cyl #2 wires to plugs 1, etc. What a nightmare in future repairs though!!

    One more thought which might explain why things would be off by 90. If you are aligning the timing marks on a flanged O-200 crankshaft with the part line on the case, it should be aligned with the split in the case BELOW the prop hub. If you aligned it with the TOP of the case above the prop hub, you will be 90 off on the magneto timing. If this is the case, remove the magnetos, pin them correctly as outlined above, set the crank to the correct timing 20 BTDC mark aligned with the case part line below the crank flange) and re-insert the magnetos. Finish timing with a timing tweeter, then fire it up. This scenario would exactly match the symptom you described with #4 firing when you expected #1 to fire, so may very well be the issue. If it is, you'll recognize the error as you read this.

    I'll write another post as a followup to answer your question above, but I have a sneaking suspicion that this post may cover your issue.

  3. #13
    cub builder's Avatar
    Join Date
    Nov 2011
    Location
    North Central AR
    Posts
    450
    Let's see where the mistake lies. Shown in the photo below, there is a #1 stamped into the cover right next to the #1 plug lead. Make sure that goes to #1 cylinder. If this is a left hand rotation, which I believe it is, then follow the leads in firing order around the clock to make sure they are numbered correctly. Firing order is 1,3,2,4 It is always possible that you could have a harness for an A series Continental (-R rotation) mounted to a magneto for a C series (O-200) engine (-L rotation). Since the magnetos turn the opposite direction, that would really foul things up. So let's make sure that is correct first.
    Name:  Slick harness.jpg
Views: 183
Size:  4.6 KB

    If the plug leads are numbered correctly, then lets make sure they are going to the correct cylinders. Back right is #1, back left is #2, front right is #3 and front left is #4. Firing order is 1,3,2,4. Make sure they are in that order with the rotation of the magneto.

    OK. A point of clarity here. The extension on the part number on the magneto should end with either -L or -R. That does not signify left or right magneto. It stands for the rotation of the magneto. Both of yours should have a -L and the timing pin should be inserted into the L hole as shown below. I'm always surprised at how often this trips up builders.

    If you have the correct plug leads going to the correct cylinders, and they were all labeled correctly, then you will need to remove the magnetos, pin them correctly with the timing pin inserted into the correct timing hole, then through the matching timing hole in the distributor cap. The timing pin should slide all the way in to the first shoulder as shown in the photo below. Re-install the magneto with the crank set at roughly 20 BTDC on the compression stroke of #1 Cylinder. Once both magnetos have been installed, use a timing tweeter to fine tune the timing to the correct setting. Reinstall the harnesses and fire it up.
    Name:  magneto.jpg
Views: 173
Size:  5.1 KB

    One more thought which might explain why things would be off by 90. If you are aligning the timing marks on a flanged O-200 crankshaft with the part line on the case, it should be aligned with the split in the case BELOW the prop hub. If you aligned it with the TOP of the case above the prop hub, you will be 90 off on the magneto timing. If this is the case, remove the magnetos, pin them correctly as outlined above, set the crank to the correct timing 20 BTDC mark aligned with the case part line below the crank flange) and re-insert the magnetos. Finish timing with a timing tweeter, then fire it up. This scenario would exactly match the symptom you described with #4 firing when you expected #1 to fire, so may very well be the issue. If it is, you'll recognize the error as you read this.

    This is pretty straight forward and simple stuff. Any A&P or your EAA Tech Counselor should be able to help you sort this out in an hours time. I'm going to be away from computers for the next week, so this is all I can offer for now.

    Good luck with it. And let us know what you find once you isolate the problem.

    -Cub Builder
    Last edited by cub builder; 03-03-2022 at 03:50 PM.

  4. #14
    Dana's Avatar
    Join Date
    Jul 2011
    Posts
    887
    Quote Originally Posted by CarlOrton View Post
    ...it would be simple to move cyl #2 wires to plugs 1, etc. What a nightmare in future repairs though!!
    Yeah, it might fix your problem but it's a really bad idea. That said, I swapped the wires on a half VW with a Slick mag in order to make the wires reach... but it's only two cylinders to troubleshoot, and I noted it in the engine log.

    Reminds me of the trouble I had years ago trying to get a a rebuilt Pontiac 428 to run... I had only worked on small block V8s and didn't realize big block distributors turned in the opposite direction.

  5. #15
    CarlOrton's Avatar
    Join Date
    Jul 2011
    Location
    DFW Area
    Posts
    710
    Solved and fixed. And catastrophe averted.

    As y'all were typing your hints above, I was out solving things. Took less than an hour.

    Pulled both mags after setting #1 to the top of the compression stroke. Re-installed the installation pin, and installed them one at a time. Finalized with the timing tweeter.

    Cranked. No start. Grrr... Shot some ether into the breather. 1/2 a revolution later, it fired up. In my garage. I had stuff cleared away, so after the first cloud of detritus blowing all over, it hopped the wheelchocks and headed for the car parked in front of it. Got about a foot, then died. Didn't have a fuel tank hooked up, so I guess it burned thru the fuel in the fuel bowl.

    I ALWAYS (well, obviously, ALMOST always) start an airplane engine outside and strapped down. I figured this would barely lope a bit, or even run rough, so I took my chances. Fortunately, I had stuff cleared out of the way, and I *assumed* that the wheel chocks would hold. Never assume.

    Based on what cub builder noted above, I'm assuming that I installed the mags with the timing marks 180 out. I KNEW about the timing marks being registered to the bottom crankcase seam. I even cut=out the section of the OH manual nothing that, and sent a screen capture of the OH video showing that to my mag guy. There was enough time between receipt of mags and installation that that's the only answer that makes sense. I *know* (knew?) that I inserted the timing pin in the L hole in the mag, and *knew* both mags matched with the tweeter.

    One bite of the elephant at a time.

    Carl Orton
    Sonex #1170 / Zenith 750 Cruzer
    http://mykitlog.com/corton

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •