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Thread: Tornado Engine Rebuild Questions

  1. #1

    Default Tornado Engine Rebuild Questions

    I am in the process of reassembling my Tornado engine after rebuilding the head and putting a new piston in cylinder #6. I have a couple of questions.

    How tight should the timing chain be? My seems loose but it looks to be in good shape. I did not see anything in the manual about checking the timing chain to see if it needs replacement.

    Second, I know this has been discussed somewhere but maybe someone could refresh my memory. The rebuild gasket set that I purchased from Memphis has a rear main seal that is significantly different than the one that was in there. It is smaller but seems to fit in the slot ok and is the right diameter, but it is not u-shaped like the one that came out. Will it work ok? As the other type of seal still available? If so where can I get one. It looks like it would seal much better but the one that was in there is definitely worn and brittle.

    Thanks in advance for any help. I will try and post some pics later tonight.

    Tom
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  2. #2
    Join Date
    Dec 2003
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    SF Bay Area, CA
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    Default

    I've had good luck with the civilian style rear main seal which is probably what you have.

    see this thread:

    seal question


    As far as the timing chain being somewhat loose, one thing comes to mind. Did you have the cylinder head surfaced? That brings the cam timing gear closer to the crankshaft gear, causing a looser timing chain. When mounting the timing cover, you will have a noticeable "step" between the valve cover surface of the head and the top of the timing cover. Normally they are the same height. Felpro made a thicker composite cylinder head gasket to compensate for the surfacing. Unfortunately no longer manufactured but sometimes shows up on ebay. It does not have the "triangle wings" on the forward end of the head gasket, like the metal military version, but a filler can be fabricated out of gasket material to fill the void.

    I don't know of any spec's for timing chain wear.
    Last edited by hiker; December 11th, 2010 at 10:18 PM.

  3. #3

    Default

    Quote Originally Posted by Rocntj View Post
    I am in the process of reassembling my Tornado engine after rebuilding the head and putting a new piston in cylinder #6. I have a couple of questions.

    How tight should the timing chain be? My seems loose but it looks to be in good shape. I did not see anything in the manual about checking the timing chain to see if it needs replacement.

    Second, I know this has been discussed somewhere but maybe someone could refresh my memory. The rebuild gasket set that I purchased from Memphis has a rear main seal that is significantly different than the one that was in there. It is smaller but seems to fit in the slot ok and is the right diameter, but it is not u-shaped like the one that came out. Will it work ok? As the other type of seal still available? If so where can I get one. It looks like it would seal much better but the one that was in there is definitely worn and brittle.

    Thanks in advance for any help. I will try and post some pics later tonight.

    Tom
    I had mine replaced a few weeks ago. The rear main seal from Memphis does look different, but it works and seems to be the only one out there. I have been told the original style has been discontinued and is no longer available. I was thinking about getting another one for a spare to keep on hand, but I would like to find a cheaper source than Memphis. Good luck.

  4. #4

    Default

    Thanks for the feedback. That is what I remembered about the oil seal. It looks like this one should work but it is not near as stout as the one that was in there. Here is a picture of my timing chain. Seemed loose to me but I went ahead and put it back together. If it doesn't work I can take it apart again and replace it.

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  5. #5
    Join Date
    Sep 1998
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    Default

    the -34 manual, Chapter 3, Section 2, says:

    Check the chain for excessive wear or stretch. When the chain is installed measure the distance between the chain sides at the narrowest point. This distance should not be less than 3.38-inch. If the distance is less than required, the chain has stretched or is worn excessively and the chain and sprockets must be replaced.
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  6. #6

    Default

    I knew that was in the manual somewhere but could not find it this weekend when I was putting things back together. Maybe I can scale the distant from my pictures. Thanks for the info brute4c.
    M715
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  7. #7

    Default

    Remember that the timing chain is tighten through 2 different areas. One is the little plastic arm in the block with the 2 screws which typically goes all the waym and then there is the large plastic arp with the spring that takes care of the rest within the chain cover. Can you identify the two?

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