DIY cam swap...breaks engine... (update)
Thread Starter
Pro
Joined: Apr 2008
Posts: 525
Likes: 1
From: Vancouver BC
I have done the heads on that car something like five times, and the valve springs many more times. I purchased/tried a variety of different spring compressors and the one that worked best for me (by a wide margin) was Tim's Valve Spring Tool. It seemed ironic to me that out of all of the different spring compressors I bought that such a simple looking tool worked so amazingly well.
JIC?
Racer
Joined: Dec 2010
Posts: 418
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From: South Central Kansas
The loctite was missed, and the torque wrench I had at the time was kinda screwy so I am not sure if the lack of loctite is entirely to blame.
Try to imagine how much time I spent researching loctite (different types, different strategies for application etc) the next time around! Same holds true for torque wrenches and their proper use!
Try to imagine how much time I spent researching loctite (different types, different strategies for application etc) the next time around! Same holds true for torque wrenches and their proper use!
Thanks
Bob
Thread Starter
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Joined: Apr 2008
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From: Vancouver BC
https://picasaweb.google.com/lh/phot...eat=directlink
https://picasaweb.google.com/lh/phot...eat=directlink
After the broken components had been removed from the car I took a picture of the bolts themselves.
https://picasaweb.google.com/lh/phot...eat=directlink
I think the picture above provides a clue as to what happened. The bolts backed out (due to either lack of loctite, or lack of loctite plus possible misuse of torque wrench). As the bolts backed out, the cam shaft sprocket was no longer "clamped" to the camshaft and the camshaft sprocket started riding on the bolt shafts. Zoom in on the last picture and you can see where the camshaft sprocket was riding/wobbling on the bolt shafts.
What is a bit hard to figure out is what was the final straw. Did the camshaft bolts back out far enough that the camshaft sprocket had so much deflection and wobble that everything busted up? Or did the camshaft sprocket ride on the camshaft bolts until the bolts(s) broke? Regardless of what the final straw was, the bolts backing out appears to be the source of the issue.
Thread Starter
Pro
Joined: Apr 2008
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From: Vancouver BC
After rereading your question I think I better understand what you are asking. I think you are asking whether or not it was possible that the bolts were overtightened/strained with the torque wrench, and then broke off because of being over torqued? I do not believe the issue was that they were overtightened. I do not believe they were over tightened for two reasons. The first reason is because of the previous answer I have given (the pictures point to the bolts having backed out). The second reason is because when the bolts were being torqued I remember at the time that very little torque was used when tightening and I was surprised/worried at how little torque was being applied. In hindsight my concern was justified. :-)
Racer
Joined: Dec 2010
Posts: 418
Likes: 0
From: South Central Kansas
After rereading your question I think I better understand what you are asking. I think you are asking whether or not it was possible that the bolts were overtightened/strained with the torque wrench, and then broke off because of being over torqued? I do not believe the issue was that they were overtightened. I do not believe they were over tightened for two reasons. The first reason is because of the previous answer I have given (the pictures point to the bolts having backed out). The second reason is because when the bolts were being torqued I remember at the time that very little torque was used when tightening and I was surprised/worried at how little torque was being applied. In hindsight my concern was justified. :-)
Thanks
Bob
Thread Starter
Pro
Joined: Apr 2008
Posts: 525
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From: Vancouver BC
I understand...I am contemplating a cam swap and after reading about your situation and viewing the photos I became just a little nervous about the swap. It would not be good to go through all the time, trouble and cost of swapping cams to have it come apart. Somekind of locking plate or special washer or safety wire on the cam bolts would be comforting! I very much appreciate the response.
Thanks
Bob
Thanks
Bob
