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dmcmunn@penn.com
Posts: 1
Joined: Tue Sep 12, 2000 7:51 pm

update on broken a-13

Post by dmcmunn@penn.com » Tue Sep 12, 2000 8:51 pm

What I found so far: The cam timing is off by at least 2 teeth. The cams are OK in relation to each other, but are both advanced from their correct position at TDC. Neither had valves opening at TDC, but this might explain the sudden power loss, but does it explain the horrific noise also? Is their a chance I bent valves at 2 teeth advanced? Why did the cams jump time? I took the adjuster out and it seems to be applying pressure as it should. On top of everything else, I dropped a cam cap collar down the spark plug hole! I think I can retrieve it though. Should I pull the head anyway and check for damage? Also, is the base of the compression release mechanism supposed to be splayed slightly off of a perpendicular axis with the cam? The weights seem free enough, but the base looks bent to me. Any thoughts are appreciated, and thanks to everyone that responded earlier. Dave

David/Diane McMunn
Posts: 15
Joined: Sun Aug 13, 2000 8:12 pm

update on broken a-13

Post by David/Diane McMunn » Tue Sep 19, 2000 10:14 pm

I finally found the reason for the breakdown. When I got the rotor off to check the balancer and cam chain tensioners, I found that the balancer tensioner spring had broken. The broken piece had gone through the camchain lower sprocket, by the looks of it, and caused the chain to jump. Has this failure been known to occur commonly? I hadn't seen anything on the list about it. I can find no other damage, and plan to get the new parts and see what happens. BTW, I removed the balancer chain and retimed it. I think it was OK, but it seems to take many engine revolutions to bring the marked links into the proper place to check it exactly, so I just started over and did it by the book. Don't know if this will solve the awful clatter I had when this happened, but can't find anything else wrong. No bent valves, etc. Would one out of time by two teeth sound like a thrashing machine? I also had the bad luck to have this problem right when the list went down, so many may not have seen my prior post. Thanks again to all who responded. Dave

Krgrife@aol.com
Posts: 806
Joined: Thu Apr 06, 2000 9:32 pm

update on broken a-13

Post by Krgrife@aol.com » Wed Sep 20, 2000 11:52 am

In a message dated 9/19/00 8:16:02 PM Pacific Daylight Time, dmcmunn@... writes: >>
Dave- I've just been through a total rebuild of this system and there is one crucial thing for you to check. The dual sprocket that is pressed on the crankshaft and which drives the cam and balancer chains has an index dot which must be pointed at the center of the crankpin. Since the two drive sprockets are fixed in relation to each other if the sprocket has turned at all on the crank (as mine had) you cannot time the balancer relative to the crank and cam position. I'm going to do a final post on my rebuild project in the next few days. If I can be of any other help don't hesitate to e-mail me directly. Kurt Grife