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twisted cambelt


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I went to try and start my 300 90 engine for the first time in a month yesterday as it's been out for the galvi rebuild. At first it started fine and ticked over for a bout 10seconds then cut out instantly. I removed the timing cover to find that the cambelt has somehow twisted itself around twice but is still just on the pulleys. is that because I didn't tighten the new belt enough or too much?? and how likely is it that i've caused any other damage?? I havn't dared to look yet

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well ive fitted new pushrods and a new belt and tried firing it up but still no joy. I can't work out which way the cam sprocket is supposed to be round, I've tried removing the belt and turning the cam by 360 and trying again but it wouldn't start either way. is there a way to find out which way the cam is supposed to be?? It's locked at TDC on the no1 cylinder so I guess that if I look at the valves and see which are compressed I could tell if it's right but I don't know which valves should be down and which shouldnt? if anyone could tell me it'd be great :D! I've had the belt on and off too many times to remember now :angry:

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well ive fitted new pushrods and a new belt and tried firing it up but still no joy. I can't work out which way the cam sprocket is supposed to be round, I've tried removing the belt and turning the cam by 360 and trying again but it wouldn't start either way. is there a way to find out which way the cam is supposed to be?? It's locked at TDC on the no1 cylinder so I guess that if I look at the valves and see which are compressed I could tell if it's right but I don't know which valves should be down and which shouldnt? if anyone could tell me it'd be great :D! I've had the belt on and off too many times to remember now :angry:

Moving the cam around 360 degrees just puts it back in exactly the same posistion as before (doesn't it?). The crank turns twice for every one revolution of the cam so if the crank is at TDC & the cam is pointing to the timing marks is it the pump timing?

Have you checked the valve clearances? If they aren't set the valves might not be closing so you won't be getting propper cylinder pressures to ignite the fuel. Does it sound normal when turning over?

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In order to know whether it is number one cylinder that is on the firing stroke, the valves on cylinder number four should be rocking as you come to TDC. ie. the exhaust valve is closing and the inlet valve just starting to open.

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Hello, thanks for the replies. After spending most of today removing the cambelt numerous times and removing the head to check the valves hadn't got damaged, I then (after reading your post) adjusted the tappets and it fired up straight away. Oh well, thats how ya learn :rolleyes: ! thanks v much again

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