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trexxs

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About trexxs

  • Rank
    Newbie

General Info

  • Location
    Australia QLD
  • Car Type
    Nissan Silvia
  • Car Model
    180sx
  1. Problem sorted. My friend brought over the spare exhaust cam sprocket and from matching the mark onto the teeth of my existing sprocket I found that the exhaust cam was retarded by one teeth. My method of fixing this was to take out the tensioner and turn the crank counter-clockwise to slacken the chain on the exhaust side. Then I simply lifted the chain over the exhaust sprocket by one teeth. To avoid a repeat of the chain skipping a teeth again when releasing the tensioner, I simply turned the crank clockwise until the chain was tight between the sprockets and between the exhaust cam sprocket and crank gear, leaving the tensioner side chain at full slack. Now I really should've known this crucial step as I have done a fair few timing belts as a current apprentice. However the reasoning was never explained to me and I just assumed that it was to make sure the non tensioner side timing was correct. WRONG, well not entirely, as I have learnt from my mistake. The main reason is to prevent any movement of the cams or slippage of the belts when releasing or setting the tensioner. While it's not a critical step as mistimed cams can easily be corrected when full access is available, however this becomes a critical step when there is only limited access and you want to avoid removing the cams, something that is not mentioned in the fsm. Now if you had shitty China cam sprockets like mine that lacked any holes to zip tie the chain, tensioning the non tensioner side chain and allowing the tensioner side to slacken is a must before releasing the tensioner with the fsm method. In fact, if you only had small and thin zip ties to tie the chain, it's a better idea to just forgo the zip ties and use the method above to prevent any zip ties breaking and falling into the crank case, and skipping a teeth in the end anyway. Happy wrenching!
  2. Good point! I didn't even consider getting another sprocket to compare. I actually have a couple lying around from engines I've stripped but they've been stashed at my mates place for a while so it never crossed my mind. I'll go dig em up Cheers!
  3. Hey mate, thanks for the response. However, the issue right now is that the cam sprocket marks CANNOT be used to verify cam timing. Why? Because on all exhaust cam sprockets, as depicted in the fsm as well as various other images and general consensus of the marks, the timing mark is located AFTER the exhaust cam dowel. My exhaust sprocket mark is BEFORE the dowel. Meaning when the exhaust cam dowel is at 12 o'clock, the mark should normally be at the 1:30 position, however, mine will NEVER be in that position and will always be at the 11 o'clock position unless the exhaust cam is advanced forward, which we obviously don't want. Therefore the guideline to verifying cam timing by counting links between sprocket marks cannot be used to verify the timing,as far as I'm aware. Now if the crank is set at tdc timing mark, piston no. 1 will be at tdc regardless of cam position. So the engine right now is in fact at tdc, however, valve timing may be an issue as none of my sprockets had holes in them to zip tie the chain when releasing the tensioner. The only things I can verify now is the general direction the cylinder 1 cam lobes are facing, which are correct, and the mark on the CAS, which is correct. But these are not concrete evidence of correct valve timing.
  4. https://imgur.com/a/BAHTG Well I went and replaced my timing chain tensioner on my vct sr20det today without putting the engine on TDC first as I didn't think the chain would jump when releasing the tensioner with the factory method. Nek minnit, not too sure if it did jump or not, or if it was just the sound of the tensioner releasing (sounded like a loud crack) but I went and put the engine on TDC to verify cam timing and what I saw got me confused. Cylinder 1 was at TDC compression stroke, cam lobes pointed out, exhaust cam dowel at 12 o'clock BUT the mark on the exhaust cam sprocket is at about 11 o'clock, before the dowel, instead of being located after the dowel at about 1 o'clock as all other sr20det's have it. To make matters worse the timing chain does not have any coloured links on it. So after 2 hours of research I couldn't find a single answer to this predicament. How else would I be able to check cam timing apart front pulling shit out and counting the links from the crank gear? Maybe I should just whack on the valve cover and try and start it, see what happens. Any help would be appreciated, Cheers
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