Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: SKlein on Wednesday,April 23, 2025, 03:14:51 PM
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I can't get my inlet cam sprocket mounted:
I had the head off my engine & had it checked over, resulting in new guides & valves etc. Stock cams reused, no head skimming, bottom end not touched. Timing cover not removed. Chain not touched except to hang it on a wire from above. The only dimensional change is due to a new head gasket from RD. Reinstalled the head, crank is at TDC, cam sprockets all line up correctly (without the chain). Exhaust sprocket w/chain mounted & aligned. I can't get quite enough chain slack to mount the inlet cam sprocket. It should be easy, right? I think there might be a problem with the chain on the jackshaft sprocket preventing the needed slack up above. Does that sound typical? I thought maybe the jackshaft needs to be turned a little, but can't budge anything by pulling on the chain. Am I missing something here?
Thanks,
Steve
TCS 44519R
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How much does the sprocket miss its mounting on the cam?
Have you undone the tensioner bolt to give a bit more slack?
Once you have mounted the sprocket, then you can move the engine through a complete rotation and re-tension the tensioner bolt.
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The tensioner adjusting bolt & plug are removed, so that's free to move. I think I need one or two links of slack to get the sprocket mounted. I'm going to try removing the tensioner assy, to see if I can reach the jackshaft & turn it. Otherwise I'll try turning the crank counterclockwise (as facing the timing cover) a little to try to take up any slack between the crank & jackshaft sprockets. I don't want to turn the crank too far & risk valves touching pistons.
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Something isn’t right for sure. With the tension bolt removed, you should have enough slack. Are you doing all this with the engine still in place?
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Yes, the engine is in the car.
I did remove the tensioner sprocket assy & checked the jackshaft, & it turned easily, so I took up any slack there. I neglected to mention that I was installing new adjustable cam sprockets from RD.
After I reinstalled the tensioner sprocket assy, I still couldn't quite get the inlet sprocket on, so I reverted to the original sprockets and mounted both. At the moment it looks like I may need to move the inlet sprocket one tooth to take up slack between the two cam sprockets.
I wanted to use the adjustable sprockets to dial the timing marks in to match the camshaft timing more accurately after tensioning the chain, but so much for that. The adjustable sprockets are identical, with the timing mark between two teeth, unlike the originals which are half a tooth different between inlet & exhaust, as mentioned in previous forum threads.
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The timing marks on the cams are not “spot-on”. You use adjustable sprockets in conjunction with dial gauges, a degree wheel, and proper cam specs to set up the cams exactly. Generally xx degrees at 1mm of lift. Had to do that on Maserati engines back in the day.