Hello everyone. Been a while since my last desperate post. She has been off road 5 weeks while i have been on holiday and have been Trying to sort problem.
After a Lotus expert suggested the cam timing was out, probably since PO rebuild 4 yrs ago, if you remember when I posted photo it was difficult to tell. Marks appeared to line up but were below level of head casting.
In desperation and unsure whether to alter them or not, I took off head to check it on bench.
This also allowed for a decoke and a couple of noisy tappets to be sorted.
Once on the bench to my disbelief, to line the marks up as in the workshop manual, with the marks level with the head casting, I had to turn the inlet back one tooth and the exhaust forward one tooth.
2 teeth out.
Once the head was rebuilt and back on it was impossible to get all 3 timing marks perfect. In the end after trying every position possible, the best compromise was the two cam pulleys absolutely spot on and the crank pulley approx 7 degrees out. To get the crank dead on TDC meant both cam pulleys were then out and there was not enough in the chain to level them up. Hence the mistake by the previous engine builder.
After checking all by hand I went for broke and built and fired her back up.
Immediately I could tell she was revving completely differently, far more eager and lively. I took her for a blast up the lane and she feels as if she has another 30BHP or so. Big difference, no flattening out, nice growl, no farting through the exhaust, smooth powerband, only the odd misfire.
She is running a bit lumpy because the carbs are now a mile out of balance. That's the next job.
Have retested the compressions with the throttles open and have about 200 across the board.
Thanks to the many people who responded. I feel now I have a fighting chance of getting her running like Chapman intended. No wonder the PO could never get her running right.
I have posted a photo of the timing marks on the bench to compare with the one earlier in this post on the car.
Mark.
Mark.