Cam Belt / Valve timing help required

I have changed the cam belt on my VHPD engine but got a bit lost with the timing marks. The crank pulley is a light weight alloy one with no timing marks, I can find TDC with a rod down the spark plug hole but what should the marks on the piper cam wheels be? There appears to be two pen marks per wheel and a venier scale on each wheel should any of these line up when number 1 is at TDC?

Align the crank at 90BTDC with number 1 piston rising, then align the vernier sprockets as per the details here how to fit verniers


Dave, Thanks
Looks like ive buGGered it up, what would be the lift at TDC for each of the cams with the standard Lotus camshaft

Without the 190 kit

inlet 90 thou
exhaust 115-120 thou

These will of course vary due to slack/innacuracy/variances in the belt train components.

They should be set to

130 thou inlet
115 thou exhaust

with the verniers.


I dont understand the 90BTDC mark in the LOTUS manual appears to be 45ATDC, so last night I used a dial gauge and found 1/2 way up on the compression stroke and set the cams that way, all now appears OK. Have I misread the manual or am I as thick as my wife says I am !!
Cheers Simon

You’ve misread the manual, it’s a different marker on the front pulley for the 90BTDC, it’s discrete from the TDC marker, that’s why you are confused…

90BTDC is when all the pistons are level (incidentally due to crank/rod geometry they are more than halfway down the bore…) and number one piston is rising.

Runs like a dream thanks

Runs like a dream thanks

Does that mean you’re imagining it, then?

Seriously, matey, well done