OK, speaking to my mech yesterday (got my SC fixed, will be saying goodbye soon ) about getting the inlet cam retimed and was trying describe it to him in my spazmod way…
But basically WHY do you need to buy verniers or the Lotus inlet cam? can you not simply line up the pullies and advance the inlet cam with a dial guage then stick it back together?
What’s the standard offset on the inlet cam? Obviously you’re not advancing it 110 deg from it’s current pos I did see something on Dave Adrews site about doing it with different dowels and what not
So basically just seeing wht I should spend �200 on vernier pullies for one timing change IYSWIM…
TIA,
Mark
One of the other will tell you in greater depth (Andy, mike?), but I thought without them they could only be adjusted all at the same time, which is no good if only one is out.
Ian
Well once the cam belt is off / slackened you can turn the cam’s seperatly then retension the belt… Obviously after just slowly turning the crank and not just firing her up
You can only move the current cams by jumping a tooth, however this is far too much of a change to the cam timing, each tooth i think works out at a 16 degree move.
If you have ever put a dial guage on the cam follower the tinyist of movement on the cam causes masses of change to the lift. !!
You dont need to spend �200, verniers are available now at �50 each or the trial and error way of making off-set dowels, personally verniers are much easier to work with
Remark
I always understood that Verniers merely make the job a whole lot easier but any technician worth his/her salt and armed with the correct dial guages/dowels etc (which any technician worth his/her salt will have and/or make) can do this without the verniers… after all its only that they have accurate calibration marks on em… ain’t it? but that’s not the only way to time a camshaft…
What’s the standard offset on the inlet cam? Obviously you’re not advancing it 110 deg from it’s current pos I did see something on Dave Adrews site about doing it with different dowels and what not
RemarkLima
I hope you mean 101degree??.. . The timing is advanced 4degrees from the normal 105degrees ATDC, but you need an ECU that can be told this… otherwise you will get detonation…
so if a tooth is 16degrees (i take Phils word for that) then you need to advance by 1/4 of a tooth… so… what’s so difficult about that?? all that woosin around with verniers… for �200… pah !!
You can only move the current cams by jumping a tooth, however this is far too much of a change to the cam timing, each tooth i think works out at a 16 degree move.
Phil
Why can you only move a whole tooth at a time? can’t you use dial guage and dowels and mark up standard pulleys to move the 4degrees that RL is looking for??
Sorry for not making it clearer but that answer was in response to
But basically WHY do you need to buy verniers or the Lotus inlet cam? can you not simply line up the pullies and advance the inlet cam with a dial guage then stick it back together?
Yes you can use a dowel on the stand pulley to move it.
The Lotus 190 upgrade consists of a pulley exactly like the old one, except for another lobe cut into it for the dowell…
As regards just loosening and tightening until you get the right numbers, the problem is that when you tighten up the central bolt, everything moves…
Then you check the timings and they are wrong…
I understood that the reason you can’t do half a tooth is that the belt tooth-holes are fixed, and you need to LOCK the two pulleys in position before you start messing around, or you end up with a mismatch, and a chewed timing belt, followed very quickly by valves and pistons having illicit affairs
The verniers allow you to lock off the two pulleys, nice and safely, and then turn the actual camshaft within the pulley without moving the outer teeth… Then when the timings look good, you tighten up the four allen bolts, and bob’s your Pesky…
Ah excellent, thanks for that guys
I understand about the only being able to move a tooth at a time, makes sense…
And sorry yes did mean 101 I’ve got the Emerald ECU installed now and it’s sooooooooo much better already, just may as well get full power IYSWIM
So no worries about getting the ECU to understand the advance… So 4 deg advanced of the standard 105 deg, cool ta muchly yet again