cam timing with a belt drive
Turbo Mini Forums

There are two notches on the pulleys, but they don't look very accurate!

How can I time up my engine using a DTI?
I assume I need a timing disk?
Does any one know the figures for a std cam?

thanks!

Alex

AlexF

?????
alex needing help

look at minispare swebsite, go to articles, KC made an exellent one about cam timing.
and I assume you should use a timing disc, it could be funny without!

I'd suggest 110 ATDC for a standard cam.

Only my opininion though.

Is it the fully adjustable belt drive?

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

only a fool asks for no help.

Even when you are sure you know how to do somthing, if you have not sucessfully completed a job before why not ask other opions, after all no one can say they have nothing more to learn. Thinking about it, even if I did know exactly how to do this job I would probably still ask incase someone has a good tip or trick to make the easier/faster/better.

The question about the timing disk was asking if it was possible just on DTIs alone... I can't find my timing disk at the momoent either LOL

Wil, its adjustable, but only in ther offset key sence!

Alex

AlexF

Ok. Mine is fully the adjustable type and it's a pain in the arse to set up.

copy this photo of a protractor and print it out job's a good one

http://www.lighthousepubl.com/enpg3.html

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

wouarffffffffff!!!!,
an english with french humour, as funny as the timing without timing disc!

seriously,
you absolutely need a good timing disc,
set it at tdc using a dti to find the real/acurate tdc, and don't miss to check that your damper tdc is ok,
then turn you crank clockwise untill your max inlet lift on cyl number one is reached,your dti show that your cam is now let the valve closing, check your timing disc degree ( mety turbo have a max lift at 106?), then still turn your engine clockwise untill your inlet is at 1 mm before the last max lift, check the timing and rich the same level but after the max lift, check the degree on your timing wheel, make the croos point between these numbers, ( ex 1mm before max lift=100? ; one mm after max lift=110?, max lift is 110+100/2=105? so you need a 1 ? key to set it at 106?...

i forgetted , a paper reproducing a timing wheel can be printed from marcel chichack tdc engineering

http://www.telusplanet.net/%7Echichm/tech/valvepolar.pdf

Alex,
Establish a tdc with your DTI. The only figure you need is the valve lift at TDC. Turn your camshaft till you get the required valve lift (not cam lift) and jobs a good un.
Moose

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

Thanks moose... anyone know that figure?

Alex

AlexF

110 for a standard cam - as Wil suggested

no not the timing figure... the valve or cam lift figuer...

alex

AlexF

just need max lift though dont you measured with the DTI? Surely thats one for you to figure out?

Or am i missing the point?!

AlexF

huh?

Looking at #1 inlet - wherever full lift (whatever it is) occurs on the cam lobe, this should be 110 degrees AFTER TDC for # 1 cylinder...

ps - It's not too bad timing it in at around 108/109 degrees, as gains can be had (depending on the grind), but don't exceed 110 degrees in any circumstance!

right - back a bit...

Put timing disc on the crank at water pump end.
Put DTI on piston to establish where TDC is "approximately".
Make a pointer (gas welding rods are ideal) and set the disc to zero at the pointer.

Turn engine anticlockwise until the DTI drops by a little over 2.5mm. Now turn engine clockwise until the piston is around 2mm down from tdc, and note this reading on the dti.
Note the reading on the protractor.
Continue turning clockwise until the piston passes TDC and drops to the reading on the DTI where you took the last reading ( around 2mm). Note the reading on the protractor.
Add up the difference in protractor readings (remember one is -20 degrees for example, the other +20 degrees), and divide by 2 to get the average, and this is how much you need to move the pointer by to get true TDC.
Once happy with TDC, continue!

No stick the dti on the #1 inlet pushrod, crank engine over till you see full lift. Zero the DTI.
Turn engine anticlockwise, so you getaround 2.5mm drop, then forwards to 2mm and note the DTI reading. Take the protractor reading, then rotate the crank forwards past peak lift, and until you see the ame reading on the dti. take the protractor measurement.

Take the proractor measurementS (eg 97 and 119 degrees) add together (216 degrees); divide by two (108 degrees) and that is the value your 'full lift' is at.

Note how i always take it 'past' the point where you will take the measurement, then clockwise to the measurement point.
You should never EVER be turning the crank anti-clockwise when in the middle of measuring.
If you get lost, or confused, start again!!!

As a 'safety check' go and check the lift on the other cylinders is about right aswell...

Edited by turbodave16v on 15th Jul, 2004.

somet wrong with the site - the top one is the revised one - ignore the second post - that's my uneddited original!

right I've delete the 2nd thread to stop me getting confused... (got a copy saved if you want it!).

Right better get on with reading it!

aLex

AlexF

Right that makes sence...

I better print out a temporary timing disk, as mine has def walked off somewhere...

Its only really as a check with intalling my new cam drive (belt system) as there is nothing I can do if the timing is out fot the moment!! Well certtainly not before Avon anyway.

Alex

AlexF

Another important thing is to make VERY sure the disc is concentric to the crank... If it has a run-out of just 1mm or so, it equals around 1 degree on a 150mm disc!

The biggest the disc the better!

I can only print A4...

but have worked out I can easily make my own disk on AutoCAD just to make sure its got the figures on I want!

Alex

AlexF