Aftermarket Camshaft Timing?

[matt dunn]

Ok I've been checking the camshaft timing on my 20V turbo motor because when I put It back together last time ( the day before race day) I was short of time and just aligned it up on the standard timing marks.
It has aftermarket camshafts which I believe did not use the VVT and used standard camshaft pulleys.
I noticed when I assembled it that the standard timing marks had been painted white, but one tooth anticlockwise someone had centre punched and painted what looked like a new mark.
I was unsure if that was where it was meant to be and the last owner of the car ( and engine ) is not much help.
Anyway I emailed away the place that did the cams and this is what is got as a reply.

Hi Matt - tappets are .010" on both cams - set intake at 110 degs ATDC - set exhaust at 110 degs BTDC

Well the tappet setting were all wrong as it threw out the shims from under the buckets, ( twice, on two different cylinders ??)
and so we have redone our own settings.

I have roughly checked the cam timing myself and I presume that 110 degs is the lobe centres as it's the only figure that's even close.
I will say now that my measurements aren't 100% accurate but I believe them to be within 5-10 deg either way but I will recheck them tomorrow night when I get a dial gauge.
Now I am only guessing the lobe centres are between the opening and closing 1/2 way and this gives me the result that the Exh cam is out by 8 deg which is within my measuring allowance but the Inlet cam is retarded by 40 DEGREE'S!!!
Now if i move the belt onto the handmade marks and now assume the VVT is needed and include the 30 deg it has that gives me the 40 deg that I think is missing.

All seems to make sense,

but how can it make 204kw at the wheels on the dyno with the inlet cam retarded 40 degrees???

Anyone on here done precision dialling of cams before or know exactly how to do it as this makes me believe I am doing something wrong.


Matt

[10k 20v]

hi matt.
i've done precision timing on my engines and the only way i managed to get it right was by making some vernier wheels for the cams. (20v)
the aftermarket cams i had ground where so far off on the stock marks (including vvt phasing) the only way to get them close was to simply dial them in using the vernier wheels.
110 would definatly be the lobe centres. intake atdc and exhaust btdc

if i had the dyno charts in front of me when i tried a run using the vvt (off and on) i'd tell you the exact amount but from memory it was around 10-15kw of peak power but the midrange suffered hugely

dosen't suprise me at all to hear the cleance were set wrong by someone else. been there

[matt dunn]

OK, checked it again now I have a dial gauge to check it all and got some different results.

I checked up and found out that VVT is not meant to be used and I have to weld the pulley solid.

And the timing was out but only by 20 deg not 40.

There's 36 teeth on the cam wheel so 10 deg per tooth,
but forgot that's cam degree's so double it for actual degree's.

So in the end with the pulley made solid and the cam 1 tooth from the factory marks the cam is now dialled in 100%.