Degreeing a Standard CAM - 1.6 GTI

[ALEX 98 1 Cars]

Hi. I'm looking to degree my standard 1.6 Gti CAM (Xu5JA) Part No. 0801 N4. with an adjustable pulley.

Reasons for this is because I've taken a significant amount off the head to get to good metal (1mm actually), this will retard the timing on the stock pulley.

I need the standard Cam specs, but struggling to find them.

I've used this in the past to a 3d Printed disk Degree Wheel Templates Valve Timing - Inch

 

I need the info. I'm not sure that in the photo is correct - (I can't remember where I got it from)

 

 

 

[welshpug 1,710]

i found this https://www.aussiefrogs.com/forum/index.php?threads/205-gti-vs-si-camshaft.89693/

Edited January 12 by welshpug

[ALEX 98 1 Cars]

I found this info using Google AI. (Though from experience, if found information using AI often wrong) 

 

Total Valve Lift    11.5 mm (approx)
Inlet Duration    230° (measured at specific lift points)
Exhaust Duration    223° (measured at specific lift points)
Inlet Opens    8° Before Top Dead Center (BTDC)
Inlet Closes    42° After Bottom Dead Center (ABDC)
Exhaust Opens    40.5° Before Bottom Dead Center (BBDC)
Exhaust Closes    2.5° After Top Dead Center (ATDC)

 

Also would the measurements be at 1mm valve lift or 0.1mm?

[ALEX 98 1 Cars]

Something I just realised , When measuring camshaft as fitted using a DTI on the lash cap, I'm assuming I need remove the valve clearance first . Ie fit a thicker shim under No1 Inlet and exhaust. 

 

Tip for anyone who finds this: The DTI (well the one's I've seen) use an M3 thread you can screw extensions into to reach past the cam. I found an old mountain bike spoke cut down screws in perfectly for this.  Saves finding a welding rod and having to thread the end.

 

 

 

 

[welshpug 1,710]

you don't need to remove the lash, you don't run the engine with 0 clearance ...

 

spokes are 2mm with a 56 Tpi  (yes, very odd, but so are a lot of bike threads...)

Edited January 12 by welshpug

[ALEX 98 1 Cars]

I did some measuring though my set up is a little sketch, but I'm confident I got some fairly accurate readings.

The inlet cam (with 0.006" valve clearance). measured at 0.1mm lift intervals measures:

Inlet opens 14°BTDC

Inlet closes 67°ABDC

= 261° Duration.

 

It looks like the figures above (230° duration) are a little on the low side.  Unless that's measured at 1mm lift?

 

I did measure mine at 1mm lift and I was getting:

Inlet Open 8° ATDC

Inlet Closes 45°ABDC

= 217° Duration.

 

I could do with some more info on this cam. 

There's a single cream/white band to the right of the inlet lobe for cylinder no 3.

 

[Tom Fenton 1,620]

The way I would do this is pin the cam on the standard pulley, then measure an open valve position, any valve that’s open will do. Remove the standard pulley and fit the vernier pulley. With the belt on and crank set at the timing position measure the same valve lift, then adjust the cam pulley to put it back where it was when the cam was pinned. You’ve then restored it to factory timing. 

[ALEX 98 1 Cars]

41 minutes ago, Tom Fenton said:

The way I would do this is pin the cam on the standard pulley, then measure an open valve position, any valve that’s open will do. Remove the standard pulley and fit the vernier pulley. With the belt on and crank set at the timing position measure the same valve lift, then adjust the cam pulley to put it back where it was when the cam was pinned. You’ve then restored it to factory timing. 

I like your thinking. I think that would work in theory , but the pins and holes aren't exactly to a tolerance. I'm guessing they only need to be within a tooth for OEM belt fitting.

I'm planning of using the measured arc length on the cam pulley. I know the skim amount is 0.8mm, which pushes the belt back. that equates to only 0.73° on the od of the camshaft pulley. (1.46° on the crank).

I can't see me doing much harm with 1°of advance on the camshaft pulley. I might even increase it further for more low down torque when I get it back on the road.

 

[ALEX 98 1 Cars]

For anyone looking into degreeing their cam. I found this really useful as you can add valve timings for the cam you are fitting.

Custom Degree wheel generator link

 

The KentCam degree wheel that came with the Adjustable pulley is very generic. It's also difficult to adjust without effecting the crank position as you have to loosen the crank bolt. 

I designed a 3d print that attaches to the pulley washer OD with grub screws. I'll dig out the STL and put it on Thingiverse. 

 

Edited January 14 by ALEX

[ALEX 98 1 Cars]

My set up is a 1.6 B6E engine with a 0.8mm skim and standard 1.6 Gti cam (Second hand cam - so standard to as told).

Excessive head skimming retards the valve timing, from my measurements this is approx 1° per 1mm of skim on the Cam pulley (2° per 1mm on the Crank)

Probably not much to make a notable difference to bother (maybe at a 2mm skim ) , but I had an adjustable Pulley already, so why not.

 

For records and to help others :

 

Before adjustment set at 0°:

Measured valve timing (Inlet at 0.1mm) 

Inlet Open @ 14° BTDC

Inlet closes  @67° ABDC

261 inlet duration.

 

Cam timing set at 1° of advance.

Measured valve timing (Inlet at 0.1mm) 

Inlet Open @ 16° BTDC

Inlet closes  @65° ABDC

261 inlet duration.

 

 

[petert 630]

On 1/13/2026 at 12:42 AM, ALEX said:

Something I just realised , When measuring camshaft as fitted using a DTI on the lash cap, I'm assuming I need remove the valve clearance first . Ie fit a thicker shim under No1 Inlet and exhaust. 

 

 

 

 

There is no need to remove the shim. You just need to allow for the lash when doing the timing. And then, only when using the lift at TDC method.

 

For example, the cam setup specified 0.070" lift at TDC to obtain a 112º lobe centreline (LCL). If you had 0.008" of lash on the inlet, you would subtract that.

eg 0.070"- 0.008" = 0.062".

ie you'd position the cam at 0.062" at TDC.

 

As you don't have a TDC figure, I would use the LCL method to time it. The oem position is probably 112º. Time it at that initially. Then check you you have a sensible lift @ TDC figure as well. It will most likely be in the range 0.050"-0.060". 

 

If you want bit more bottom end, try advancing to 110º. It won't be any less than that for an oem cam.

 

Google how to do the LCL method if you're unsure. There are plenty of videos.

 

I'm not sure what you have done is particularly accurate. You really need to use one the two methods above.

 

For reference, a skim of 1mm requires the inlet cam to be advanced approx. 4º (crank).

Edited January 19 by petert

[pug_ham 245 3 Cars]

When I set up a friends old GTI that had a skimmed head on, I did pretty much what @Tom Fenton suggests.

 

I fitted the crank timing pin & without the belt on, turned the cam pulley to align the timing pin hole.

 

I marked the cam position on #1 cylinder & using a DTI on the bucket with a vernier pulley on set it to the same point.

 

g

[SRDT 226]

If you had a reliable way to keep the cam in place without the pulley you could even ditch the mesuring part.

Just like on the stock XU10J4R you tension the belt before fully tightening the adjustable pulley screws.

[ALEX 98 1 Cars]

On 1/19/2026 at 8:10 PM, petert said:

There is no need to remove the shim. You just need to allow for the lash when doing the timing. And then, only when using the lift at TDC method.

 

For example, the cam setup specified 0.070" lift at TDC to obtain a 112º lobe centreline (LCL). If you had 0.008" of lash on the inlet, you would subtract that.

eg 0.070"- 0.008" = 0.062".

ie you'd position the cam at 0.062" at TDC.

 

As you don't have a TDC figure, I would use the LCL method to time it. The oem position is probably 112º. Time it at that initially. Then check you you have a sensible lift @ TDC figure as well. It will most likely be in the range 0.050"-0.060". 

 

If you want bit more bottom end, try advancing to 110º. It won't be any less than that for an oem cam.

 

Google how to do the LCL method if you're unsure. There are plenty of videos.

 

I'm not sure what you have done is particularly accurate. You really need to use one the two methods above.

 

For reference, a skim of 1mm requires the inlet cam to be advanced approx. 4º (crank).

Thanks for the input. The LCL method would be the way forward, but a known LCL would be ideal. It's all together now though I may return to this in the future. Maybe a Fast road Cam? 

My thinking is that I can't be worse off than the stock pulley with only 1° (2°crank) advance to take into account of my excessive skim.

 

(For records and clear contradiction above. The head was skimmed by 1mm, but a 0.2mm thicker gasket was used. = 0.8mm Skim)

 

From reading up on tuning on this engine, (Puma racing ) blast from the past. He mentions the thicker gaskets are not worth fitting and suggests a 1mm skim to improve performance.

He did a gas flowed head for my 1.9 Gti with a 1mm skim and I remember it Pinking quite badly even with 98Ron.  The compromise to stop it from pinking was to retard it on the dizzy though performance dropped off a cliff. 

I sold the 1.9 back in 2012.

 

 

 

Edited February 6 by ALEX