×

Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

4G63 adjustable vernier cam pulley gear

General Tuning Discussion

Forum Posts

Courses

Blog

Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads

Author
770 Views

I've just changed out my old HKS cam pulley for a new AEM unit and I decided to adjust it by 1 degree to [potentially] improve response a bit lower down the rev range (I may put it back to 0 which is where the HKS one was set to). I will also add that I would have loved to time the camshaft in correctly but I can't find the timing card info for Cosworth M2 Evo 9 cams online. May be a placebo but it seems to rev a bit better without load following this adjustment.

This has left me with 2 questions:

1) is this likely to effect the timing offset as the sync tooth is on the end of this camshaft. I presume not, but nice to know from those more experienced than I.

2) Do I need to loctite the cam pulley adjuster bolts? I have torqued them to spec and run the car up. The main bolt is now ARP and the instructions with that bolt didn't require it and I don't recall the workshop manual indicating loctite either.

Attached Files
  • 9CC7D9EB-4CA2-4A17-8AC9-EAC0473A3456.jpeg
  • Attachments may only be downloaded by paid Gold members. Read more about becoming a Gold member here.

Normally, the camshaft signal resets the ECU so that the next time the crank position signal comes up it will count for TDC firing the next time it's at TDC, rather than overlap. So you would be correct - I think.

As you've torqued the vernier (?) bolts, you shouldn't need a thread-lock but, if you've determined where you wan the timing, and are unlikely to want to change it, you could lock each one in turn - leave the other four in place to maintain the timing as you do them. Personally, I probably wouldn't unless I had a real concern, and I were using a cover that could trap any bolt that came loose and potentially spit it into the timing belt. Anyone?

Thanks for the reply. Really great point about the overlap, I hadn't even considered that. I will check that with PC Link when I get 5 mins. It did seem to rev a bit quicker/ more freely but that could 100% be a placebo. If I get time I may adjust it back to 0 to see if I can see any change.

The pulley bolts are torqued and you're quite right in what you're saying about doing 1 any a time. I guess my query were more from the position of "what if I want/ need to adjust them" later or as a process of tuning more generally as surely locking them would defeat the object as you may need to move them whilst on the Dyno/ road? Upon reflection, for my purposes I will most likely put some medium loctite on them all but I was curious on others' opinion and experience.

This is probably granny>eggs, but just in case...

To clarify, in context "overlap" meant one complete engine revolution from what would have been firing. ie. TDC (firing - when the mixture has just been ignited) > combustion > BDC > exhaust > TDC (overlap - exhaust closing and intake opening) > induction > BDC > compression > TDC (firing - ditto).

The crank pickup only knows the crank position, but not whether it's on the combustion/exhaust or the induction/compression revolution. The camshaft(s) rotate(s) at half engine speed, so by using a sensor there that registers when it is at a specific point of rotation, the ECU will use that to reference what revolution the crankshaft is on, ensuring the ignition and injectors fire on the correct revolution.

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?