Advancing the cam gears

[nvs_sle]

Hi all,
ive read and been told that holden retarded the engine by 1 tooth or something. Was just wondering how easy it is to advance the cam gears and i wanted to know if someone could tell me how to do it as i dont wanna go messing around with my engine! Also, could you guys just give me like a litle run down of how to advance the cam gears and timing etc,
I just want a little more performance outa my pretty much stock engine!
Cheers

[Don Sutton]

General rule re valve timing:
Advanced valve timing favours low speed running.
Retarded valve timing favours the top end. This applys to single camshaft engines. The retarded timing gives a later closing of the inlet valve which allows for air flow lag at high speed.
I am not familiar with the details of how the timing gear is attached to the camshaft of the Nissan engine (assuming it is the standard VL 6 and not a V8 or re-engined car, but a common method of changing the timing without confusing anyone who needs to service the vehicle is by way of an offset key. An offset key looks like it has partially sheared but moves the gear in relation to the camshaft. If you move the camshaft clockwise while facing it while keeping the gear in the same place you are retarding the valve timing. You can remove the timing belt or chain as the case may be and move the camshaft and sprocket anti clockwise the distance of 1 sprocket tooth to advance the timing or 1 tooth backwards and refit the belt or chain. Some types of engines you cannot go this far as you risk the valve touching the piston at TDC. It's a long time I had anything to do with a VL so I can't remember if they have a belt or chain and in any case when I worked with them they were new and hadn't developed any problems that would have required me to delve into this area.

[Stewart1000]

well it its retarded one tooth, to advance it opne tooth, take off the timing case, using an allen key, remove tension on the tensioner and remove the belt, turn the camshaft 1 tooth anti colckwise. all you really need to do is turn the dizzy, much easier.

[Don Sutton]

well it its retarded one tooth, to advance it opne tooth, take off the timing case, using an allen key, remove tension on the tensioner and remove the belt, turn the camshaft 1 tooth anti colckwise. all you really need to do is turn the dizzy, much easier.

Are we talking about the same thing?
I got the impression that Stewart 1000 was talking about the valve timing and my answer is based on that. The post by nvs_sle appears to be talking about ignition timing. It would be unlikely that a car coming from the factory with the ignition timing out one tooth would run too good if at all.
PS if you changed the valve timing and the distributor is driven off the cam you would have to reset the ignition timing and if the distributor ran out of adjustment to allow correct timing you would need to take the distributor out and retard it if you advanced valve timing or vice versa if you retarded the valve timing.

[mischf]

The first part of what stewart said is correct, take off the belt, move the camshaft and put it back on. I advanced the timing on my VL, i moved it about three teeth though It made a difference at high revs as it moved the power band up a bit, so i was getting good power at 4500, whereas before it used to die at about 3500.

As for moving the dizzy all that will change is the ignition timing ie when the spark goes of. No matter what you do to the dizzy the valves will open and close at the same time. You have to move the cam, or get an adjustable camshaft pulley like on the skylines, you can loosen the pulley and the outer ring with the teeth on it will rotate so you can adjust valve timing that way, better than taking your belt off.

[Stewart1000]

yes but if you apin the dizzy you can get the spark to happen earlier, advancign the ignition timing.

[Marco-EFIVL]

Or do both...

[gungazza]

The first part of what stewart said is correct, take off the belt, move the camshaft and put it back on. I advanced the timing on my VL, i moved it about three teeth though It made a difference at high revs as it moved the power band up a bit, so i was getting good power at 4500, whereas before it used to die at about 3500.

As for moving the dizzy all that will change is the ignition timing ie when the spark goes of. No matter what you do to the dizzy the valves will open and close at the same time. You have to move the cam, or get an adjustable camshaft pulley like on the skylines, you can loosen the pulley and the outer ring with the teeth on it will rotate so you can adjust valve timing that way, better than taking your belt off.

yer i saw a adjustable camsaft pully on ebay

[Stewart1000]

Or do both...

yeah but the problem with doing both is that the dizzy runs off the cam gear, so if you are doing both, it might get a bit tricky because you have to think about where the piston is, when the valves are open and when you want ignition to happen, if you thought about it i'm sure you could figure it out but yeah, for the agerage person, i wouldn't do it

[vt1538]

Your spark will need to stay the same in relation to the piston not the cam. So therefore when you adjust the valve to piston timing you will need to readjust the distributor timing.

[hosedogg]

so when advancing the cam do you move it clockwise or anit-clockwise? and does advancing it improve top end or bottom end? cheers.

[Don Sutton]

so when advancing the cam do you move it clockwise or anit-clockwise? and does advancing it improve top end or bottom end? cheers.

See my bit above repeated below:
General rule re valve timing:
Advanced valve timing favours low speed running.
Retarded valve timing favours the top end. This applys to single camshaft engines. The retarded timing gives a later closing of the inlet valve which allows for air flow lag at high speed.

[greenfoam]

Advancing the cam would be going backwards in my opinion, Maybe this whole theory is upside down and Holden infact allready advanced it? that would make more sense. If you retarded the cam and advanced the timing to make up for the loss in bottom end, then you would be going places