Adj Camshaft Pulley & New Cam Belt

[lwells]

Gary,

What's your feelings on aftermarket timing/cam belts?

I notice there is a bit of a fad in getting belts that are X times stronger than the OEM for considerably more $ than the OEM. Given your belt seemed to have stretch a little, do you think one of the stronger aftermarket jobbies is a worthwhile investment.

Lucien.

[Sydneykid]

Gary,

What's your feelings on aftermarket timing/cam belts?  

I notice there is a bit of a fad in getting belts that are X times stronger than the OEM for considerably more $ than the OEM.  Given your belt seemed to have stretch a little, do you think one of the stronger aftermarket jobbies is a worthwhile investment.

Lucien.

I am not a fan of spending money unless there is a benefit and I simply don't see any benefit in spending my money on a stronger belt when I have zero evidence that says I need a stronger belt. The stretch in the standard belt was minimal and it was 8 years and 105,000k's old. There were no real signs of distress, I am sure that belt would have lasted much longer. That's durability handled, for performance it would be better to go for an adjustable camshaft pulley so I can change the exhaust camshaft timing to compensate for any minor belt stretch over its life. Or simply change the belt more often.

If I had a 3 bar, 10,000 rpm engine with mega valve spring rates, then maybe I could justify it. But even then I am not so sure.

[tikki169]

OOOO the memories. Wish this thread had been up a few monmths ago, would have made life so much easier.

I hade to replace the cambelt (and a few valves) after the cambelt snapped. The guy I bought the car from had the cambelt changed 2000km before I bought the car (family friend owned the car so I'm pretty sure on its hidtory) but the guys placed a washer behind the tensioner pully making it run at a slight angle, this angle was enough to slightly push the belt off and it was running against the cam cover and eventually shaved the belt to half it's origional thickness and then it snapped while doing just over 5000 RPM.

Just be sure when you put it all back together that the right washers go in the right place. Follow this guid by SK and you can't go wrong on the cambelt change. O and def get the harmonic balance puller. I did it without this and it's not an easy task and I managed to remove a few layers of skin from several knuckels getting it off.

[mabru]

Outstanding post, nice pics

[mabru]

I'm not trying to threadjack but I have a timing issue that is drving me nuts. If all timing marks are dead on, what whould cause a light to read high advance off the number 1 plug (measured with a high tension lead)? The CAS is centered and three different timing lights have been used to check against one another but they all come up with approx 29-30 btdc. It's reading in the 30 degree range at idle and the car feels like it's lost a bit of power at WOT but feels ok at part throttle. I'm pretty sure I'm not screwing anything up with the timing measurement and this is the first time I've ever heard of this on an RB.

[Sydneykid]

I'm not trying to threadjack but I have a timing issue that is drving me nuts. If all timing marks are dead on, what whould cause a light to read high advance off the number 1 plug (measured with a high tension lead)?  The CAS is centered and three different timing lights have been used to check against one another but they all come up with approx 29-30 btdc.  It's reading in the 30 degree range at idle and the car feels like it's lost a bit of power at WOT but feels ok at part throttle.  I'm pretty sure I'm not screwing anything up with the timing measurement and this is the first time I've ever heard of this on an RB.

After I put the new belt on, the Stagea was up around 25 degrees, about 1/2 a retaining bolt thickness (~3mm) clockwise rotation of the CAS fixed that. I will leave it for a few days and then check it again, just to be sure:cheers:

[Sydneykid]

Ok, after driving it around for 2 weeks now its time to try some adjustments of the exhaust camshaft timing. I figured I would try 4 degrees retarded to start with, as it is the most common setting;

The first job is to remove the airfliter snorkel and the CAS

Then remove the top cambelt cover

Then the alloy CAS mount has to be removed to enable access to the adjustable pulley slide retaining bolts;

Undo the slide retaining bolts and rotate the camshaft (and the inner portion of the pulley) 2 markings (1 marking = 2 degrees crankshaft as it states on the pulley)

Then tighten the slide retaining bolts, I will loctite them when I am sure that I have the right setting. Then replace the CAS mount, the cambelt cover and the CAS and check the timing. Small adjustment required to advance the ignition timing to compensate for the 4 degrees that I retarded the exhaust camshaft. Rotate the CAS anticlovkwise to advance the ignition timing.

I will drive it around for few days and get a feel for what it is like at that setting. I may then try 3 degrees and 5 degrees just to see which feels better. Then I will stick it on the dyno and see whether my selection is in fact the best.

Hope that was of some help and happy camshaft timing adjusting

Edited June 15, 2006 by Sydneykid

[Driver]

I put mine on today

Took me about 1hr as ive never done it before.

sorry not a stagea tho

[Blk33]

Hi SK,

What is the theory behind retarding the cam shaft timing?

Where are you looking for power increases, low, mid high RPM?

Cheers

Rob

[Sydneykid]

Hi SK,

What is the theory behind retarding the cam shaft timing?

Where are you looking for power increases, low, mid high RPM?

Cheers

Rob

Hi Rob, by retarding the exhaust camshaft timing I am aiming for more mid range, but I can get a bit of top end as well. There is also some faster spooling to gained as well. What it achieves is more complete combustion, before the exhaust valves open. Plus you get slightly higher combustion pressure, for more torque.

You don't get something for nothing though, it also means you get less overlap, the inlet valve isn't open at the same time as the exhaust valve for as long. This means the incoming inlet charge (air and fuel) doesn't help push the exhaust out. This is why it works well with a bit of extra boost (above standard) as that offsets the shorter "push" time.

It's not quite a win/win, but there isn't much downside:cheers:

[Blk33]

Hi Rob, by retarding the exhaust camshaft timing I am aiming for more mid range, but I can get a bit of top end as well.  There is also some faster spooling to gained as well.  What it achieves is more complete combustion, before the exhaust valves open.  Plus you get slightly higher combustion pressure, for more torque.

You don't get something for nothing though, it also means you get less overlap, the inlet valve isn't open at the same time as the exhaust valve for as long.  This means the incoming inlet charge (air and fuel) doesn't help push the exhaust out.  This is why it works well with a bit of extra boost (above standard) as that offsets the shorter "push" time.

It's not quite a win/win, but there isn't much downside:cheers:

I look forward to your dyno runs later.

I like your new pit crew, not your daughters are they?

Cheers

[Sydneykid]

Several things I have noticed since doing the cambelt and adjusting the exhaust camshaft timing;

1. The automatic ECU has 20 degrees as the base timing, not 15 degrees like a manual.

2. There is a lot of parralax error on the timing marks, the marker on the cambelt cover is a long way up and back from the marking on the crankshaft pulley. Take a look at the workshop manual drawing in my early post and you can see the potential for parralax error.

3. Because of #2 above, you have to have the timing light and your eyes aligned and over to the right (looking at the engine). If you look straight down from the centre of the radiator, you get a 5 degree error (ie; 15 degrees looks like 20 degrees). So I had to remove the airfliter snorkel to get my eyes over far enough to eliminate the parralax error.

4. Using the loop wire on the ignitor circuit means the timing light flashes for each cylinder firing (all 6), I was used to only #1 cylinder triggering the timing light. So you get lots of flashes very close together, even at idle.

Hope that is of some help:cheers:

[Bass Junky]

A tuner friend of mine told me that he doesn't trust the loop at the back of the engine bay, says it can be a few degrees out.

Your thoughts?

[Sydneykid]

A tuner friend of mine told me that he doesn't trust the loop at the back of the engine bay, says it can be a few degrees out.

Your thoughts?

I haven't tried it on the Stagea, which may be different due to it having the ignitors in the coils, but the R32's don't show any difference. I have used the wire up #1 coil trick on them and it's the same as the loop. Well as good as my eyes can tell anyway.

[Col-GTSX]

Its an electrical circuit so attach it anywhere its like lightning....

I had a guy say that in class at tafe one day and the teacher (very respected) answered and said "prove it". We ended up doing a test on a 1500m (on a roll) piece of 22 gadge wire and it couldnt be timed.... Even at 1000rpm the and a 1 metre piece of wire you arent gonna have a problem.... All you need to worry about is as syd said is paralaxx error, this is quite common. It is talked about a Tafe all the time..... Its like a golden rule.....

So question for you syd... How did you go with the settings....

1. What did you end up with for hks timing setting vs. overall ign timing???

2. Did you bother replacing the idler bearing???

Im gonna do the water pump cause its cheap and easy so i may as well ($69) But i may try 3 degres i reckon and advance the ignightion timing about 2 degres.... Thats what i reckon...

[Sydneykid]

Its an electrical circuit so attach it anywhere its like lightning....

I had a guy say that in class at tafe one day and the teacher (very respected) answered and said "prove it". We ended up doing a test on a 1500m (on a roll) piece of 22 gadge wire and it couldnt be timed.... Even at 1000rpm the and a 1 metre piece of wire you arent gonna have a problem.... All you need to worry about is as syd said is paralaxx error, this is quite common. It is talked about a Tafe all the time..... Its like a golden rule.....

So question for you syd... How did you go with the settings....

1. What did you end up with for hks timing setting vs. overall ign timing???

2. Did you bother replacing the idler bearing???

Im gonna do the water pump cause its cheap and easy so i may as well ($69) But i may try 3 degres i reckon and advance the ignightion timing about 2 degres.... Thats what i reckon...

1. The exhaust camshaft timing is at 4 degrees retarded, it feels OK but no dyno time yet. Initially I reset the ignition timing to the standard (15 degrees BTDC), but it felt a little flat around 3,000 to 3,500 rpm. So I advanced it to 20 BTDC, and it feels pretty good. Dyno will tell.

2. I checked everything, water pump, alternator bearings, power steering pump bearings, idler, tensioner and even the a/c compressor bearings. Everything was PERFECT, so why the hell would I change anything? And risk infant mortality? Nope, stick with the tested and proven product.

[Bass Junky]

Anybody trying this cm adjustment want to try the inlet cam adjustment as well?

I've got some adjustment rings which you can try.

PM me for details.

[Col-GTSX]

Well previous tests show that with the variable inlet cam that there are no advantages on an rb25set. So no one i know has ever bothered doing one on the inlet cam.

I do know one guy who did it, only cause he wanted a pretty purple HKS timing gear showing through his nice clear timing case covering.... But yeah each time they played with it on the dyno it had worse results that at 0 degres (standard setting)....

So what im trying to say is there is no point....

[Bass Junky]

I thought that it wasn't done much because you had to remove the VVT solenoid to do it, thus loosing the effect of the VVT. Higher grunt down low and up high.

This wheel makes it possible to try the adjustment without removing the VVT system.

[Col-GTSX]

True.... But the retarded timing on the inlet cam should be left up to the ecu and the vvt to do. If you start messing with the standard timing and the exhaust timing this is enough. Little lone messing with the already variable inlet cam.....

You would have to disable vvt to use it properly. This would be fine if all you wanted was power or torque... VVT allows the car to have both....