Why different cam gears?
 

This is a 2004 msm. Why are the cam gears different? The one on exhaust side is standard. What's the other one? Is it an msm thing?

It has timing "teeth" for the CAS

Is it on right? Or does "I" go up?

On does it matter?

Another question.... This msm gear shown here on intake swappable with NA gears?

In other words they are the same.

It looks like it is on right as best as I can tell. No you cannot swap a na intake cam gear onto the msm. The NA cams do not have the marks for the crank sensor. You could swap intake cam gears from a 99/00.

Ok. Got ya.

Feel stupid, done 1000 timing belts and never seen this configuration before. 1st msm tho.

Interesting that the MSM only has CAS nubs on the intake gear, the NB1s have it on both. Unused on the exhaust side, but it's the same part.

https://www.miataturbo.net/attachmen...ine=1454483413

I'd guess the Toda NB gear should work. I put one on my car -- saw basically no effect from it on the dyno though.

https://www.miataturbo.net/attachmen...ine=1454483413

--Ian

Did you actually play with the settings?

The MSM intake cam gear is different from the NB1 because the timing is different. It's more than appearance.

Nope, it's the same except the timing nubs. Matched them up last night, identical.

The MSM and NB1 heads are the same.

No, I'm sure he just stuck it on and then spent money on the dyno and didn't dial it in at all.

The one on the left is NB1 the one on the right is NA. NB1 put the cam sensor on the front of the head and used nubs on the cam gear for it to sense. NA cam gears are a bit lighter but if you are using the sensor on the front of the cam cover you need a gear with the tabs on it. NB2 put the sensor in the top of the cam cover and reads nubs on the intake cam but still uses an NB1 cam gear on the exhaust side.

I ran the cam gear through its range on the dyno (-10, -5, 0, +5, +10), one way it lost spool but had no measurable high-end gains, the other way did basically nothing, so I set it back to zero and it's remained there.

Looking at the MSM photo more closely, it does appear that the nubs are in slightly different positions than on the NB1 gear. NB1 has the single nub and double nub 180 degrees opposite each other, while on the MSM looks like one of them is offset slightly. I wonder if the factory ECU cares? I'm pretty sure the megasquirt isn't going to, the non-VVT code is just looking for cam sensor pulses to occur between crank sensor pulses, and if the cam is off by 10 or 20 degrees it doesn't care.

--Ian

Hmm, I wonder if it's because it's just the intake cam? I have heard a few folks (on non BP platforms) have retarded cam timing in the lower RPM's to increase spool. I have also heard advancing both intake and exhaust causes a shift of the power to the higher RPM's. I've mainly heard this on VVT-style engine

Again it's all hearsay. You are actually the first I've heard that has adjustable cam gears on a BP engine.

According to Jeremy @ FM, the exhaust cam does almost nothing, which is why I only bought one. The intake cam is supposed to trade off between low end spool and high end power, but all it seemed to do on mine was hurt spool without adding any power.

Next time I have it apart I may revert the cam gear back to stock and sell the Toda, dunno.

--Ian

Get a VVT head and have best of both worlds