New NB F-cam in NA8

As we already explained before, the new F-cam is being set up in NA8 and in NB8(Sr-1).
The one in NA8 is HLA adjusted, but there might be some cases when after long-term usage you can hear a tap-tone from the HLA.
In the case of NB the lift amount is big and thanks to the shim at high rpm you can experience more power than in the case of NA.

There is a way to set up the NB F-cam in NA8.

The lift amount of the F-cam for NB is 10mm bigger than in the case of NA and even the max. radius is a little bit bigger, so if we set it up in NA without any adjustment, it might interfere with the valve lifter hole’s edge.

If grinding is necessary to avoid the lifter hole’s and cam lobe’s interference, then during grinding it is necessary to remove metal dust and so we recommend to install it simultaneously with the head’s O/H.

The lift amount of the F-cam for NB is 10mm bigger than in the case of NA and when setting it up in NA there might be cases when grinding of the cam’s lobe becomes necessary.

NA8C genuine cam left: INTAKE / right: EXHAUST

Profile of the NA8C genuine cam
IN 8.1mm lift / max. radius 26.1mm
EX 8.6mm lift / max. radius 26.6mm

The F-cam for NB8
IN/EX 10mm lift / max.radius 26.5mm
According to these data the interference on the EX side can be avoided, but on the IN side there is the possibility of about 0.1mm~0.4mm interference. However, thanks to the clearance there is high possibility of installing the cam without any modifications.

The advantage of installing the cam in NA8:
1. we can get better torque and power thanks to the 10mm lift amount
2. thanks to the shim there is a feeling of safety at high rpm

Of course it is possible to use the NB lifter set in NA, however if we use hydraulic lock, that alternates the HLA and we can save more money.
The hydraulic lock is being used instead of the plunger that was removed from the HLA and it is possible to operate it as an inner shim.

If you prefer weight reduction around the valve, we recommend the NB lifter and cap shim.
But if you prefer cost saving, we recommend the alternated HLA (hydraulic lock) for NA.

Alternated HLA – hydraulic lock
We pulled out the plunger from the HLA center body’s inside and inserted the clearance collar instead. (dark grey).

NB8C (early model Sr-1) F-cam for BP

Duration Lift amount HLA Base diameter
IN 252° 10.0mm Special lifter needed 33mm
EX 256° 10.0mm Special lifter needed 33mm

F-cam Intake New Version for Solid (w/o VVT)

Special solid lifter 16pcs set

Special cap shim

The cap shim size is set from 2.65 to 3.65mm (every 0.05mm).
16pcs are needed for one cam.


Maruha Motors Co., Ltd.
Ushizuma 2095-6, Aoi-Ward
421- 2106 Shizuoka city, Shizuoka prefecture
TEL: 0081-54-294-0076
FAX: 0081-54-294-1312