Caution when removing cam gear cover!!

[GTRgeoff]

Recently I took upon myself to remove the cam gear cover and run without it. The need to see things moving was too strong I suppose but have today made a discovery.....and not good.

When I was remounting the optical timing unit I noticed that the bolts were pushing through too far and would contact the cam gear as it rotated so I put in a couple of spring washers behind the timing unit to stand it off a little.

A mate of mine copied my setup almost exactly, which I noticed a couple of weeks ago when I was checking his cam timing which a quality mechanic had told him was 40 degrees out (wanker), it was spot on. What had occurred was the positive locating piece on the end of the cam had snapped off, meaning a bit of double checking befor refitting the timing unit, and I thought no more of it.

Today, after some annoying surging I replaced the fuel filter, which as usual was full of crap, but there is still a little roughness, a miss, at around 2500 rpm but it changes a little by plus or minus 200 rpm with temperature.

It is so noticeable through the gearstick I was concerned about balance in the engine......but these things don't just go out of balance over a couple of weeks so can that idea.

So anyway the plugs have been replaced, the ignition coils are running at 1.3Kohms of resistance and the fuel filter is new. The malpassi is fitted but not turned up (until tuning with the PFC) so it has no effect and the GTR fuel pump is singing and pumping strong as you can see the hoses flex under the pressure.

I decided to pull out the mechanics stethoscope and have a bit of an explore around the engine...the injectors are tapping away and everything sounds sweet but there is a little miss and it is noticeable at 2500 rpm when standing outside the car from the exhaust outlet. So then I run along the exhaust side and decide to stick it on the timing unit and it is tap tap tapping REAL loud and in time with revs even as the revs lift. Not easy to hear elsewhere but right on the module it is scary.

Now I pulled it off and discovered the same has happened to mine, the locating lug is broken and the faces at each end are shiny from rubbing.

So I think back to something strange that occurs when I fiddle with the timing....the revs pick up when I back off the 3 locking bolts for the timing unit, and drop again when I tighten them.

So I suspect that I have jammed the operating parts together inside the unit, causing the tapping and the change in idle speed. I will have to wait until the roads dry to determine if putting extra spacers in will fix it, or if I need a new timing unit from the wreckers, as in the wet it will just be a wheelspin session (yep it's raining in Melbourne) as the car is mostly making really good power past 3000rpm on stock boost...like just spinning up in second in the dry with over-enthusiastic throttle operation, but sometimes it just goes all sluggish, usually when the engine gets nice and hot after a good 30 mins of driving. But then it can change and goes wham with the power again.

So if you have done the same to your engine, and haven't spaced the timing unit far enough off the mounting bracket, just be cautious until I get to the bottom of this.

I will post back with developments.......

[Sumo]

Thanks for the heads up mate.... So that was just a result of the timing unit not being spaced since there was no cover? No other problems then that?

Sumo

[GTRgeoff]

I had time last night to space it further off (the crank angle sensor (CAS)) and run the car and the bad tap has gone but I had the sensor off by 1 tooth which retarded it bad so I pulled full advance on the CAS but it was pretty sluggish. Also the rpm drop when tightening the retainer bolts has stopped. I'll get back with more once I have fixed this problem.

[Sumo]

hehehe, sounds like fun to say the least

[GunMetalR33]

How much do the clear cam gear covers cost, might be a better option if not too expensive...

[GTRgeoff]

Don't know. It would just get dirty in mine anyway.

[blind_elk]

How much do the clear cam gear covers cost, might be a better option if not too expensive...

$185 @ Advan (as per latest HPI, p11)

[benm]

Is that for RB25DET or RB26DETT ?

[benl1981]

Is there anyway to check if mine is damaged. I get vibration at low revs and there was some tapping - i thought it was the lifters though.

There is a half moon in the CAS and a half moon in the engine side and mine just slides in - havent noticed anything unusual.

[benl1981]

How much do you need to space it to be safe?

[GTRgeoff]

OK to correct this at least a 2.5mm spacer/washer is required. The upside of not having the cover on is never resetting the timing advance no matter how often the CAS comes off

With the vibration, it turned out to be the harmonic balancer. It had started moving around and even tightening the bolt more did little. Ultimately the woodruff key had started rounding off and is a crank out repair so I used loctite bearing mount which will prevent movement. The vibration is completely gone.

Clear cam covers have only ever been made for RB26 to my knowledge.

[DriftinThruLife]

you can buy ones for the rb25 (as far as i remember). Try PSI parts in Melbourne. $130 off ebay. Not sure if they are cheaper if you buy them direct.

[PM-R33]

Dude thread is from 5 years ago..