Adjustable cam gear install.

[JimX]

Right, I've done it! I had to kind of "squeeze" the wheel onto the mounting with the bolts, if that makes sense. I couldn't just push it but I got it really close and gently tightening the bolts on pushed it on.

I had a heart attack when I accidentally moved the inlet cam at one point! But it was only a millimetere or 2, less than the width of one tooth on the belt. So I very carefully put it back from whence it came. At least I think I did.

I tested cranking the engine before running it, to make sure valves weren't bouncing off the pistons. It all sounded good.

The car doesn't run too well in upper revs. I don't know if this because I screwed up the location of the cams, or if it just needs a tune. It does seem to run better at lower revs though so fingers crossed it's all ok. If not then the mechanics will have to re-do everything, so I may as well have not bothered. If it just needs to be tuned, then I've saved around $160.

[Jay95R33]

Good to see you got it on

If it's not running the best at 4 degrees (2 marks), knock it back to 3 degrees and see how it goes.

I set mine at 3 and I'm happy with the extra mid range pull.

J

[JimX]

Ok, I've definitely misaligned at least one of the cams, possibly both. Are there any marks I can line up on them to put it back to normal? I'm at most one tooth out on the inlet (but I'm tending towards it being ok), and definitely 1 or 2 on the exhaust.

I know that I'm 1-2 out on the exhaust because the car still ran like a dog when I put the adjustment back to 0. So I tried moving the exhaust cam one belt notch in the opposite direction to what I thought it was out in, but that didn't fix it. I wouldn't say it made it worse, but it made the problem slightly different. Which is why I think the inlet might also be out.

If there are no marks I can use to bring it back to normal, I think I'll take it to the mechanics sometime during the week

[Jay95R33]

Damn, not good

I'd be very careful when playing around with the belt.. The last thing you want is to let a valve touch the piston

Did you do everything at TDC??

Re-align the dots on the cam wheels (one on each wheel) with the marks on the backing plate for the cam cover and make sure the crank is TDC with piston number one.

It doesn't really matter where the belt sits on the cam gears, just as long as everthing (crank and both cam wheels) lines up when the belt is on.

You really need to get your hands on a 27mm socket so you can rotate the crank to TDC and then see where the cam gears are compared to it....

J

[JimX]

I can get it to TDC by cranking the engine a split second at a time Where is the mark for TDC on the crank anyway? I went off the top of the exhaust cam wheel dot when lining it up earlier, but obviously I can't go by that now because it's out by a few degrees. And it was probably not TDC either.

I know the belt location isn't important, but if you move the cam more than one belt tooth's width, the cam wheel will go on in the exact same spot but the cam will be a few degrees out.

So basically, where should all the dots be when the crank at TDC? If I can find TDC on the crank and know where the dots on the cam wheels should be I should be able to work it out.

I just checked then, when the inlet cam dot is at the top the exhaust is way off to one side. How are they meant to line up?

[Emre]

Jim,

From memory, the markings which the dots on the cam gears are supposed to be aligned with are at 10 o'clock position for the inlet cam and 2 o'clock position for the exhaust cam.

Some of the cam gears are designed, so the dot on the gear lines up with the '0', like yours seem to be. With this type, they will look tilted in the opposite direction once on the car.

Other cam gears are deisgned so when the dots line up, the '0' will be upright in the 12 o'clock position. If you zoom in the pictures i am attaching you will see what i mean.

So, if you had directions from someone with this type of cam gear installed, you can get confused, which is what i think has happenned. In reality, it does not make a difference which way the '0' is facing, but it's critical that you line everything up properly.

[JimX]

I can get the dots roughly into that position, but it's still going to be 1-2 teeth on the belt out I think, because I can't get it lined up that precisely.

Also, I still haven't found the TDC mark on the crank. I'll have another look with the cams in roughly those positions I guess, maybe that will make it easier.

[JimX]

I just spoke to Marcus from Hills Motorsports, and he said that there are 2 marks on the plate behind the cam wheels where the dots are meant to line up when the crank is at TDC. I'll take another look when I get home tonight. If that's the case then I've nfi why I didn't notice them before. Maybe they're just covered in dirt

[Emre]

If you weren't aware of the markings @ 10 and 2 o'clock positions on the backing plate, what did you line the dots up with ?

[JimX]

I cranked the engine over until the dot on the exhaust cam was at 12 o'clock and lined it up from there. In the process I accidentally nudged the inlet cam slightly, which was the beginning of my problems. After I put it back to where I thought it was, the exhaust cam didn't line up properly, so again I had to take a stab at it. It was all only off by 0-2 teeth on the belt at maximum, which is less than the range of the adjustment on the wheel so I was confident I wasn't going to bend any valves.

[Emre]

When the dot on the exhaust cam gear was @ 12 o'clock position, the dot on the inlet cam gear would have been @ 8 o'clock position... Right...?

Did you install the cams gears when they were in this position...? The other difference i see with your cam gears is that, they seem to have 2 locating pin holes. So you may have installed the inlet cam gear with the dot facing 2 o'clock position....?

[JimX]

I actually have no idea of where the inlet cam dot was when I lined up the exhaust. Thus my main failing I guess, when I realised I bumped the inlet cam and had to guess where it came from. I'm pretty sure that the inlet is back where it came from but tonight I'll make sure.

The exhaust cam went on the correct way, because I took note of where the dot was on the original wheel. I thought it *might* have been 180 degrees out, but I'm now absolutely sure it wasn't. I think I would have bent some valves by now if it was.

This has been a big learning experience for me. One other thing I've learned is that it's easier to adjust the wheel once it's on, because it's harder to line things up when the wheel is off by 1-2 degrees. It's harder to see the numbers when the wheel is on but using a mirror it's easy to line it up as precisely as when it's off.

[Jay95R33]

Got some pics for ya.

OK, the first thing you must do is get the crank at TDC. You'll have to manually rotate the crank until you see the timing marks on the crank and then line them up with the timing mark on the cam cover (see pic).

The timing marks should be painted white on the crank, if you can't see them then look for 4 indents on the crank cause that will be them. You want to line up the far LEFT mark on the crank with the marker on the cam cover (which is circled in the pic on the righthand side). You can also see the timing marks on the crank in the pic (circled on the left side) but I couldn't get them to line up by just cranking the engine with the starter motor..

This pic looks a bit strange cause I have taken off the thermo fan.

Only proceed when the crank is smack on TDC

The next pic is just a pic of the front of the motor. The red circles in this pic shows approximatly where the marks (also should be white 'dashes') on the cam cover backing plate. You'll only see these marks with the front cover off so you can see the cam gears.

The marks will be at about 10 o'clock on the inlet side, and 2 o'clock on the exhaust side.

With the crank at TDC, and adjustable exhaust cam gear set at zero, you need to get the 'dot' on the inlet cam to line up with the 'dash' on the cam cover backing plate that's at 10 o'clock. Then get the 'dot' on the exhaust cam wheel to line up with the 'dash' at 2 o'clock on the cam cover backing plate.

That will set everything back to stock. Once all together, rotate the crank a full 360 degrees manually a few times (check for clearences) and then recheck that the dots and dashes still line up.

I hope that helps.

J

[JimX]

Thanks for the pics, they help heaps. Also thanks for mentioning that it's the left mark I'm lining up and not the middle one. What are the other 2 marks for then?

I think it'll be ok from here. Except I have to work until 6 today, argh! I just wanna get home and get it all fixed up and go for a hoon

[Jay95R33]

Cool, that's no problems.

Yeah, the four marks are for timing. The far left is TDC, then I'm pretty sure that the next one it 5 degrees before TDC, then the next is 10 degrees BTDC etc...

Lucky it's day light savings, won't get dark until after 8pm....

J

[JimX]

Yay! Finally got everything back together in the right place. The exhaust cam was only one tooth off, and the inlet cam as I suspected was all ok. I'm getting to be an expert at this now, it didn't take long at all to get everything off and adjust it all. It took about 5 minutes of tapping the starter until I got TDC up though.

So, after all this, I'm .... right back where I started. I tried 3 and 4 degrees, and neither of them worked very well. So I put it back to zero! I'm sure this is only because the PowerFC needs to be tuned for it, and also my injectors and AFM upgraded. They'll be done along with the tune, so it should all be ok from there.

Before I take it in, I'm going to ask the shop if I should set it to 3 or 4 degrees just to save them some effort (and me some money).

[Jay95R33]

Woot Woot

Good stuff..

Strange that it didn't run good at 3 and 4...

Are you still using the base map on the PFC or has it been tuned (and it's getting retuned later)?

J

[Sydneykid]

Hi JimX are you sure you were RETARDING the exhaust cam timing by 4 degrees? Not ADVANCING by 4 degrees?

Every RB25DET I have done responds positively and noticeably to a few degrees of retard.

I assume you were resetting the igntion timing to its previous position, confirmed with a timing light. Otherwise you will have 4 degrees retarded ignition which will badly affect performance and negate any advantage from the cam timing.

Hope that helps

[JimX]

Jay, using base PowerFC map for now.

Gary, running 4 degrees (2 notches) retard as far as I can tell. Once everything is in, I tapped the cam anti-clockwise to the desired notch. This is retard isn't it?

I didn't confirm the timing with a timing light, because this was Yet Another Half-Arsed Job By JimX. (YAHAJBJ for short). I just used the PowerFC readout of the ignition advance at idle.

I do have a timing light, but I haven't tried it yet. I'm not sure if it's sensitive enough to work off that white wire loop but I'll give it a go.

So what do you think I should do? Set the 4 degrees back on and set the timing to say 15 degrees? Is the base PowerFC map going to cope?

[JimX]

Oh yeah, I'd like to add in my own notes as well.

Firstly, if you don't have a 27mm socket, you *can* crank the engine over with the starter motor to get it to TDC. But you have to be more lucky than skillful, so make sure you have a fully charged battery. I also imagine it's not very good for your starter motor or battery, but hopefully it's not something you have to do very often. Just "tapping" the key will spin the crank around 30-40 degrees, so it's pretty hard to do minor adjustments.

Secondly, be careful when putting the CAS back on. I used the bolts to "pull" the CAS onto the bracket, and I ended up snapping a bolt and breaking the mounting bracket! A replacement was $25 from Just Jap. I later discovered that the best way to do it is to tighten up everything as far as it'll go without forcing it, then spinning the engine. This will pull the CAS into the bracket and you can then tighten the bolts properly without forcing it. A bit of grease between the CAS and bracket also helps.

Thirdly, I would either adjust the cam after the wheel is put on at zero degrees, or rotate the cam rather than the crank, if you don't have a 27mm socket to rotate it (ie, this would make rotating the crank impossible). It's fairly easy to tap the cam to the desired angle once it's on so my preference is to adjust it once everything's on.

Lastly, BE VERY CAREFUL around the exposed crank pulley cover. At one point I thought I'd dropped an allen key down into there, and I nearly had a heart attack. I tried pulling the cover off but could only get to one bolt, and I didn't have any magnetic probe things to fish around. I then thought about the noise it made when it fell, it was more plasticky than metallic, and after another brief search I found it on the radiator shroud. But after that I was 100 times more careful of dropping things down there so it was a good lesson learned.

Anyone else that's contemplating it but isn't sure, I say go for it. Just learn from the hard lessons I learned so you should be able to get it first go without stuffing up. I think I could do it in under an hour next time, so I'm not sure why most workshops quote around 2 hours. Jay can do 2 in 3 hours with pizza in the middle, so an hour seems about right for us Mr Averages

Even though because of all the setbacks I had and mistakes I did it took over 3 hours over a couple of days, I saved $160 (workshop price quote) which is more than I get paid at work anyway. I also learned a hell of a lot of stuff so I could do it again much more easily, and I just feel a lot smarter in general for it.