Timing Nightmare This Weekend

[edizio]

I just needed the timing belt changed but even that turned out to be complex with this car. I knew I bought a well modified one but I expected most tuner garages would be able to set my mind at ease when changing a belt.

I bought a new belt, tensioner, idler and water pump to go on, I thought that was easy enough but it took about an hour for them to get the uprated balancer off. I can say I got slightly angry at them when they attempted to use a crow bar instead of the correct puller tool to do this. Eventually they got the right puller tool and as expected, it came off nicely. It's good to know everything was nice and clean down there, no visible leaks, no major wear that needs looking into so I'm happy from that perspective.

So, I did let them know that my timing was set at 20 degrees and that the intake and exhaust cams were offset at various mm settings on the HKS gears. Why on earth I found 'tip-ex' on the engine I will never know, surely there's a better way of determining the positions or some way of locking the cams/crank.

If you thought that was a nightmare, this is where the trouble really begins and my mechanical knowledge probably doesn't help at this point: -

The way they had marked it had the the crank offset by 1 tooth from its position (there is a little notch on the crank that shows this). They didn't align the gears and crank to where they are when you usually set a timing belt up because the said that the timing was different. I knew the engine was set up at 20 degrees so I just trusted that they knew what they were doing. At this point, all done, no interference and boom, CAS back on, in the center where it was marked with tip-ex. The engine didn't start, it just backfired and I'm suddenly panicking that they're breaking my car.

So, they check a few things as they didn't seem to believe me when I said that I've never flooded the engine by just turning it on and off before so it shouldn't just flood randomly if it's set up properly. It does have big injectors though so I see their point. So after taking the packs off and checking all is where it should be, the engine, once again, backfires and doesn't start. Upon determining this was a timing issue, they proceeded to strip it all down again and at this point said they had no choice but to put the crank at the notch, put the cam gears at their set positions and try again. All done, ready to start and the car just started backfiring again and at this point, they were saying that I needed to get the person who built the engine to tell me how it was set up so that they could get it right.

I pulled out my phone and gave an experienced engine builder a call who said that the problem sounded like they had snapped the little 'D' inside the CAS off and that no matter where the CAS was positioned, I'd never have the correct timing. We checked, and I had to put the builder on the phone with the mechanic as they were trying to tell me that I was misunderstanding but I knew what was going on now, the 'D' was missing from the cam and thus the CAS wasn't positioned correctly. The builder told them to inspect thoroughly that the piece wasn't to be found anywhere to confirm as this could have happened before at a previous timing belt change. This was probably the case because the metal that was left wasn't shining like a clean cut and was a bit dull and had bits of residue.

Upon placing the CAS properly into the cam, it started up and sounded fine and was the bubbly little idle tick over that I have it set at on the computer.

Concerns

So, now I'm really confused at whether the timing is actually set up correctly at all. I don't fully understand the cam/crank timing so I don't really know whether the belt should be set up to be a tooth out. They did mark the positioning of the old belt with this horrible tip-ex the first time. Both times the crank could be turned around twice without interference so I'm now worrying that maybe the timing was meant to be out by a tooth. I do have 264 toda cams and I don't really know whether having the crank off by 1 results in anything opening earlier or later etc. Since it was always the CAS that was the problem, I never got to hear/feel how the car was/would have driven when it was on the original marked settings. I keep saying to myself that the marks were probably just done wrong by the guys there and it is now set up properly but ugh!!!

I have always heard that if the crank is out by 1, the engine would barely run or at the very least, would be less than optimal. At the moment the car is driving fine but I've got this worry in the back of my mind that something could be wrong. I could swear it feels a bit laggier too but that could just be because I've been driven back to my home in my friend's R35 GTR which isn't as quick as mine once the turbo is going but has next to no lag.

Furthermore, if it does turn out that the crank was meant to be off by 1, can this be rectified by adjusting the cam gears/CAS/timing on the laptop?

Edited March 29, 2015 by edizio

[KiwiRS4T]

If I were you I would be going to a known good RB tuner and get him to check the cam timing (check is probably the wrong word - more like re-set). In other words if you are worried that all is not 100% and you might damage your engine get an expert RB tuner to do a tune. I would never get engine work done on a GTR at any random garage - best to get someone who is totally familiar with the RB engine.

Where are you located? Someone might be able to point you to a reputable shop.

[edizio]

I'm in the UK and I'm fortunately going to see a reputable tuner/mechanic for RBs in a few weeks so I'll ask him to check it out. It's annoying because I did take it to a reputable tuner garage.

The car has adjustable cam gears and they weren't changed. Just out of curiosity, how does someone set cam gear timing? sounds like quite a complex thing to do without knowing how the head was machined for flow rates or something? The head was machined out in Japan and polished ports etc.

[XGTRX]

With all due respect mate if anyone pulled out a crowbar to take the balancer off I would snap him one in the mouth. Just make sure these cowboys didn't f**k up your oil pump. Just check with a torch and make sure the cover isn't damaged. If it was me I would be towing it to the rb garage. Get him to do an assessment before he touches it, with pictures. Sorry mate but I wouldn't be risking a motor.

[Dobz]

KiwiRS4T second that.

XGTRX I'll second that also.

You don't know if they have set the crank timing right so you can't just go moving the cam pulleys around.

Cam timing is ideally set by lining up the factory marks on the oil pump and crank pulley and the cam pulley marks against the cam backing cover.

[KiwiRS4T]

I'm in the UK and I'm fortunately going to see a reputable tuner/mechanic for RBs in a few weeks so I'll ask him to check it out. It's annoying because I did take it to a reputable tuner garage.

The car has adjustable cam gears and they weren't changed. Just out of curiosity, how does someone set cam gear timing? sounds like quite a complex thing to do without knowing how the head was machined for flow rates or something? The head was machined out in Japan and polished ports etc.

Provided the cam belt was put on in the correct place in the first place adjustment is made on a dyno until the best or desired result is achieved - potentially a very time consuming exercise.

[edizio]

So I'm confused, I've spoken to a number of tuners who have said that as long as the degrees on the adjustable vernier cams haven't been changed and as long as the timing belt was set up with the cams and crank in their standard position, I'm fine.

[KiwiRS4T]

So I'm confused, I've spoken to a number of tuners who have said that as long as the degrees on the adjustable vernier cams haven't been changed and as long as the timing belt was set up with the cams and crank in their standard position, I'm fine.

That is correct. But for some reason you seemed to think that it was originally set up one tooth out (an unlikely scenario).

So if it was done right originally and the people who replaced the belt put it back correctly then you just need to check the CAS timing.

[edizio]

If it were out by 1, would it, in any scenario, drive normally?

Also, I unfortunately found out that the exhaust cam key was broken off but there's a couple of differing opinions going around on the forums

Opinion 1: -

You need to buy a new exhaust cam as the spline isn't strong enough

Opinion 2: -

The key was just there for positioning to help insert the CAS

If opinion 2 is correct then that's fairly good and at the moment, the car is driving normally.

[89CAL]

Its just there for positioning. Makes it much easier to locate. Spin the CAS with your hand, not much load right? You just need to pay attention to where the locator broke off then try and line the CAS up to it. Use a timing light to confirm

[r32-25t]

Some after market ecus also require the crank angle sensor to be put in a different position and that could be the reason for the key being broken off

[ido09s]

My half moon is gone, nothing to worry about until you remove the CAS as it can be a bitch to line back up

Does the engine have the cam cover fitted? Really easy to check cam to crank lines up if its not

put the crank on the zero timing mark. Check the dots on the cam gears line up with the lines on the timing cover backing plate. if they don't spin the crank pulley around 360 degrees and check them again. If they don't line up now you have issues. Regardless of cam timing the marks should like up. Post some pictures if your not sure

As for the workshop that did it, they are hacks and should not have a licence. No mechanic I know of would ever take to a harmonic balancer with a tyre lever unless its stuck and cannot be removed without force

[edizio]

I think maybe I'm just getting worked up over nothing. It's highly unlikely the car was a tooth out before and if it's been rectified and is driving the same as it was before, then that's probably the evidence.

I actually have put the CAS back in properly but I was just speaking to a tuner yesterday who said it was risky to run without the 'D' as the spline can slip and it will destroy the engine. He seemed like a genuine guy and is highly recommended for ECU tuning around here. He said I'd need to order myself a new camshaft to fix the issue; just to be safe.

[jiffo]

"I was just speaking to a tuner yesterday who said it was risky to run without the 'D' as the spline can slip and it will destroy the engine."

What a load of rubbish!!!

As has already been posted, some aftermarket ecu's need more range than the standard CAS adjusting slots can accommodate.

In those situations the locating tab must be removed so the CAS can be positioned to suit.

The spline does ALL the driving.

The locating tab is just that, a locating device for ease of positioning the CAS.

[edizio]

That's good to know jiffo, thanks.

I guess rumours go around now and again that cause people to believe these things.

[jiffo]

Hope you find a workshop that knows it's stuff, can give the engine a check over and then a dyno tune for your peace of mind..

And stay well away from that original crew.

[edizio]

Yes, thanks for the reassurance; it's going on the dyno next week. I'm excited for some results, I'll post them online so people can see. I've asked if they can check on the cam timing as well so she should be running perfectly again soon :-)

[ido09s]

I have been running a CAS with no D for years and was at one stage revving the car to 9000rpm and it hasn't skipped.

I used to work for one of the well known Sydney Skyline shops and we always removed them and have never heard of one skipping a tooth. Sounds to me like someone who claims to know Skylines and seems to want to remove a non issue to be safe.