Neo Noisy Cams

[Huzqld]

Anyone got some tips as to what is going on here.

Cam tech 270- 9.5mm cams no vct

Shimmed to

.010" intake

.012" exhaust

+\- .001"

Pretty confident of the clearances, have checked twice. Cams don't appear to be hitting anything. Can't see any marks on Pistons (checked with bore scope). Listened with stethoscope and it sounds valve train related...

Running performance springs.

Stock cams were quiet. Same springs just changed clearance

Edited May 21, 2015 by Huzqld

[Huzqld]

Sounds like a diesel

[Ben C34]

Didn't watch.

Aask camtech

[Kinks]

I'm no cam expert (and no idea how to diag by the sound of it), but how did you decide on the clearances and are those hot or cold readings?

http://www.sau.com.au/forums/topic/397382-rb25det-neo-r34-gt-t-valve-clearances-solid-lifters/

Workshop manual in the above thread says 0.31mm intake and 0.51mm exhaust when cold.

0.31mm = 0.012" which is close to your figure.

0.51mm = 0.020" so your exhaust side has about half the clearance it should have

[Huzqld]

Have asked camtech. They Aren't really sure what's going on. Obviously more investigating to do.

But always Good to see if anyone else has had issues similar

Came up with those clearances as that's what it says on the cam card they are cold readings.

You are right though the factory cams do run with bigger clearance and that is what I had the stock cams set to and the engine was quiet as.

Edited May 23, 2015 by Huzqld

[methz]

I got the camtech 272s and retained the vct, once mine were installed, my vct flogged out and i got alot of noises, replaced vct gear and it went back to normal quiet as. not sure if that helps.

[Ben C34]

Does the vct still have oil going to it?

[methz]

Mine? yes the intake cam was drilled with oil gallery if thats what ur asking. it was like a week after cam install the vct rattled and made noises. was still fine to drive/power on. just shit house noise.

[Huzqld]

Not running vct in mine anymore.

Triple checked the clearances and it is as per cam card.

Retarded the intake and advanced the exhaust just to see if the noise changed (doing this should effectively give more piston to valve clearance?)

No change in noise.

Will keep investigating.

[Kinks]

The VCT assembly will still need some form of lubrication even if you're not using it. I remember reading some issues a while back about someone swapping heads and didn't keep the VCT oil feed and then had cam bearing issues. But if you are using the stock head and have just unplugged the actuator electronics then it will be fine. Didn't realise the cam had to be modified with a gallery too, sounds interesting.

What viscosity of oil are you using?

[Simon-S14]

why would you not use the VCT?

[Dale FZ1]

Were any checks made to see how the valve springs coped with the valve lift you're using?

And do you know what sort of weight is on the nose of the cam?

Basic setup questions really, made me wonder what's been done.

[Huzqld]

Whoever originally done the vct setup on this head has done it a completely different way to what I've seen them done. They drilled down through the cam gallery and into the vct feed and grub screwed the top hole.

I found the thread somewhere but can't find it now.

But it hasn't worked, the vct half kicks in and then the car just idles normally again. (When testing at idle) made no difference to dyno graph either.

Plus it's an auto with a 3k stall and will probably go bigger down the track.

Didn't check the valve springs honestly (we should have) but they should cope with that lift.. They aren't stock springs and plenty of people have used them on bigger cams then this. They are the 'performance valve springs' springs and ti retainers.

Not sure what you mean by weight on nose of cam, but am only running adjustable gears.

I've packed the cams up and sent them back to camtech to check out.

Put the stock cams back in just to make sure and it's back to being very quiet.

[STATUS]

A customer had a similar issue with those cams in a r33, fitted procams and the noises disappeared.... never heard the outcome unfortunately.

[Huzqld]

Ended up with some 9.2mm 270's (instead of the 9.5mm). With a nissan spec ramp on the cams. Bit bigger clearances (.017" in- .019" Ex. No more noise, so not really sure what was going in..

[Dale FZ1]

I'd say probably some fully compressed valve spring length issues.

As long as it's now a happy combination you should be set. VCT setup, or fixed cams now?

Report back with some results please.

[Huzqld]

No VCT now, just adjustable cam gears. Hoping for a tune in the next couple weeks. Also went to a full crank trigger setup so I cant have any CAS issues

[Ben C34]

Why no vct?

[Huzqld]

Whoever originally done the vct setup on this head has done it a completely different way to what I've seen them done. They drilled down through the cam gallery and into the vct feed and grub screwed the top hole.

I found the thread somewhere but can't find it now.

But it hasn't worked, the vct half kicks in and then the car just idles normally again. (When testing at idle) made no difference to dyno graph either.

Plus it's an auto with a 3k stall and will probably go bigger stall down the track.

^

The solenoid seemed fine, maybe it was the gear, not really sure. Anyway, no more.

[methz]

Good news you found the problem though

I wasnt aware camtech done a 270 degree cam? ive got there 272 with 9mm lift.

Edited June 9, 2015 by methz