Discussion in 'Z Re-builds' started by rob260, Dec 30, 2013.
wow , who built the heads before rob ?
The previous build was done by UAS
Dun dun dun
Also played around with the cam sync a little more.
The pic below shows the way the they key is supposed to fit. I say supposed to, because there is a dowel in the key (which I've punched out by this stage, but you can see where the hole for it is at roughly one o'clock) that slots into a hole in the cam gear. Now this is all fine and dandy, except that you need to slip the sensor housing over like the pic below in order for the key to trigger at 15* below TDC.
The downside to this is that there is SFA adjustability, and only two of the three housing mount-holes line up with the threads on the VG30 CAS mounting bracket.
To get the three holes to line up, the signal to trigger at 15* BTDC, and to get plenty of adjustment either side it really needs to fit up like this.
With the current key design the dowel in the key no longer lines up with the slot in the cam gear; I'd be quite happy to remove the dowel altogether except that the key is balanced (see that flat edge?) WITH the dowel... so the outcome of all of this is that Ross are going to make up a modified key for VG30 and send to me for test fitting.
By this stage some people will be tearing their hair out wondering a) why bother and b) why not just leave as is and correct the trigger offset in the ECU... There isn't a simple answer, except that I have the option of working with Ross to come up with something that is as good as factory (and consistent with what they offer for RB platforms for eg) so bugger me that's what I'm going to do. It's a more expensive route than modifying the factory CAS with an AEM disc but I don't much fancy pulling a CAS apart, and this design will have less possible points of failure (no bearings to wear out or drive pins to snap etc) once it's done.
Have you thought of just re-drilling the CAS braket ?
Did think of that and it would work just fine, also tried using an RB CAS bracket which fixed the sensor mount but didn't match the rest of the motor (different bolt pattern and fouled on the cam sprocket. At this stage though I'm happy to wait to get the parts 100% right.
cant you run a trigger setup off your ross racing crank dampner? cant remember who did it , but it was on this page looked like a nice setup
That is only half the trigger setup. Need a cam sync also.
And to think you brought them a dyno for that kind of workmanship!:rolleyes2:
Oil Consumption and Leaky Valve Diagnosis
Dropped back into the cylinder head shop this morning to have a chat about what they'd found.
The good news is that the JUN valve springs and Ti retainers are still in good working order (they still look new). The valve springs measured 150lb pressure @ 9.5mm lift with no bind so they're doing their job just fine. The exhaust valves also appear serviceable.
The bad news.
First the oil consumption. The heads have been fit with UAS supplied bronze valve guides which are a little too tall, and they have been making contact with the valve stem seals. As a result all 24 seals have literally been torn apart as in the pic below. This is a fairly easy fix (cut the guides to the correct height) and really should have been done when the heads were assembled.
With the amount of oil that has been coming past the seals the intake valves in particular are well and truly cooked.
The pic below shows the edge (the sealing surface) of one of the valves -it's hard to see in the picture but there's a concave lip in the surface tha tis preventing it from sealing properly.
The next pic shows one of the valves cleaned up -unfortunately to get the edges smooth requires a lot of material coming off and they end up too small to be serviceable.
So at this stage they're going to clean up all the valve guides and assuming they're OK (which they appear to be) the guides will get cut to the corrrect size and put back in the heads. The exhaust valves aren't showing any damage so looks like I'm shopping for stem seals and a set of intake valves then put it all back together and pressure test.
Again 440rwkw on a soft tune... it would have been a ****ing monster running on all cylinders
Ha thanks mate.
Re workmanship shit happen when you try new things out. What disappoints me is that these defects have been present since I got the car back and when I brought it back due to excessive oil consumption they gave me some bullshit about the turbos, which they charged me to "fix", rather than investigating the issue properly.
Yes the Link ECU will quite happily run ignition off the missing tooth (teeth) crank pulley, but it still needs a signal from the cam pulley to know if it is on an intake or an exhaust stroke. I could just as easily have modified a modified CAS but I like tinkering with this kind of stuff to try and find the "best" solution.
glad it's sorted man.
Just get cutting compound and hand drill with small choke that you can "grip the valve tip/stem with" once they in the head... slowly and carefully work them in...
If you don't have vacuum tester - test leaks with water - once they not leaking your done...
Way better results then machining....
Just wanted to clarify an error on my part with the valves. I ran the part numbers on the stems and they are in fact Ferrea 1mm oversize valves; they measured in at .5mm oversize because they have been worn down.
I wish it were that simple but they're missing just under .5mm -they'll never seal again
Wow! At least you've found the problem. Should be all sorted once you have it back together and run in. How many killerwasps this time?
glad you have found the cause of your issues, effectively you could have left your bottom end complete and just fixed the valve guides and valves
were there any bottom end issues ?
Bottom end looked ok -could have been as simple as fixing the heads but I've already started down the rabbit hole (again) lol
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