Locking Vct

[skylite]

Hi,

im disableing my vct on my rb30det. has anyone locked the vct gear as well as sealing the oil gallery. and is it nessesary to lock the gear.

Cheers

[Pauly33GTS-t]

Why would you want to disable VCT? doesnt it improve low down torque?

[ovabooster]

i got tomei poncams and a set of adj cam gears to go...If i were to disable vct to run both inlet and ex gears, is there anyway to remove that nob hanging of the inlet? I think its the solenoid???? If so i could put on a rb26 clear cam cover??

[drgnball34]

any1?

[Adriano]

What camgears are your cams designed to bolt to, the VCT cam has a different camgear mounting than the exhaust gear. Either a 4 bolt mounting or a single centre bolt. If its a 4 bolt style, then you wont be able to fit the VCT unit on the front of the cam, so adjustables would be the logical thing to fit, if its a single centre bolt style, then adjustable camgears wont fit, and youll have to use the standard VCT gear, to disable it you simply dont hook up the wiring to the solenoid. If its an r33 head, then you still need to hook up an external oil feed to the vct soleniod, as it also feeds a cam journal, if you dont, the cam will sieze and possibly break.

[ovabooster]

has any1 disabled their vct in a r34? did you need a oil feed to the solenoid like the r33?

[joeyjoejoejuniorshabadoo]

Aren't tomei poncams designed to run WITH vct anyway?

[ovabooster]

yeh thats right. I had a look at my inlet cam which has a single bolt pattern so trying to figure out how to still bolt on the inlet cam gear with 4 bolts pattern. U maybe asking why i would want to disable it in the first place...I have spoken to another person who using a NEO head + GTR cams which enables to run both inlet and exh adj cams and he said by dialiing them in, there were huge differences to the power band....and 500rwhp so to speak. My setup will be hardly stock and aiming for similar power. I heard of someone saying that it is possible to make up a plate to bolt it on??? Can this be done?

[R34GTFOUR]

yeh thats right. I had a look at my inlet cam which has a single bolt pattern so trying to figure out how to still bolt on the inlet cam gear with 4 bolts pattern. U maybe asking why i would want to disable it in the first place...I have spoken to another person who using a NEO head + GTR cams which enables to run both inlet and exh adj cams and he said by dialiing them in, there were huge differences to the power band....and 500rwhp so to speak. My setup will be hardly stock and aiming for similar power. I heard of someone saying that it is possible to make up a plate to bolt it on??? Can this be done?

yeah im interested in this aswell.

From what i've gathered you cant run your adjustable cam gear with the tomie cam thats been designed with vct, cause as you said your cam gear has 4 bolts and the vct inlet cam has 1 and obviosly wont bolt up. I think it was lukevl, that was in another thread that you replied in about your cams, that mentioned that he made adaptors so the stock vct inlet cam could have an adjustable gear put on so i would assume that you could get that same adaptor and put it on your tomie cam to fit the cam gear.

So if you didnt buy your cams yet, i think the better option would to by the normal tomie neo exhaust cam like you have and for the inlet side by a tomie (or whatever) inlet cam that is suited to a non vct rb25 so you can install the cam gear.

or

Get a set of gtr cams and bolt them in and since the gtr doesnt run vct you can put both cam gears on without any dramas, also since the neo head runs solid lifters i doubt you would need the gtr cams reground to suit a hydralic lifter setup in the r33 rb25 head

Edited November 21, 2007 by R34GTFOUR

[R34GTFOUR]

dont want to hijack this thread but...

i have found that quite a few people doing the rb30det build are disabling vct and i was just wondering why? you still have to provide an extrenal oil feed to it regardless if you are using it as that oil feed also runs into the cam journels for lubrication, so if you have the oil supply there, why not use it for vct aswell, its not like its any extra work?

SK said that he had found that the tomie cams were well tuned out of the box, and he didnt notice any difference with adjustable cam gears, so why not run vct on the inlet side and get that better down low torque and have an adjustable cam gear on the exhaust side and use that to fine tune it?

just wondering cause im looking into this build for myself and need to get these sort of things understood before i start buying lots of expensive parts

Edited November 21, 2007 by R34GTFOUR

[ovabooster]

i wonder when sk experienced little gains with adj gears it was with moderate power? Does it neccasarly mean that they wont have an affect on high powered applications? I already got the cams damit!!! I might sell them and get the tomei GTR cams instead although i have been told that NEO heads can only have lift no bigger then 9.5ish...

[R34GTFOUR]

what about the cas side of things? does the gtr run the same cas as the neo motor cause the last thing you want to do is get a gtr exhaust cam and find out that the r34 cas wont bolt up. You might have to get a tomie gtr inlet cam so that you can disable vct and still run your adjustabe cam gear but then buy a tomie neo exhaust cam so you can still use the cas (if they are different than the gtr)

your gonna be my guinea pig cause i'll be doing something similar and i need to sort this out aswell lol

[StockyMcStock]

Here are the instructions on how to disable the VCT on your RB30DET with no external oil feed required. Just two little grub screws and a welsh plug

I wish i had a better photograph (with the rear timing cover off) but i don't, so this will have to do:

where i have marked (approximately) on the head there is what appears to be a copper welsh plug. It looks, from the outside, like a normal welsh plug, but it is not. it blocks the front cam bearing from recieving any oil via the lifter oil feed rail (big long casting hole which runs next to the lifters, you'll see it with the cam cover off). it supplies high pressure oil to the lifters and cam lobes, and is fed via the block oil restrictors.

what you need to do is drill that welsh plug out. you'll see what i mean about it not being normal once you're through the first layer of it. don't do this with the engine assembled, swarf goes everywhere!

when you have removed that weird looking plug, the front cam bearing is now recieving high pressure oil all the time, same as the other lifters.

now, there are two holes in the cam bearing face, one is connected to the lifter's oil feed (high pressure) and one is not. you block the one that is not with a grub screw (tap it in, screw it in, stake it) and drill a hole in another grub screw as an oil restrictor (same size as the other cam bearings' holes). this other grub screw (restrictor) then goes into the hole that is now connected to the lifter's oil feed. plug the welsh plug hole up with..... a welsh plug (18mm i think from memory?) and you're done.

so what you have in effect now is, a full oil supply to that front cam bearing all the time. problem is, this will activate your VCT all the time! not good! 20 degrees of cam advance isn't as good as it sounds. the cam has a trench milled in it with a couple of holes which allows the oil to pass through to the VCT mechanism.

so you need to take the big eye bolt out of the funky cam end and weld the bolt closed. this normally allows passage of the high pressure oil to the VCT mechanism in the end of the cam gear. with this welded closed, no oil can get through to the mechanism.

if you have a head apart, you can easily see what i mean. it's hard to understand without pics but anyone who's taken one of these apart will know what i'm talking about.

2500km on mine and going strong - it must be working!

cheers

[R34GTFOUR]

top info mate, thanks something to think about

either way i definately running aftermarket cams so im still undersided whether just to delete vct and run an adjustable cam gears with either an external oil feed for the front bearing or do what you do

or

just run an external oil feed and keep vct (tomie poncams are designed for it anyway) and have an adjustable cam gear on the exhaust side only

hmmm, if got some thinking to do...

Edited November 22, 2007 by R34GTFOUR

[ovabooster]

great info mate. Now u got me thinking about the cas on the exh cam...spool imports on this forum is using hks gtr cams + both adj cam gears on his NEO 25/30. So it must bolt on the same...Anyone confirm this??

[FineLine]

Deleted vct on my 25 so i could run solids and adjustable cam gears. Currently running gtr pons (260% and 9.1 lift)

Done about 5 kay so far and no issues. Sounds porn and goes hard. Will probably upgrade to higher spec cams in the new year.

Part throttle cruising takes some getting used to. its either on throttle or off it but once you learn it its fine.

Just remember you dont have any adjustability when setting your valve lash. be sure that whoever assembles the head knows what they are doing.

[ovabooster]

excact same cams as im going to use. Did you have ur head ported ect? So CAS bolted up fine then

[ovabooster]

i went and had alook at my CAS since the head is off to get a better understanding of how they work and fit. From what i can tell the only thing that will stop the CAS from bolting up is a different bolt pattern on the cam cover. Other then that its pretty much a long bolt thats slotted into the end of the cam. Im sure all RB engines are the same.

[R34GTFOUR]

i went and had alook at my CAS since the head is off to get a better understanding of how they work and fit. From what i can tell the only thing that will stop the CAS from bolting up is a different bolt pattern on the cam cover. Other then that its pretty much a long bolt thats slotted into the end of the cam. Im sure all RB engines are the same.

nah its the actual key that varies. If you look at the cas where it slides into the cam the keyway might be different. I definately know r33 and r34 cas's are different and wont bolt on opposite motors. Worse case senario, if the gtr cams do run a different cas to what you have, just get that gtr cas and use that instead.

The 3 bolt pattern that bolts the cas to the front cover is the same across the skylines, its just the keyway that varies..

[drgnball34]

if anyone has access to R34 GTR cams and could take some pictures would be good.