RB25 + inlet cam gear

Skyrine-Dave · March 18, 2005

How can this be?

I have the rb25 head on an Rb30 block... VCT has been disabled...So how can i put an adjustable cam gear on the inlet cam? The bolt pattern isnt the same?

Skyrine-Dave · March 19, 2005

any info at all?

Gradenko · March 19, 2005

the bolt pattern *is* the same. I have vct disabled on mine and an adj gear on the inlet cam. That's on a r33 rb25det head. What's yours?

sproosy · March 19, 2005

the bolt pattern *is* the same. I have vct disabled on mine and an adj gear on the inlet cam. That's on a r33 rb25det head. What's yours?

He has the rb25 head on an Rb30 block...

Gradenko · March 19, 2005

Yea-ha. But r33 rb25de, r33 rb25det, r34 rb25de or r34 rb25det? Obviously not a r32 rb25de as vct has been 'disabled'. The bolt patterns on all of those should be the same, but I'm trying to work out why the inlet on his is different.

sproosy · March 19, 2005

prob an R33 rb25det id say. but thats a poke in the dark

Skyrine-Dave · March 19, 2005

I am told its an R33 RB25det head.

The inlet cam has all that VCT crap on the front of the wheel. I havent seen this myself, but my mate who was putting the cam gear on said once he pulled the VCT stuff off there was just a single bolt straight down the guts of the cam gear holding it to the cam shaft... I thought this was weird as i thought they have 4 bolts plus a locating stud?

any more info?

blind_elk · March 19, 2005

Then you might have to try and fit a non-VVT inlet camshaft.

I'm not sure an adjustable cam wheel is so useful - on "standard" DE engines, the degree of adjustment is so small for the gains obtained that it's almost not worth the effort, IMHO. But it might be different on a RB30DE setup. And anyway, as I understand it, changing the cam timing simply shifts the power band, it doesn't necessarily improve it.

MonstaS4 · March 20, 2005

Isn't there adjustability on the standard VCT mechanism? I think it is accessed from behind, you probably need to remove it from the cam first. I've been meaning to try this but havn't had time.

GTRgeoff · March 20, 2005

Putting in reground GTR cams will allow removal of the VCT, without the issue of the solid lifter ramp angles on the cams and giving a little extra lift. So then you get higher lift cams, and can use a vernier cam gear to beter take advantage of the higher lift.

Skyrine-Dave · March 20, 2005

I think i'll have to go look at it myself and possibly take some photos as i havent heard of anyone mentioning this problem before.

Blind_elk: Its not naturally aspirated, its got a GT35r hanging off the side of it

Edit: I am wanting to put Tomei Poncams into it, so this may solve my problems.. But i am unsure how the Tomei cams will go in a 3L application... As they are made to work with the VCT it concerns me that they might not be suitable for the RB30DET setup

Gradenko · March 20, 2005

I am told its an R33 RB25det head.
The inlet cam has all that VCT crap on the front of the wheel. I havent seen this myself, but my mate who was putting the cam gear on said once he pulled the VCT stuff off there was just a single bolt straight down the guts of the cam gear holding it to the cam shaft... I thought this was weird as i thought they have 4 bolts plus a locating stud?

any more info?

It should have 4 bolts. This is mine:

I didn't fit mine myself, so it's entirely possible that the workshop made an adpater to make it fit, but I seriosuly doubt it. Get around to your engine and take a close look at it yourself.

GTRgeoff · March 20, 2005

WTF, that isn't an RB25det inlet cam front end. It isn't even an RB25 by the looks. RB30/31det as a guess from the tensioner location above the water pump and the amount of block above the pump. Were those cams custom?

The poncams would likely take the VCT cam gear so would leave you with the same deal, but I am no expert on them so get another opinion, but the improvement of the poncams alone would be worth the effort.

Gradenko · March 20, 2005

skylinegeoff, as I mentioned earlier, I am using a r33 rb25det head. You are quite correct about the block, not that it has much relevance for this topic.

I posted the pic so someone could tell us if mine has been modified to fit a cam gear on intake. I was never told otherwise when it was fitted. How does it compare to a standard cam inlet front end? They are factory r33 rb25det cams on intake and exhaust.

thizzle · March 20, 2005

i just did the same thing had to buy rb20 cam for that side

GTRgeoff · March 20, 2005

OK just to clarify, standard inlet cams will not have 4 bolts to locate the cam gear but a single one for the VCT gear. It also incorporates the seal surface on the cam gear. That one must have been modified. A bit of an expense for bugger all improvement when a GTR set that will take the vernier cam gears can be reground to suit RB25 with hydraulic lifters for $280 plus shipping at Ivan Tighe in Brisbane (one of the forum members works there). the added bonus with GTR cams is the added lift and duration giving a greater top end performance. Without the regrind the 25 has nothing under 5K rpm, as I fitted a set for a day to see for myself the effect.

That is, by the way a nice looking engine.

thizzle, are the 20 cams made with the same lift and duration? I never wasted any time to find out.

lukevl · March 21, 2005

Davey Boy how is your vehicle going?

The RB25VVT inlet cam is the only one with a different front out of all the RB cams. It is a single bolt front with a locating dowel.

I make adjustable centres to bolt on which use the standard outer to make it adjustable. Its quite easy and all you need is a different seal ($6) and a shorter bolt without a hole in it ($Stuff all) and loctite the bolt in so oil doesn't get past. You're looking at $120 incl GST at a guess. Call me on my mobile if you still have the number or at work.

GTRgeoff · March 21, 2005

And while your at it luke, give the cam regrinds a plug.

lukevl · March 21, 2005

hahaha yeah its a bit sad isn't it.

The only thing is that if I wrote the same post without saying prices the first Q is always "How much?" So I thought I'd write it.

Skyrine-Dave · March 21, 2005

si if i was to purchase a set of Tomei pon cams will i experience the same problem with the inlet cam shaft being a different bolt pattern?

Lukey boy: How can I bolt on my HKS adj cam gear to the inlet... the simplest and easiest method?

I am wanting to put a set of cams into this motor, but I want to know what is going to work on the motor... Your thoughts on the Tomei cams for RB25det ?

Car is being re-assembled and have hit this problem now... trying to sort it out.. All these slow downs shite me off

Oh yeah need something else PMing you

EDIT: looks like PM is down

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RB25 + inlet cam gear

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