im bout to do this conversion but not sure if ill b keepin the vvt or not can u list all the parts that u bought n rough prices so i can get an idea of wot im up for? also how much was the machining on the head n did u just go to a head joint n they knew wot to do or did u hav to tell them wot needed to b done? cheers Troy

Keep the variable cam timing - VCT. Its well worth it.

TroyVK, i took both the RB25 and 30 head gaskets to an engine rebuilder so they could see the differences in the 2 blocks. Pretty easy to tell where metal needs to be added to the head to give enough sealing for the water jacket. It's also easy to see where the VCT oil gallery runs, so i told em to drill and tap a hole into it and plug off the entrance which would have come from the block. The cams had to be removed to weld the head and surface it, so all up this work came to $200 Bundy tube and fittings - $20-$30 Nissan head gasket - $80 2 seals for cams - $10 u need 2 cam tensioners (not idlers) - $60 each cam belt - ?????? havn't decided what to use yet RB20/25 exhaust manifold - $100 External gate - $$$ Garrett GT30 - $$$$$ Aftermarket ECU - $$$$$$$ Where do you stop! Some original photos have not been recovered yet.

Quote: Originally Posted by MonstaS4 Twinvl, thanks! Yours was one of few sites which had excellent info on the head VCT conversion, so thank YOU! I spoke to Gates Australia about this belt but they say the temperature rating of this belt is lower than a standard timing belt. I have found a Dayco belt which is 150 teeth, 1200mm long, 8mm pitch but only 23mm wide. I will probably go with this, as i can't see 2mm making much difference in strength. Waddaya think? Hybrid vl, don't think it's worth changing unless yours is ****ed. There's plenty of cams around to trick up the non vct head. You may lose some fuel economy when cruising though. 2mm off 25mm is 8.5%... I'd say it would be ok but i wouldn't like to say fit big cams and hard valve springs... Or see if you can get this belt cut to 25mm??? I never thought of, or was told about a temperature rating... I'll give it a go anyway cos i've got the belt. Cheers MonstaS4!

Although the guy at Gates said the powergrip belt had a lower temp rating, he did say it will be fine to use in this application....just inspect it more often. So at a guess every 25-30,000kms. I've gone full circle, and i think the above might be the safest option. Using a belt that is possibly 8% weaker than standard on an engine that is 50%+ more powerfull than standard sounds pretty risky. Quote: also if anybody needs any pricing on gates belts and stuff i can help i work for a gates distributor so i can get real good prices Calais30T, the Gates powergrip belt is a GT2 1200 8MGT 30, but it will have to be cut down to 25mm wide. Can you get a price on this, and how do we (the general public) access this price?

sum1 keeps deletin my posts i want to know exactly wot parts i need to go buy to run the external feed for the VCT can ne1 help me? and yeah a price on the belt would b good

Belt is around $80. Don't forget Nissan exhaust manifold gaskets which are about $90. I am trying to get some made but

TroyVK, not exactly sure on the size of the brass fittings but i think the oil pressure fitting is 1/8" BSP. Just take the oil pressure sender to the hydraulics shop and get them to find fittings to suit. You'll need a 1/8" nipple (insert schoolkid giggle here...) to screw into the block, an 1/8" female T-piece, which will screw onto the nipple. The oil pressure sender will screw into the end of the T, although you may need a 45 degree fitting so it will clear the starter. Then you need 2 1/8" male fittings with bundy tube fittings on the end. Again, it depends where the hole is drilled in the head as to what fittings you will need here. I used a 45 deg, Twinvl has used a 90 deg. Once you have the fittings in place, use a coat hanger and shape it the same as you want the bundy tube made. The hydraulic shop will bend the bundy using the coat hanger as a template, and they will flare the ends for u. Don't forget to restrict the oil flow to the same size as the RB25's oil gallery.

Quote: Originally Posted by MonstaS4 Calais30T, the Gates powergrip belt is a GT2 1200 8MGT 30, but it will have to be cut down to 25mm wide. Can you get a price on this, and how do we (the general public) access this price? Talk about going round in ****ing circles.... I've just gone to order one of these belts, but the profile is not the same as the RB30 or RB25 belts. The gates belt is an industrial timing belt and has a round profile, whereas the RB belts have trapezoidal profile like this: __________________ \___/ \___/ \___/ \__ The gates belt dosn't appear to mesh very well with the RB pulleys due to the rounded teeth. Looks like drilling and tapping a new hole to mount the tensioner above the water pump and allow the dayco 94407 belt to be used, is the safest bet. More ****ing around to get the hole in the right spot, but at least the belt is identical to standard, just longer.

Just out of interest, how deep do you drill the hole in the top of the block for the reloacted tensioner when useing a Dayco 94407 Timeing belt? I've got everything else ready to go, etc How deep? Some original photos have not been recovered yet.

Be very carefull!! Drill it with the head off so you know how much metal is behind it. I though i would be able to use a gates belt and wouldn't need to drill a hole so i put the head on. Then realised i had to drill a hole, didn't know how much metal was behind it and drilled straight through into the water jacket! Pretty sure you won't be able to use the full length of the stud. I cut about 2-3mm off mine to get the shank to bottom out.

THATS what I was afraid of doing I've got everything for the conversion sussed, except that...... ....Also I assume you tried to use a Dayco 94407 belt and used the two tensioners down the bottom (aka useing the Gates Powergrip belt), before comeing to the conclusion that you have to use a relocated tensioner? If not when I get my short motor together, I have to see IF you can use a easy to get Dayco 94407 belt (I just went into motor trades, gave them the part number, and they had one on the shelf out the back!! Its also used on some Audi...) with the tensioners down the bottom.....anybody else tried this? Thats for your help! That took a heap of stress out of the conversion... Too bad the RB Twin cam heads dont have the belt tensioner attached to the head, aka CA16 and CA18...that would have made life MUCH easier....*sigh* Some original photos have not been recovered yet.

Tried that. It's too long. The belt will touch together between the tensioners. To save some stress, maybe get a machine shop to drill it for you. I put a grub screw and some loctite pipe sealant in the hole i ****ed up, then re-drilled just to the left of it. Now both tensioners are on full adjustment and the cam gears are retarded by a few degrees Some original photos have not been recovered yet.

Ah......well I do have a spare RB30E block floating around, I'll do a trial run on that and see how it goes I assume there are no other block diffrences between the serries 1 and serries 2 blocks besides the Turbo oil and water holes -- RB30E not RB30ET blocks? The point is I don't want to take too much off the tensioner stud, and have the stud snap some time down the road on me......No bent valves etc please!!!! .....still, I've been told the RB30E/ET are free running engines, I'd assume the RB25 is not? I've heard a Skyline owner who lost a timeing belt tensioner on his RB20DET, and ended up with bent valves.....I wonder if the RB25 and 26 are the same? I know Holden used to go by the idea, that ALL their engines where free running....?!? I wonder if a Hybrid RB30DE is a free running engine? I haven't got the head off my RB25DE vvt I purchased, or the RB30 short motor together, so I can't check yet......any comments? Oh why can't these be like Alfa Romeo motors Some original photos have not been recovered yet.

I carefully wound over both cams before i put on the belt with no 1 piston on TDC. It appears it is free running. No idea how close it is though. A bit of heat in there and they may touch?

Probably not, as the RB30E pistons are smaller in height than the RB25DE (non turbz) pistons, hence lower compression.....

I checked the clearences with playdough! It's close, real close but only on the edge of the RB30E piston valve reliefs so it would be easy to cut the piston a little more to give good clearence. Also i checked it without oil pressure so the lifter could have been compressed, didn't appear to be but how do u tell?? I'm pretty sure if the belt let go at full revs, the strech in the rods/bearing play ect. would allow the pistons to hit the valves, how hard is the question. I'd reather not find out. RB25DE's are defenently not free running... MonstaS4 - i see what u mean about the gates belt having rounded teeth but this hasn't caused a problem... Yet... I should have my RB30DE running finally this week, will let u know how it goes!! Also the inlet cam timing might have been out 1 deg or so with the gates belt, exhaust cam was spot on.

Just hope it doesn't let go/jump a tooth at 6000 odd RPM It will be just like a Alfa Romeo 164 motor (3 litre V6) when the oil driven tensioners let go (design fault) and the belt jumps 2 teeth......ouch...... Some original photos have not been recovered yet.

I got it running! Just using a RB30E ecu and injectors, and i made a decoder to divide up the ignition pulse for the multi coils. Works perfectly! Haven't driven it yet cos i'm lacking a few parts because i crashed her a few weeks ago... The belt viabrated on the slack side at particular revs but reved all the way without any probs. I took it off and checked if the valves could touch the piston. set the crank at TDC and i could turn both cams around and around! I'm abit less worried about it now. I put the belt back on and tentioned it up alittle more. Seemed better but not much. Also, turning the VVT solinoid on and off doesn't seem to make any difference at idle??

I guess at idle, the air speed is soo slow that the difference is not noticable. Plus I think it only does its job when the engine is under load. The other thing is doing this head conversion and increasing compression to 11:1 would probably make it difficult to turn the cams a full 360 at TDC?