Rb25/30 Build

[kayboom]

Hey mate,

Im in the middle of building a 25/30 at the moment and currently have the following.

S2 RB30 Block non turbo pistons with RB25DET Head (welded up VCT), 26 Cams

I have put a RB25 Cometic 1.3mm MHG with ARP RB25 Head Studs.

However, information i am seeing is rather mixed, some threads are saying *run an RB25 HG* and others are saying *the RB25 HG wont work, must run a 30 or 26*.

What is your experience?

also, do you by any chance know what style of balancer, idler pully and guide i should be running?

The block has been tapped.

Thanks

Cheers,

[N1GTR]

Wrong area. Moved.

[zebra]

26 cams in the 25 head won't work unless they are re-profiled to suit the hydraulic lifters. Also cams and lifters wear together running 20 year old cams from 1 engine with worn lifters from another can end in tears.

Use a 26 or 30 head gasket

Use a balancer to suit you car / ps pump / alternator

All twin cam RBs use the same cam belt idler pullies. So just buy the belt that suits and 2 new idler / tensioners

And don't forget a new stud and bolt for them

[JonnoHR31]

26 cams in the 25 head won't work unless they are re-profiled to suit the hydraulic lifters. Also cams and lifters wear together running 20 year old cams from 1 engine with worn lifters from another can end in tears.

Use a 26 or 30 head gasket

Use a balancer to suit you car / ps pump / alternator

All twin cam RBs use the same cam belt idler pullies. So just buy the belt that suits and 2 new idler / tensioners

And don't forget a new stud and bolt for them

this. rb25 head gasket will not work with a rb30 block. rb30 is the cheapest from nissan.

if you had just a 25 in your car before then use everything from the 25 (balancer, block fittings, oil cooler, oil and water pumps etc)

[Gerg_R31]

26 cams in the 25 head won't work unless they are re-profiled to suit the hydraulic lifters. Also cams and lifters wear together running 20 year old cams from 1 engine with worn lifters from another can end in tears.

I partly disagree with this part,

both 25 & 26 base circles on the cams have the same flat surface, if the lifters have wear marks (top of lifters has a indented grove from the cam) then id suggest to replace them

but yeah older motors have radiused base circles and lifters radiused to match the cam lobes so you can't mix them up, or the solid lifters unless you want to reset the clearances

[Adriano]

Plenty of people have tried rb26 cams in a hydraulic application(myself included), and they do not work.

[Adriano]

IMO, far better off running rb25 cams and enable the vct

[Gerg_R31]

What was their issue? Did you get it retuned?

Yeah i agree the vct cams will give better results

[tazzy]

like zebra was saying... re profiled cam, Ivan Tighe do a reground rb26 cam to fit the rb25 and the people i buy my parts from and tuner said i should have went with a tomei head gasket as it has the built in restrictor hope that helps