Rb30det/tt Gtr Conversion Thread

[spooledup]

ive heard that if you have a RB25DET head and a VL commodore block (RB30) all that needs to be done is the bolt holes on the head need to be drilled out and retapped and then its a straight bolt on, i know its not much help to you guys wanting to do rb26/rb30 conversions but yehh

[bubba]

ive heard that if you have a RB25DET head and a VL commodore block (RB30) all that needs to be done is the bolt holes on the head need to be drilled out and retapped and then its a straight bolt on, i know its not much help to you guys wanting to do rb26/rb30 conversions but yehh

wut?

25DET heads need a gallery welded to suit the 30 block and AFAIK only 26 heads need the block drilled/tapped for bigger studs..

The only plug and play heads are the R32 RB25DE heads.

[BoostdR]

Dipstick tube needs to be changed to the RB26 one as the rb30 is 35mm shorter. Or mark your rb26 Dipstick High level 35mm higher.

Rb30 water outlet that fits in the side of the thermostat housing is smaller in diameter than the rb26 and has an extra small port of the top. Rb26 one can be fitted. (taps out, press fit)

Oil filter thread need to be screwed out and replaced with the one from the rb26 block so the oil cooler, temp and pressure sensor can be fitted

Cam sprocket cover and needs to be widened if using an OS giken style idler pulley adaptor. Lower cover needs to be widened and extened to meet the top cover.

Rear block oil outlet(to head) needs to blocked off

Water pump bracket needs to be modified as the top bracket bolt goes to the block instead of the head now.

Fit your turbo oil return Tee before bolting the sump on.

lengthen front Diff breather hose 38mm.

When using ARP RB25 head bolts with 26 head. Extra washers may be required with a thin head gasket and shaved head as I ran out of thread.

Main girdle bolts. 3x long required extra washers. The long bolt in the center needs to be grinded shorter to clear the front drive shaft.

Don't forget to block the oil pressure outlet on the block under the rear knock sensor port off.

[bubba]

Water pump bracket needs to be modified as the top bracket bolt goes to the block instead of the head now.

Power steering pump.. not water pump.

[BoostdR]

Power steering pump.. not water pump.

thats the one!

[Althotas]

When using ARP RB25 head bolts with 26 head. Extra washers may be required with a thin head gasket and shaved head as I ran out of thread.

So whats the exact process with using the RB25 bolts with the 26 head, does anything need to be tapped etc?

I'll be using a standard thickness headgasket and stuff

Cheers

[jangles]

use stock 25 bolts, unless youre going all out. you can get the block tapped out to suit the 12mm studs that the 26 uses standard but it is not required.

RIPS one of the no doubt proven twin cam builders uses the smaller 11mm bolts.. they clamp down the heaad, the dowels locate it

Edited October 25, 2010 by jangles

[BIT SUS]

I haven't read it in this topic, but if I was to build a 30/26 for rwd use, what sump arrangement would be best? Would this eliminate the need for an adapter plate? And solve many bonnet clearance issues?

[rockabilly]

rb25 sump bolt straight on no adapter

bonnet issues yes in a 32 not a 33/34

[bubba]

Just have to remove (or bash flat) the crank scrapers at the rear of the sump otherwise the 30 crank will smash them to pieces.

[JonnoHR31]

or you can use the 30 sump if the block comes with one and you dont have a 25 one. my 25 sump wouldnt even sit in place with the scrapers, dunno how you'd manage to bolt it all up. and it fouled on the girdle, not the crank itself.

[bubba]

You'd be amazed at what some people are capable of.. that includes fitting things that don't fit

[bigjiz]

hey all im just about to start building a 30/26 but im worried i wont be able to get it roady for it, will i need a mod plate for it if so where can i get one from. i live in brissy

[33SOM]

hey all im just about to start building a 30/26 but im worried i wont be able to get it roady for it, will i need a mod plate for it if so where can i get one from. i live in brissy

Would like an answer to this

[Simonster]

Keep it registered while the engine is built. Then just notify old transport of the new motor with the new engine number.

Mine was a NSW registered car- so i had to get a roadworthy anyway- I didn't have any issues.

Depends if the guy doing it knows what it is. When he sees the extra pice between the block and sump you could say its just extra bracing.

[Marko R1]

Mine was also registered with the rb2630

[bigjiz]

But what about the extra capacity? wouldn't they be onto it when the block no. starts with rb30 not rb26?, i thought u would need it compliance for the engine conversion

[r32-25t]

What size oil restrictors are people using in their 30/26 I've got that back one block and a 1.5 in the front and can't seem to get enough oil to the head to feed the rear cam journal on the exhaust cam

[luke gtr]

What size oil restrictors are people using in their 30/26 I've got that back one block and a 1.5 in the front and can't seem to get enough oil to the head to feed the rear cam journal on the exhaust cam

doesnt sound right.

blocked gallery, or large cam clearances?

[r32-25t]

All been checked and checked, have a new idea if what it could be