RB Heads

[Shift_Down]

I was wonder if the RB 20;25;26 heads are interchangeable.?or is any of the internals are interchangeable.

I'm not sure if interchangeable should be spelled all in one word without any spaces, cause it's damn long,,,,, 15 letters:pface

[PROJECTRB240SX]

NONE OF THEM ARE WITHOUT MODIFICATION..... IF YOU WERE TO PUT A RB25DET HEAD ON A RB20 BLOCK YOU WOULD HAVE TO USE A RB25DET ECU AND WIRING HARNESS BECAUSE NOW IT IS BASICALLY AN UNDERSIZED RB25DET.THE RB20DET SHARES SIMILAR VALVETRAIN PARTS TO THE VG30DE/T. THE RB25 AND 26 ARE INDEPENDANT OF EVERYTHING ELSE AS FAR AS I CAN TELL.

[Shift_Down]

thanks guys, and cameron did you get my email about the motorset.?

[spec-u-later]

I don't what you guys just said, just please do not change your avitar shift-down.

[themadscientist]

the RB26 uses bigger headbolts so that's a snag to putting it on an RB25, they have the same bore though 86mm. RB20 heads bolt to a block with a 78mm bore so that's a no-go. the positioning on the head bolts is identical but if you wanted to say put the RB26 head on the RB20 you would have to either sleeve the heads bolt holes for the 20's bolts or drill and tap the 20 block's holes oversize to accept the 26's bolts. I had to do that to put a CA18DE head on the CA20 block, very chilling procedure with a Makita and a friggin handtap:eek: You would also have to weld up the chambers on the 25 and 26 head to match the 20's bore size. Pain in the butt but by no means impossible.

[gani]

hey mad im in the process of doing the ca18 head to ca20 block my question is can i just use arp head studs and not have to drill and tap for the stock head bolts and also im sure its possible to use the stock ca18 wiring harness for this hybrid since the head is all where the main wiring harness connects to. soory to hijack the thread but i just had to ask that.

[BlockHead]

None of the valvetrain parts from the RB25 and RB26 are interchangeable?? Even with little head modification?

[themadscientist]

I haven't tried it but I would ASSUME(note capitalization) you can transfer the 26's valvetrain in but only the complete set, solid lifters and hydraulic lifter cams don't like each other. If that's what you want Tomei makes solid lifters and cams for them.

[themadscientist]

hey mad im in the process of doing the ca18 head to ca20 block my question is can i just use arp head studs and not have to drill and tap for the stock head bolts and also im sure its possible to use the stock ca18 wiring harness for this hybrid since the head is all where the main wiring harness connects to. soory to hijack the thread but i just had to ask that.

Ok here's what I discovered with this.

The CA20 uses a smaller diameter headbolt than the CA18DEThe CA20 runs the treads up flush to the blocks deck. The CA18DE sinks the holes deeper and the treads don' start until several millimeters down into the hole, it's oversize above the threads.

The CA20 does not have an idler, the CA18DE does but there is a location on the 20 block that can be drilled and tapped for it.

The CA20 belt is shorter than the CA18 but, and here's the P.I.T.A. of it, the tooth profile on the belts are completely different. The CA20 is a flat cog whereas the CA18DE is a sloped tooth. The CA20 I used had a different sized crank that the CA18DE so you cannot just put the 18's crank gear on the 20 crank, you will have to have a custom one made. You will also have to get a custom length timing belt, I can't remember how many it was, maybe 155 teeth.

It's not impossible but it takes some extra steps

[rbsileighty]

Does anyone know if the other VG30DETT valvetrain parts, besides the springs, are compatable with the RB20?

[PROJECTRB240SX]

I THINK THE LIFTERS AND RETAINERS ARE ALSO COMPATIBLE.... BUT I'M NOT ENTIRELY SURE BECAUSE I HAVEN'T TRIED TO SWAP THEM, YET.

[gani]

thanks for the info man ill look yoou up wren this project is under way right now im just gathering parts.