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Rb30/26 Head Studs? Help Please

SJR

By SJR,
in Engines & Forced Induction

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SJR Apprentice

SJR

Posted
Posted

hi,

iv built a Rb30 bottom end with a RB26 head, RB26 head studs have a different diameter and RB30 head studs are two long..

what is the best option?

do you drill n tapp the block? or helicoil or what??

also timing belts...i think we are relocating the tentioner. what size do you need? iv read 152 teeth, but is this 100%? does anyone hav any info that could help me out?? this car has been off the road for a year now n im really keen on getting my engine it.. would be greatly appreciated

thanks

phone number: 0416 53 58 50 or reply

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R.I.P.S NZ
R.I.P.S NZ

You 'could' tap the block to 12mm but from experience I can tell you it its perfectly fine to run 11mm RB25 head studs with a 26 head. I've done alot of miles and drags with a best of 8.71 @ 162 with

Alf
Alf

I used ARP Rb26 head studs on my 25/30. Apart from drill and tapping the block the 25 head had to be drilled out to suit the larger head studs. I used the 26 studs as they were cheaper and available

JH32
JH32

Ah cool, cheers guys

dat16dog Contributor

dat16dog

Posted
Posted
hi,

iv built a Rb30 bottom end with a RB26 head, RB26 head studs have a different diameter and RB30 head studs are two long..

what is the best option?

do you drill n tapp the block? or helicoil or what??

also timing belts...i think we are relocating the tentioner. what size do you need? iv read 152 teeth, but is this 100%? does anyone hav any info that could help me out?? this car has been off the road for a year now n im really keen on getting my engine it.. would be greatly appreciated

thanks

phone number: 0416 53 58 50 or reply

Drill and tap the block

Justjap in Sydney ( i think) keeps the belts in stock for RB 26/30 conversions. seen em advertized with other retailers aswell.

Martin HKS Enthusiast

Martin HKS

Posted
Posted
Drill and tap the block

Justjap in Sydney ( i think) keeps the belts in stock for RB 26/30 conversions. seen em advertized with other retailers aswell.

You can't drill and tap the block from 11mm to 12mm! The thread will never clean up. You can helicoil it. I'm not sure what others have done.

Cheers

Marty

Adriano Grand Master

Adriano

Posted
Posted

You certainly can drill and tap the thread. You need to drill to 10.5mm, and drill the recess at the top of the hole to 12mm(this is vital) then tap the holes to M12 x 1.5. The new thread will follow the old thread. Another easier option (especially if the motor is assembled) is to use rb25 head studs, they are the correct thread for the rb30 block and the correct length for the rb26 head, you must ensure the 2 dowels are in though.

152 teeth is correct depending on the location of the second tensioner.

(low and high)

Martin HKS Enthusiast

Martin HKS

Posted
Posted
You certainly can drill and tap the thread. You need to drill to 10.5mm, and drill the recess at the top of the hole to 12mm(this is vital) then tap the holes to M12 x 1.5. The new thread will follow the old thread. Another easier option (especially if the motor is assembled) is to use rb25 head studs, they are the correct thread for the rb30 block and the correct length for the rb26 head, you must ensure the 2 dowels are in though.

I don't have a thread chart in front of me to check but I wouldn't have thought you could get the 11mm to clean up nicely to tap 12mm. As long as they chase the pitch correctly when tapping I guess you can do it. I would probably save the headache and use the RB25 head studs. That way it also stops the flimsy RB30 deck from warping when you try clamping down the 12mm studs to 85 foot pound.

Cheers

Marty

shanef Grand Master

shanef

Posted
Posted

i personally wouldnt re-tap the thread for the bigger studs. i'd use rb25 studs. the more thickness u can leave in the block the better

as martin said. ~0.75mm isn't ideal to cut a new thread in, however that said ppl have re-cut them without any dramas.

  • 2 weeks later...
ahh 33 s2 Mentor

ahh 33 s2

Posted
Posted
With over 40 x RB30's built since 1999, I would always use ARP (RB26) head studs.

Cheers

Gary

gary have you used a similar method as adriano has explained?? or can you recomend a different approach to the process

R.I.P.S NZ Collaborator

R.I.P.S NZ

Posted
Posted

You 'could' tap the block to 12mm but from experience I can tell you it its perfectly fine to run 11mm RB25 head studs with a 26 head.

I've done alot of miles and drags with a best of 8.71 @ 162 with 11mm studs, over 1000hp, never had a problem.

Rob

  • Like 2
2BNVS Veteran

2BNVS

Posted
Posted

i use 1/2" arp head studs in my 26/30, my machiner actually got them from a US car i have to ask him again for the exact details, lucky as he deals with the old school muscle cars just as much as jap cars they were perfect length

ben...

Martin HKS Enthusiast

Martin HKS

Posted
Posted
i use 1/2" arp head studs in my 26/30, my machiner actually got them from a US car i have to ask him again for the exact details, lucky as he deals with the old school muscle cars just as much as jap cars they were perfect length

ben...

In our experience using 1/2 inch studs in the RB30 block cause the deck to distort when torqued as you need to be around 100 foot pound. The RB30 has a thinner deck than it's little brothers (RB25/26) and the largest size we have sucessfully seen is 12mm (slightly smaller than 1/2 inch). For ease of fitment the RB25 work fine.

Cheers

Marty

  • 2 months later...
  • 4 years later...
sultanaz Proficient

sultanaz

Posted
Posted

Can i please ask if anyone has ever had a drama with using rb25 arp head studs in a RB26/30.
And if you havent had any dramas what power and boost were you running with the 25studs.

Wish my builder told me about this before we got 3/4 through building the engine... im abit worried about running the rb25 head studs..

Only gna be running around 26psi or so through GT-SS with larger rear housings on e85 and higher com, type b poncams, ported etc etc..

Should be around the 400kw flat mark if im lucky....

But im kind of pissed off because i have ibeam rods and what not now i feel like the rb25 head studs is my weakest link ! :@
Now if i want to go a single or something in the future im gna feel like its just gna pop.

Ben C34 Grand Master

Ben C34

Posted
Posted

Can i please ask if anyone has ever had a drama with using rb25 arp head studs in a RB26/30.

And if you havent had any dramas what power and boost were you running with the 25studs.

Wish my builder told me about this before we got 3/4 through building the engine... im abit worried about running the rb25 head studs..

Only gna be running around 26psi or so through GT-SS with larger rear housings on e85 and higher com, type b poncams, ported etc etc..

Should be around the 400kw flat mark if im lucky....

But im kind of pissed off because i have ibeam rods and what not now i feel like the rb25 head studs is my weakest link ! :@

Now if i want to go a single or something in the future im gna feel like its just gna pop.

Read the post by rips a few up. I wouldn't worry at all about using rb25 head studs.

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