Rb30 Arp 12mm Stud Problem Help..

[rockabilly]

right guys my rb26/30 is well under way. had the block cleaned and dipped, new welsh plugs, decked, bored for the cp,s .35, stud drillled for cam tensioner and 2 holes drilled for knock sensors. asked the engine shop to drill my block,to take my rb26 arp studs. they said it was to close to drill and said it would need to be helicoiled. can anyone who has actually fitted and rb26 head on an rb30 using the 26 head studs tell me the best way to go..thanks bernie/uk

p.s also got my crank back polished and proengines collar fitted. it was also balanced with the 26 front pulley, rb25 crank bolt and flywheel. guy said it was 10 grams out, seems to be centre main web and front pulley that needed drilling to balance it up..

Edited August 11, 2007 by rockabilly

[Scooby]

  rockabilly said:

right guys my rb26/30 is well under way. had the block cleaned and dipped, new welsh plugs, decked, bored for the cp,s .35, stud drillled for cam tensioner and 2 holes drilled for knock sensors. asked the engine shop to drill my block,to take my rb26 arp studs. they said it was to close to drill and said it would need to be helicoiled. can anyone who has actually fitted and rb26 head on an rb30 using the 26 head studs tell me the best way to go..thanks bernie/uk

p.s also got my crank back polished and proengines collar fitted. it was also balanced with the 26 front pulley, rb25 crank bolt and flywheel. guy said it was 10 grams out, seems to be centre main web and front pulley that needed drilling to balnace it up..

when Proengines did mine it was drilled. that said, it's quite a fiddly job to get everything lined up correctly. also could it be that the machine shop hasn't measured the existing hole and studs and is making assumptions about the sizes?

Edited August 10, 2007 by Scooby

[T04GTR]

do not helicoil them.

you have to drill it. in a propper mill. then retap for 12mm (11mm standard rb30) its not a total retap. just making it abit bigger as there the same pitch.

[Adriano]

  T04GTR said:

do not helicoil them.

you have to drill it. in a propper mill. then retap for 12mm (11mm standard rb30) its not a total retap. just making it abit bigger as there the same pitch.

Thats what i would do, i had my machine shop do it, and am not very impressed with the end result. I would also recommend drilling the top part of the hole that has no thread to 12mm, so when the tap is put in, it alignes to the threads already in the block, not start a thread at the top, as it wont line up with the existing threads once you get down to them(if that makes sense)

[T04GTR]

yeah. exactly. hense why it needs to be drilled squarly.

[rockabilly]

cheers guys will do..

[proengines]

Theres no problem taking the threads out to 12mm. You are going from 11 to 12mm at the same pitch. I redrill the counterbore first, then drill the centre of the thread to the tapping drill size for a 12mm thread. When you tap the thread, you have to make sure that you catch the tap in the original thread or you will end up with a mess rather than a thread. I do it all in the mill, it keeps it straight and square.

If they do it in the mill, they will need to pop it into neutral on the spindle to get the tap started, then engage it and cut the thread. Using a HSS tap, its no problem to power tap it using the mill.

I do the whole process on one bolt hole at a time, it's a bit slower because you are constantly changing tooling but it keeps everything aligned spot on.

There's no problem helicoiling them if they need it.

[rockabilly]

cheers greg.