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Drilling Into Rb25 Head While Head Is On 25/30. Ideas.


sriver killer
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Hey guys,

Just thought I would throw this up for discussion.

Looking at drilling and tapping a hole for a remote oil feed for the vct on a 25/30 as it currently does not have one (internal vct mod doesn't work)

The head is currently on the engine and in car and was thinking of doing it in car.

The best strategy that i have come up with so far is:

drilling into head. grease covered drills and taps to catch the majority of the alloy and using compressed air from the other side of the drill location.

Not a real ethic way of doing things, but I am entirely open to ideas

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how exactly did you do the internal mod? what size holes did you drill and exactly where did you drill them etc, how have you tested the solenoid? unless theres somehow not enough pressure it should work fine.

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how exactly did you do the internal mod? what size holes did you drill and exactly where did you drill them etc, how have you tested the solenoid? unless theres somehow not enough pressure it should work fine.

1.5mm(from memory) drill bit through the sealing wall of the brass bung.

Using a working solenoid and I can turn it on off via vipec.

I am 100 % sure its because of the lack of oil pressure due to recieving it from the lifter gallery

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I think you will have to remove the head (or maybe the whole engine) as you only need a tiny bit of swarf to block your oilways - or you could get fine particles circulating in your oil supply.

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I think you will have to remove the head (or maybe the whole engine) as you only need a tiny bit of swarf to block your oilways - or you could get fine particles circulating in your oil supply.

That is not an option. someone who has seen the insides of the of a 25 head does the oil return from the vct (when vct off) go directly to vct drain on side of head (2 bolt flange with metal return to sump)

not via anywhere else?

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yer as far as i know myne works fine, havent actually run it on the dyno with it plugged and unplugged but i havent noticed a lack of midrange at all.

from memory i drilled a 1.5mm hole through the plug then another 1.5mm through the top. and block feeds are 2 x 1.6mm with a standard 25 pump

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yer as far as i know myne works fine, havent actually run it on the dyno with it plugged and unplugged but i havent noticed a lack of midrange at all.

from memory i drilled a 1.5mm hole through the plug then another 1.5mm through the top. and block feeds are 2 x 1.6mm with a standard 25 pump

i don;t think anyone with a 30 bottom end notices a lack of midrange lol.

I've got a very similar setup. 1.5mm hole through brass bung. block feeds 2 X 1.5mm stock oil pump

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been trying to do alot of out of the box thinking to no avail. lol

ive spent a little bit of time to test and compare between my rb25/30 and 3 rb25's.

the 25/30 with internal vct mod does not pour as much oil out as the standard 25 setup (ive got 3 rb25's and they all push out more oil out of the vct solenoid plug when solenoid is removed

has anyone had a play with their inlet cam cam gear, is it possible to move the adjuster (for the cam advance) by hand?

i tried moving a spare cam gear that I had lying around and It was near impossible to budge it. this cam gear could be stuffed just a bit curious.

contemplating swapping over inlet cam gear over for a known working unit atm

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