Oil Restrictors

[moogley]

hi all iv been building a rb30/25 ,no vct , and running a n1 oil pump , am i right to assume i should be running 2x 1 mm oil restrictors , any help will be appreciated

Edited September 15, 2010 by moogley

[Al]

I have tried 1mm and 1.5mm, also using an N1 oil pump, both cases left me with a noisy head, on idle. Now i am ripping the restrictions out and running the std 2mm. Hopefully that would make it sound normal again.

Just my experience

PS: Any revs above 1000rpm, and the head sounded perfect/normal. Pulled down the head and found no wear on lifters or cams; after 10,000km.

[jarrod83]

doesnt the rb25 have 2x1.5mm restrictors standard tho? im running the 2x2mm standard rb30 ones atm.. and my heads swimming in oil , thinking of dropping down to 2x1.3mm

[moogley]

according to a build guide i have rb30s have 2x1.8mm restrictors as standard and rb25s have 2x1.5 standard but it recomends to use 2x1mm?

[Dale FZ1]

I have tried 1mm and 1.5mm, also using an N1 oil pump, both cases left me with a noisy head, on idle. Now i am ripping the restrictions out and running the std 2mm. Hopefully that would make it sound normal again.

Just my experience

PS: Any revs above 1000rpm, and the head sounded perfect/normal. Pulled down the head and found no wear on lifters or cams; after 10,000km.

according to a build guide i have rb30s have 2x1.8mm restrictors as standard and rb25s have 2x1.5 standard but it recomends to use 2x1mm?

Moogley you've seen the man's advice. It's a fairly common experience - the issue is obtaining sufficient flow from the pump at low revs (idle) through a small orifice to fill the hydraulic lifters.

I have a stock pump with 2mm shim, and 2x 1.6mm feeds and no VCT. Hot or cold start it takes ~ 2-3 secs to pump up the lifters and otherwise the top end is silent at any engine speed. I expect it and can live with it

The other thing I found was a big impact by the grade of oil used on cold start oil pressure and lifter noise. The guide is just that, not a Bible. If you're 100% road use then stick with the stock feeds to avoid noisy lifters. But do drill out the internal oil returns in the block and head.

[moogley]

thanks for the advice every1 it helps alot , i just dont wanna kill my new engine with something that could have been avoided

[Dale FZ1]

I don't think you're likely to kill the engine by using the smaller restrictors, but noisy lifters at idle would be a PITA over the long run.