Tomei poncan RB26 info

[Amaru]

Yet another question,

Tomei 260 in/ex 9.15mm lift camshafts for RB26 should be a direct bolt in and then you just adjust the clearances? There shouldnt be any machining work required? (keeping in mind the head has already been machined to take large lift camshafts).

Thanks

[Mik]

Yet another question,

Tomei 260 in/ex 9.15mm lift camshafts for RB26 should be a direct bolt in and then you just adjust the clearances? There shouldnt be any machining work required? (keeping in mind the head has already been machined to take large lift camshafts).

Thanks

I'm pretty sure they are designed to drop straight in. The head doesn't even need to be machined. Technically, if valve clearences were right before changing the cams, they should be right after you drop in the new cams too.

[cameron]

Valve Guide clearance:

The vale should be approx 15mm from valve guide hole into combustion chamber you can measure it by using a dial guage. - If thats what your were talking about ?

You'll proberly need to adjust the timing on a cam gear for the cams to work properly. The RB25 ones bolt up and are perfect with out adjusting but the RB26 do need adjusting with cam gear.

Dont forget the seals for the camshafts.

If you are installing the valves your self were safety glasses and gloves because the exhaust valves a filled with metal lic sodium and if exposed to eyes you can have eye dammage.

Jun

[The Alchemist]

you will almost certainly need to re-shim them depending on the age of the car and the wear on the original cam shafts. because there will be wear, you can't simply measure the clearences of the original cams then make the assumptions that when you fit the new ones that they will be the same. They almost certainly will not be.

You have to do a dummy fit with the new cams then check all clearences, calculate any shim adjustments you may need to make> get any new shims you may need as a result of your dummy run, dismantle dummy run and fit new shims then recheck. This is a very time consuming process that took me and a fully trained nissan A grade mechanic 2 weekends to complete. I needed 11 new shims and had them made in a machine shop and heat treated to 50 rockwell hardness. Was well worth the result though with the engine now running very smooth with no valve noise as start up like I used to get cos clearences are all perfect. Boost ramps up by 3500rpm now and pulls hard to 5000rpm were I am now having boost creep problems due to excessive back pressure from the now restrictive turbine. It can't handle the air flow the engines putting through now so I am going to remove the turboes and machines out the little GTR wastegate holes into big holes to help the exhaust escape and minimise backpressure.

So you see, cams are great but can cause other problems down the road. It seems the GTR was built to a certain spec and has limitations once you start pushing things along a bit ..

Mike

[pnblight]

poncam means bolt in in japanese and i fitting these cams in a matter of a few hours check all my clearances f.....g spot on the japans know how to make good gear ,the car ran 500 plus at the wheels and has run happierly ever sence, Amaru dont let these guys scare you it not like performing brain surgery and hope you enjoy the new cams god knows me rev210 are

[The Alchemist]

just trying to offer advice not scare people...this was MY experience only and YOU could have quite different results either better or worse for that matter...!

Mike

[Amaru]

pnblight thanks for that, they were put in and found out the clearances were all wrong for the camshaft, im putting that down to general wear and tear on the engine.

The Alchemist, thanks for the info, exactly what I was after

[rev210]

I put my cams in last night without a shim, checked clearences (spot on). My engine has more than 230,000kms as well (engine well serviced). Go Tomei poncams!!!

Base circle diameter is the same on both the factory cam and the tomei replacement this is the ONLY factor. If you need shims for the tomei you would have/should have needed them for the factory cams.

The 260deg 9.15mm lift units are mint !