Installing Cams In Rb26

[Chris32R]

I'm going to be installing a pair of 9.7mm 272 camshafts and HKS cam gears in my RB26 soon. Just wanted to know if there is any tips or advice on how I should tackle this? I've read about people doing a cam swap without completely taking the timing belt off. How can this be done?

What parts (gaskets,seals, etc..) should I replace whilst I have everything apart? The head has been rebuilt (still to standard specs) and has HKS Step 2 valve springs already instalkled.

Thanks

Edited January 3, 2011 by Chris32R

[Adriano]

You can do the cam swap without removing the belt, you need to remove the cas bracket, and cabletie the cam belt to the camwheels. support the gears so they dont frop. Make sure you sneak the cams down gently and evenly or the cam canbe snapped. I do the cam swap with the motor about 20degrees before top dead centre. Might as well replace the valve cover seals at the same time if you havent already done so.

[Chris32R]

Ok to make sure that i got this right. First thing to do is remove Cas bracket. Turn the motor to 20 degrees before TDC (I thought it was easier to have it lined up right on TDC?). Cable tie cam gears to timing belt and support cam gears so that they don't fall. Undo and carefully slide both cam gears evenly off the camshafts. The rest of the process is just slowly and evenly undoing the cam caps starting from the middle and working your way out. Remove cam. Lubricate the new cam lobes, cam buckets, lifters and journals. Install new cam and slowly tighten cam caps starting in the middle working your way outwards.Install new cam seals. Replace the old cam gears with your new ones making sure that they are in the same position as the old ones. Install cam gears. The rest of the process is pretty self explanatory.

Am I on the right track? Anyone know the torque rating that I should torque everything to?

Edited January 3, 2011 by Chris32R

[boostn0199]

If its your first time doing a cam change then I would recomend doing it by taking off the belt. If your not familar with doing it without taking the belt off it might turn into more of a hassle then hoped for. But then again guess you wont learn how to do it until you have a go/

[GTRNUR]

I hope the head was clearanced for the high lift cams when it was rebuilt because 9.7mm lift cams will not fit an un-clearanced head. I recommend removing the belt as well. So radiator out, fan off, harmonic balancer off, bottom cover off. Align your timing marks on the oil pump and cam backing covers and then work the service manual.

The service manual contains all the torque specs you will need, and you definatly should not be attempting this if you dont have a copy of it. Its also worth considering changing your idler and tensioner bolts with new ones, and possibly the bearings themselves if they are aged.

Always torque exactly to spec as well.

Remember RB26's are interference engines, and it will end in tears if you dont do it 100% correct!

[Chris32R]

I hope the head was clearanced for the high lift cams when it was rebuilt because 9.7mm lift cams will not fit an un-clearanced head. I recommend removing the belt as well. So radiator out, fan off, harmonic balancer off, bottom cover off. Align your timing marks on the oil pump and cam backing covers and then work the service manual.

The service manual contains all the torque specs you will need, and you definatly should not be attempting this if you dont have a copy of it. Its also worth considering changing your idler and tensioner bolts with new ones, and possibly the bearings themselves if they are aged.

Always torque exactly to spec as well.

Remember RB26's are interference engines, and it will end in tears if you dont do it 100% correct!

I beleive the 9.7mm cams I've got are the biggest lift cams made that could fit in an unmodified head. Yep I've just downloaded the service manual and yeah I always torque every bolt that i can up to the required spec. I'm very fussy when it comes to my cars .

Where can the idler and tensioner bolts be purchased from?

Thanks for the help.

[GTRNUR]

I beleive the 9.7mm cams I've got are the biggest lift cams made that could fit in an unmodified head. Yep I've just downloaded the service manual and yeah I always torque every bolt that i can up to the required spec. I'm very fussy when it comes to my cars .

Where can the idler and tensioner bolts be purchased from?

Thanks for the help.

Get the idler bolt and tensioner stud from Nissan. Use genuine parts only.

I think you want to double check that cam clearance too. I know the JUN cams of the same lift use a smaller base circle to get more lift at the lobe, so you can also count on needing a complete set of custom bucket shimms too.

[Chris32R]

Get the idler bolt and tensioner stud from Nissan. Use genuine parts only.

I think you want to double check that cam clearance too. I know the JUN cams of the same lift use a smaller base circle to get more lift at the lobe, so you can also count on needing a complete set of custom bucket shimms too.

Ok thatnks.

Yeah the cams are Jun 272 9.7mm lift on both intake and exhaust. So now do I need shims when I install them? Hmmm this is starting to sound very complicated. I thought the Jun cams would just drop straight in and nothing else would be needed except new seals, gaskets, etc...?

Edited January 3, 2011 by Chris32R

[GTRNUR]

Ok thatnks.

Yeah the cams are Jun 272 9.7mm lift on both intake and exhaust. So now do I need shims when I install them? Hmmm this is starting to sound very complicated. I thought the Jun cams would just drop straight in and nothing else would be needed? except new seals, gaskets, etc...

To install them properly you do a trial fit with no shimms installed. You then need to measure the distance between when the cam bucket and the cam at 0 lift so you can work out what thickness of bucket shim to use. You have to rotate the engine over by hand with both the cams installed when doing this, so you can measure from the middle of the back of the lobe to the cam bucket.

Once you know your cam clearances for all 24 valves you can order the appropriate thickness shims. Jun cams use a recommended 0.3mm intake and 0.33mm exhaust clearance. There is a few tricks when installing them too, such as using wet and dry paper to trim the shims up precicely, and also to take the sharp edges off the machined edge of the shim, so that it fits better into the back of the bucket.

The importance of getting this right makes the difference between having an optimal setup, having a less than optimal setup that is noisy like a tractor, or having a valve not seal against the seat which will result in a burnt valve seat and head damage or worse.

[boostn0199]

Get the idler bolt and tensioner stud from Nissan. Use genuine parts only.

I think you want to double check that cam clearance too. I know the JUN cams of the same lift use a smaller base circle to get more lift at the lobe, so you can also count on needing a complete set of custom bucket shimms too.

Just a question while on the topic, do you use loctite on the tensioner stud when changing it?

[Don Dada]

What do you guys use to hold the cam gear in place to slacken/ tighten if changing gears alone without taking off the valve covers?

Any tricks?

Chris...youre suppose to slacken the caps from the outside to the inside when removing

Edited January 4, 2011 by Don Dada

[choyda]

To install them properly you do a trial fit with no shimms installed. You then need to measure the distance between when the cam bucket and the cam at 0 lift so you can work out what thickness of bucket shim to use. You have to rotate the engine over by hand with both the cams installed when doing this, so you can measure from the middle of the back of the lobe to the cam bucket.

Once you know your cam clearances for all 24 valves you can order the appropriate thickness shims. Jun cams use a recommended 0.3mm intake and 0.33mm exhaust clearance. There is a few tricks when installing them too, such as using wet and dry paper to trim the shims up precicely, and also to take the sharp edges off the machined edge of the shim, so that it fits better into the back of the bucket.

The importance of getting this right makes the difference between having an optimal setup, having a less than optimal setup that is noisy like a tractor, or having a valve not seal against the seat which will result in a burnt valve seat and head damage or worse.

I have the same cams 272 9.7mm. Shims were required. Dan from ERD did all the work of measuring and ordering the right sizes.

[GTRNUR]

Just a question while on the topic, do you use loctite on the tensioner stud when changing it?

Light grade on the end of the stud that goes into the block, and on the idler bolt thread. The wavey locking washer under the nut and the correct torque spec for tightening the nut do the rest.

Nissan know what they are doing when they design these things so there is no need to over think, or try and over engineer something that is already thouraghy tested, designed and approved by teams of engineers. Everything you need to know is in the manual.