Rb26 Gtr Camtiming... Setting Up The Cams And The Timing Belt

[skylinerun]

i am just fitting some tomei poncams...

is it

10o clock intake, 2 o clock exhaust

however, how many links inbetween the two?? and how do you do Rb26 cas timing also? im not sure.. ive only really done sr20's and commodore cam swap/timing .

any help would be much appreciatd.

thx

[shaund]

There are timing marks for both cams (dots on the black plate behind the cams) that you need to line up with the 'dots' (drilled out small marker holes) on the cam gears.

Likewise on the crank, there is a drilled out 'dot' on the timing belt gear on the crank, and a notch cut out of part of the oil pump housing. Just make usre these are all lined up 100% perfectly before you take the belt off.

As for the number of notches between cam gears, its just really 'tight'. I rotated one of the gears towards the other so it was easier to get the belt on, and then 'tightened' it up by rotating the cam gear back.. was only a couple of mm required to make it easier to get the belt on. Also helps if you have 1 or 2 more people there to help hold the belt in place so it dosen't slip off

CAS timing is easy. Base timing is 20 degrees. Check the manual for more details, but there is a loop at the rear of the engine at the top for an inductive pickup timing light. Rotate the housing of the CAS to get your base timing right. Do it with the engine off, a bit at a time. Each mark on the harmonic balancer equates to 5 degrees BTDC, and if memory serves the mark all the way on the right side is 30 degrees. Check the manual though.

I recently put poncam Bs in my 32GTR, and the power gains are well worth the expense!

Good luck and have fun

i am just fitting some tomei poncams...

is it

10o clock intake, 2 o clock exhaust

however, how many links inbetween the two?? and how do you do Rb26 cas timing also? im not sure.. ive only really done sr20's and commodore cam swap/timing .

any help would be much appreciatd.

thx

Edited March 16, 2009 by shaund

[skylinerun]

Thanks dude.

i did this it works fine, i thought i bent a valve or something as the car is idling too lumpy

i think my CAS is out

ill give it a shot

thanks so much

[shaund]

if its *really* lumpy, it may be that one of your cams is out by a tooth, which IIRC, can be about 10 crank degrees or more!

Given that you're harmonic balancer is back on, you can get TDC from the timing marks on the harmonic balancer, and just take the cam cover off to get things lined up.

I can't remember if there is infact a 0 degrees mark on the harmonic balancer. If theres not, you can have a bit of an estimate. perhaps add some marks yourself. check the manual.

Use a short straight edge to see if the dots on your cam gears are perfectly lined up, and to check the timing mark, im pretty sure you wanna look across the mark

on the timing belt cover 'through' the centre of the crank shaft if you know what i mean.

I also found that the plate behind the cam gears was a little cock-eyed... one cam was slight above, the other was slightly below after re-fitting the timing belt.

Its quite possible that its the CAS needing adjustment, but you'll need a timing light for that anyway. I found 20 degrees on mine was with the CAS pretty much dead centre on the adjustment. a few degrees either side of that shouldn't make your idle overly lumpy though.

My idle is only slightly more lumpy than factory with poncam Bs and no advance/retard on either cam. I'm yet to dial that in... need some dyno time

Out of interest, did you replace your idler and tensioner bearings for the timing belt?

[R33GTRKid]

Xspeed are dialing my pon b's in next wednesday, ill flick up the settings once he has done it and end power result, currently sitting on 431 rwhp on 0,0.