Ignition Timing Question, Rb30/25De + Turbo.

[nicksamaniac]

Hi all, I've built myself up an rb30 bottom end with an r32 rb25de head and running it with r33 rb25det harness and ecu @8psi. (soon to be power enterprise 800cc injectors and power fc)

All is good and it runs like a clock, but when I try to check timing via light and balancer marks it's miles off?

I've just set the timing at its original spot (where it's cas witness marks were on the rubber seal/timing cover)

And have spoken to 2 tuners and they've both had the same problem?

I measured the 30 balancer and is identical to the 25 balancer (bar the belt type)

Anybody had same or similar experiences?

[Ben C34]

How are you using the light? if you use the wire loop it results in an inaccurate reading.

You should disconnect a coil and put a lead on it to the plug, then clip the light on there.

Also, due to differences in the deck height etc the cas position won't be the same as the 25 position, meaning the cams would also be out slightly.

Edited February 8, 2014 by superben

[89CAL]

Also, have you disconnected the TPS or AAC valve (can't remember which you disconnect on RB25) to put it into base timing mode. If its miles out this probably wont be the issue but google it or grab a shop manual to check it out

[nicksamaniac]

Yeah I use the loop for pickup, and disconnect the aac and throttle switch,

Thanks superben, but I need to clear this up -

Deck height will make no difference at all, this is basic engineering- rules of ratio never change regardless of drive length,

this is the 1st thing everyone has said to me, and it needs to be known!

if it had 800cm extra deck it will still be the same ratios at the cam gears.

Why will The loop wire give false readings? Isn't that the 1st coil anyway?

The only ideas I can come up with is the light I have doesn't like the dwell time or is the wrong ct pickup for the system?

(as in hysteresis collapse vs inductance)

and that in the manual it says to put consult on and put it into test/tune check mode? Then check timing with the aac and tvs unplugged.

Also when I say miles off, I mean about 35'retarded past 0' at the balancer, if I try move it to 0' it runs like a dog nearly stalls etc, same if I move it the other way, it's like it works 100% at the cas (does its job), but the balancer tells a lie!

Google hasn't helped me much, that's why I'm on here.

Edited February 8, 2014 by nicksamaniac

[XKLABA]

Yeah I use the loop for pickup, and disconnect the aac and throttle switch,

Thanks superben, but I need to clear this up -

Deck height will make no difference at all, this is basic engineering- rules of ratio never change regardless of drive length, right, as long as when you set the cam timing the marks lined up perfectly then the timing would be right or at least very close

this is the 1st thing everyone has said to me, and it needs to be known!

if it had 800cm extra deck it will still be the same ratios at the cam gears. yep the crank will always spin 2 times to the cam shafts one due to the timing belt gears being the same

Why will The loop wire give false readings? Isn't that the 1st coil anyway? good question, personally I'm not sure but I have seen it do it, I just open the timing light hook and hold it against the front of number one coil

The only ideas I can come up with is the light I have doesn't like the dwell time or is the wrong ct pickup for the system?

(as in hysteresis collapse vs inductance)

and that in the manual it says to put consult on and put it into test/tune check mode? Then check timing with the aac and tvs unplugged. if that is what the manual says then that would what you try

Also when I say miles off, I mean about 35'retarded past 0' at the balancer, if I try move it to 0' it runs like a dog nearly stalls etc, same if I move it the other way, it's like it works 100% at the cas (does its job), but the balancer tells a lie!

Google hasn't helped me much, that's why I'm on here. are you using the right markings ? in the right order, 35 deg is a long way off, try checking the timing directly off number one coil and see if that helps, I've only seen the timing out upto 10 deg from the loop

[Ben C34]

The deck height changes the position of the cams and therefore cas. When you lift or lower the head, the cams have to rotate to maintain the same belt length on the drive side (imagine doing that with the tensioner loose, it makes more sense.)

I seriously doubt an rb30 block works out perfectly the right extra deck height to work wit the belt. it is very close, but slightly different so will need adjustment.

disconnect tps on a neo to put it ibto base timing mode, not sure pre neo.

Dont know why the loop sucks, but it does. a normal plug lead will work between the coil and will be accurate.

[XKLABA]

That's why I said, if the timing marks line up perfect then the cam timing is perfect, which mine is, if not then you would have to adjust for it, though it certainly wouldn't be 35deg out if the markings are close, at worst they can only be up to half a tooth out one way or the other

[nicksamaniac]

When I built the motor i used standard timing covers and just cut and welded extra bits to fill the gaps, so the back plate marks are stock to the head and the oil pump notch is still the same.

As its a modified engine I didn't have a tooth count to set the cam belt so I just went off the marks.

rotated the crank about a zillion times (to make very sure) and on every 2nd revolution they all lined up at zero again so I know it's on the money.

Ill have to hook up the consult tx-rx wires to a diagnostic port, cos this is in a patrol and it never had one!

But first I'll try a plug lead.

Cheers guys for the help so far!

[nicksamaniac]

The deck height changes the position of the cams and therefore cas. When you lift or lower the head, the cams have to rotate to maintain the same belt length on the drive side (imagine doing that with the tensioner loose, it makes more sense.)

I seriously doubt an rb30 block works out perfectly the right extra deck height to work wit the belt. it is very close, but slightly different so will need adjustment.

disconnect tps on a neo to put it ibto base timing mode, not sure pre neo.

Dont know why the loop sucks, but it does. a normal plug lead will work between the coil and will be accurate.

I do understand what your saying about deck height, but that only really applies if you moved the head (say 1mm to a 3mm head gasket) and use the same belt and tooth count.

But I'm using an aftermarket belt, (gates custom length something number?)

to suit rb30det mod. And this adjusts the tooth count to compensate for deck height.

[GTRPSI]

Pull the plug out of cylinder #1 and put a long coat hanger wire down the hole to the piston so you can feel it.

Get someone to rotate the engine to top dead center, when the piston is at its highest, find the pistons highest point in its travel by feeling when the wire is at its highest position.

Check to see if the harmonic balancer mark lines up with the cover marking, This is your top dead center point.

If not the outer ring may have slipped or your keyway may be worn, crank bolts are known to get loose and damage keyways.

Assuming the factory markings are out, the bolts not loose and the keyway is fine, put a new mark on the balancer with liquid paper and try the timing again, see if its still off with the new markings.

Edited February 9, 2014 by GTRPSI

[nicksamaniac]

Tdc was checked with a dial indicator when the engine was assembled, cam timing setup was done this way as part of the whole not knowing the tooth count,

the engine is freshly built, the key and balancer are good.

Initially I thought maybe the 30 balancer had a different key position to the 25 balancer.

But as I mentioned earlier they are the same apart from belt type. The key position and marks line up when you stack them on top of each other.

When its at tdc on #1 the 0' lines up with the timing cover.

Edited February 10, 2014 by nicksamaniac