4age Camshaft Timing

[Stain]

I've rebuilt a 4AGE smallport, got it installed and running.
Now I want to get the most out of my after market camshafts.
But I'm just not sure how to go about timing them precisely.

From what I've read, I need a timing disc (bolted to the crank shaft)
with a pointer (bit of wire?) to find TDC using a dail guage down cylinder #1.

Now at TDC the intake and exhaust lobes over #1 should be pointing at each other?
And when I turn the crank over by 110deg clockwise, the intake valves should be fully open.
And then the crank gets turned over by 110deg anti-clockwise from TDC and the exhaust valves should be fully open.

Okay so here is where I'm lost... Where does 110deg come from? Why is that the figure we're looking for?
What happens if the valves arent completely open, or have started to close at this 110deg mark?
Is this where adjustable cam gears come into play to rotate the camshafts so the valves are fully open?


If it helps.. the cams are HKS 256deg 8.1mm lift, the head has been shaved and I'm running a thinner headgasket.

[fixeruperer]

its a pretty hard process to teach someone over the net/phone, try to get someone to show ya in person.

but here is a pretty easy process to time lobe centers @ 40" :
http://www.skylinesaustralia.com/for...s-t240804.html

[30psi 4agte]

Do you have adjustable gears?

You will only beable to check the timing if you dont have em.

[mullett]

if you've got cams in your 4AGE, I'd be getting adjustable cam gears ASAP. Different cam, but I had WADEs in mine, and there was 30hp adjusting the cam gears...it ran like a DOG before we played with them, originally they were installed with the factory cam gears and factory timing.

-RM.

[oldeskewltoy]

to answer your questions... you are looking at crankshaft degrees when you dial in the camshafts.

The degree wheel is set to TDC... BUT that is JUST to make sure you know TDC... once it is known and set on the degree wheel/wire... TDC is just one point of 360 degrees.........


You will need adjustable timing PULLEYS to adjust camshaft timing. To show you how close timing is....





Above is a T3 timing gear... I've added 2 scratch marks... the one on the left, highlighted by the yellow arrow, when the scratch mark, and the end hash mark are aligned = 111 degrees of cam timing... The scratch mark on the right, highlighted with the red arrow, when the hash mark and scratch mark are aligned = 108 degrees of cam timing.

Now if you checked out cam timing for 4AG engines, you'll remember stock cams run SMOOOTHLY at about 111 degrees. Performance camshafts... are frequently set between 108 and 105, lower for more aggressive higher rpm operation

Look at how small the difference is between 108... and 111. Small adjustments make a WORLD of difference!!!!

[Stain]

I've got adjustable pulleys and I understand how to use the dail guage to make sure the valves are fully open. But what I just dont understand is what point on the degree wheel should they be set to fully open?

Most sites/guides say anywhere between 100-120 after TDC. Is there no way of working out what position would best suit a particualar cam?

[oldeskewltoy]

But what I just dont understand is what point on the degree wheel should they be set to fully open?

Most sites/guides say anywhere between 100-120 after TDC. Is there no way of working out what position would best suit a particualar cam?

cam card is your friend....... Whose cams???

[Stain]

HKS 256deg 8.1mm lift for both IN/EX. I bought them second hand so have nothing to go on but that

[oldcorollas]

I've got adjustable pulleys and I understand how to use the dail guage to make sure the valves are fully open. But what I just dont understand is what point on the degree wheel should they be set to fully open?
Most sites/guides say anywhere between 100-120 after TDC. Is there no way of working out what position would best suit a particualar cam?

it depends on many things. ie where you WANT the power to be in the rev range, how much overlap you want etc.
there is no single BEST position, as you change the intake and exhaust cam timing to move the power around.

1 Now at TDC the intake and exhaust lobes over #1 should be pointing at each other?
2 And when I turn the crank over by 110deg clockwise, the intake valves should be fully open.
3 And then the crank gets turned over by 110deg anti-clockwise from TDC and the exhaust valves should be fully open.

1, yes, cos the exhaust is closing, and the intake is just opening.
2. so the timing of the intake valve to fully open is 110deg ATDC
3. so the timing of the exhaust valve to fully open is 110deg BTDC



here is camcard for 2jz.. suplah but different cam
http://www.bobandapril.com/gallery2/...akecamcard.jpg

and

more random info
http://www.mr2supercharger.com/cams.html
TRD want 98-102?
http://www.mr2supercharger.com/4AGECamspecs.html
http://www.toymods.net/forums/archiv...hp/t-4547.html

[oldcorollas]

annnd from bills page
http://www.billzilla.org/4agmods2.htm

Cam timing
On the preceding page, I've talked about such-and-such a camshaft duration, but I didn't mention the actual timing of the cam that should be used. Everyone talks about having a cam of, say, 304°, but the one thing that's very important that they're missing out on is just where to put the 'top of the lobe', as this is the real trick to getting the best power out of your cams & engine.
And fortunately, it's dead easy to do!
The one simple rule that you have to follow is this - For cams with a duration of under about 270°, you want the cam lobes to be at about 110-110, and above about 270° have the lobe centres at about 100-100.
(note that this is a general rule, and each engine will require fine tuning to get the last little bit out of it, but the actual figures will almost invariably be to within 2° or maybe 3° of those numbers, eg, 100-100 may up ending being 98-102, and 110-110 being 108-113)

So what do I mean by 110-110 and 100-100?
Again, quite simple to do - With the engine at Top Dead Centre (TDC) #1 or #4 cylinder, and what you are looking for is to have the inlet cam lobes for #1 cylinder just starting to open, ie, the cam lobes on #1 cylinder must be pointing towards each other. If you wind the crank over 110° in the forwards direction, then the inlet valves should be fully open. This is checked by means of a dial vernier gauge, which can accurately and repeatably measure valve lifts to less than 0.001".
To check the exhaust timing, simply wind the engine backwards from TDC #1 by 110° (or 100° as the case may be)
If you haven't done cam timing like this before it may seem a tad difficult, but it only takes a few tools, a bit of patience, and some time. Note that it must be done as accurately as possible, because a 'degree or two here or there' just isn't good enough!

however, since the change in lift is smallest and slowest at full lift, it can be better to assume a symmetrical lobe, and use a certain lift measurement to find the centre..

and FWIW, it is best to set up on dyno.
change the timing of each cam, 1 step at a time, and see what works best where YOU want it to..

[oldeskewltoy]

I happen to have the cam cards for the "newer" 4AG HKS cams..... you said 8.1mm???

The original HKS 4AG cams were 8.35 lift... the new ones are 8.0

exhaust....



Intake...

[Stain]

Oooo. Thanks for that. Makes an excellent starting point.

[merc-blue]

your going to need some specalised tools to do it.
When your talking about 1 degree you need to know your TDC measurement is accurate. and im talking more accurate than a dial indicator down a plug hole.

I would begin with a piston stop. adjust it to get what looks like about 10-15 degrees off TDC.
turn over the engine unti you feel it touch the stop. mark your flywheel turn it back 245 odd degrees until it touches the other way mark the flywheel there.
Than find the mid point and mark that.
you now have a very accurate TDC marking (becasue its so far from tha axis unlike the cam or crank pulleys)
I have timed all the race cars/engines fromt he flywheel using a TDC marker and a adjustable timing light.


You are also going to want to have a GOOD dial indicator to ensure you have valves in the correct position. i would also be finding out what HKS intended as a valve being "open" do they classify 20 30 40 50 100 thou as a "open valve" these are the minor things that will get you cams set as per spec.

As OC said the best way past getting them spot on the manufactoers spec is to spend alot of time on the dyno to ensure there is not further gains to be made