Adjusting adjustable cam gears.. 130-95?

[Joshstix]

The standard cams are really conservative in an a standard Gen3 torque really crashs after about 5500rpm. I think getting them setup correctly will be a big help if they are as far out as you've measured them to be.

When I built my 3S it wouldn't really idle and made no power down low what so ever, once I got the adjustables and set them up correctly it idled 100 times better and didn't stall constantly. Although the guy I cut off on Windsor road at 8:30 in the morning when I was taking the car for tuning might beg to differ about the stalling, that was a little embarassing.

[chris davey]

Good info.

I actually like the sound of the second method mentioned by turbora28. Don’t really understand the first bit as reading quickly but the second part seems good.

Also, I don’t actually have adjustable cam gears at the moment but I am getting cams very soon. I was going to get adjustable cam gears but the only thing that put me off was someone who had them had lost an engine because the bolts holding them in place had slipped and retarded the cams as far as they could go. This would be a user stuff up right? Just not done up tight enough.

[Joshstix]

I was going to get adjustable cam gears but the only thing that put me off was someone who had them had lost an engine because the bolts holding them in place had slipped and retarded the cams as far as they could go. This would be a user stuff up right? Just not done up tight enough.

If they were something like a HKS set where the bolts screw into aluminium it could well have been that they were done up too tight. This is another reason why I went for the gears I did the 6mm cap screws screw into the original steal gear body.

I used the second method that Joel posted the first time I degreed my cams. I am not a fan of it. We were working in the small hours of the night when doing it and the maths just doesn't work after many hours of furiously working to get the engine together.

Actually I have had a bit of a look around for degreeing instruction and found that those instructions Joel put up were actually written by the guy that made my cam gears. It's a small world.

[Jonny Rochester]

Joel,
The first method you have posted can not really be used. The theory is right, but you can not acurately pin point the crank position when the valve is opened fully. When the valve is opened fully, you can move the crank a few degrees either way and it seams the valve hasn't moved at all.

This is why you have to do it the second way, and record exactly when the valve opens, and when it closes when turning the crank clockwise. You can't blindly add numbers, you really have to think what is happening. But consider your 2 numbers (opening and closing positions) and you will get the valve duration, the time the valve is open for. (This number will be a bit less than the advertised cam duration, due to valve clearance). Divide this number by 2 to help find the lope center.

EG. Intake valve opens at 11deg BTDC, crank spins a full 180deg, and valve closes at 49deg ABDC.

Duration = 11 + 180 + 49 = 240 degrees.
Half of that = 120 degrees.

Lobe center:
120 - 11 = 109 degrees ATDC,

Therefore when valve is fully open, Lobe center is at 109 degrees after top dead center.

BUT, these methods are only for those really keen, with different cams and adjustable cam gears. The 3S-GE standard cam gears are adjustable to some extent. If you have standard cams and cam gears just do this:

Take the cam covers off, and timing belt covers. Get engine to TDC, just roughly using factory markings. (If the crank pully is off, you will see a notch in the small timing belt pulley, that lines up with a mark on the block. If the crank pully is on, line its mark with the plastic belt cover, to 0.) On the camshafts, you will see a cutout on the top of each, just like on a 2T-G or 18R-G. These have to be at the top, and can easily be lined up with the obvious markings, a dot on the cam bearing. Then put the timing belt on, and its all good. There is some adjustment with the stock cam gears, putting the pin in different holes, but just try and get the notches facing up in their position.

This factory position will be close to 110/110 timing. If you want to try more agressive timing, more overlap, the notches on either cam will end up facing each other a bit more.

[Jonny Rochester]

I will add, my method above is a little simple. First you may want to find TDC as others have described. And rather than use the actual valve opening and closing positions, its more acurate to only measure once the valve has moved 0.040" or 0.050" or whatever amount you choose.

[Starfire]

Shaving a head will modify your cam timing as it effectively makes the timing belt a little longer. A thicker than standard head gasket will have the opposite effect.

On a standard engine adjustable cam gears are a luxury item and should be pretty much set to factory timing anyway. On a modified engine they really make life much easier as you can dial in the cams with speed and accuracy. Really good ones like the TODA items have a vernier scale allowing supreme accuracy in the adjustment. Skipping a standard wheel a tooth this way or that against the belt is really quite inaccurate and will produce wildly varied results. On a 4AG 1 tooth of the cam wheel is equal to 20 degrees on the crank.

Always tighten adjustable cam gears with a torque wrench to the manufacturer's specification. You should also use a non hardening thread locker.

[TurboRA28]

Thanks all for this wealth of information its going to come in handy for sure. I think I need to go through and give everyone a rep point

Last night I took the tensioner off and got the notches on the cams lined up as close as I could. I then used the adjustable gears to get them spot on.

I figure thats a good starting point, and hopefully this weekend will get a chance to degree them in using the above mentioned methods.

I've got pretty much free access to a dyno so then i'll chuck it on there and make small changes and some back to back dyno runs and see if I can get it making the power where or close to where i want.

Cheers
Joel

[Billzilla]

I haven't tried bills method but I have a couple of issues with it.

1. Turning the engine backwards then measuring the timing doesn't sit well with me because the timing belt will be getting pulled against the tensioner and not necessarily turn the cams the same amount as the crank
2. The cams are at or very close to maximum lift for quite some time making it extremely difficult to look at the dial guaege and say yep that's maximum lift

Some common sense is also required.
You would always wind the engine back past where the exhaust cam lobe peaks, then forward again to make sure it's in the right place. And you would also measure the lobe lift a little either side of maximum to work out where the real maximum lift is.
But I'll change what I've written on my site to add those, to make it a little easier, thanks.

[limbo]

guys just a note to use reputable adjustable cam gears as if the notches slip they may cause damage to your engine as your intake and exhaust cams will act werid. At high RPM this could be very bad.

I currently have Skunk2 cam gears in my honda. Its only moved +3 degrees intake & -3 degrees exhaust. Just rem that the engines were designed with a neutral max performance across the rev band. If you play with the car in stock form you will loose power at different points in the rev range. The main reason for these cam gears is so that you can tune your power band to your preference.

The only real way to test this is on a dyno.

[roadsailing]

first of all, joel, i hope you are getting good results from your messing with cam timing.

second, i can't let this go, its one of my pet hates.

there IS a difference between slide adjustable pulleys and vernier adjustable pulleys, a fundamental one.



(from left to right) standard cam wheel, vernier adjustable cam wheel, slide adjustable cam wheel.

taken from http://www.billzilla.org/engvalve.htm

Bill, i took this picture from your website because every time i typed in "vernier cam wheel" it just brought up pictures of slide adjustable cam wheels. if you want me to host it elsewhere, i will. if you want me to remove it, i will.

The vernier principle is one that i find interesting, and has many uses, one of which is adjusting your cam timing.

[StuC]

so for ease of setting up then, i take it getting a good set of slide adjustables would be the way to go?

[c2888]

From my hyperrev celica volume 30

ST16x Jap 3sge
5/55 7.2mm
55/5 7.2mm

st16x Jap 3sgte
4/48 7.15mm
48/4 7.15mm

ST18x Jap 3sge
7/57 8.5mm
57/7 8.5mm

st18x jap 3sgte
8/48 8.2mm
56/0 8.2mm

st20x jap 3sge manual
7/65 9.8mm
53/7 8.2mm

st20x jap 3sge auto
7/53 8.7mm
53/7 8.2mm

st20x jap 3sgte
7/53 8.7mm
50/6 8.2mm

st20x jap 3sge vvti
-2~43/78~33 10.5mm
53/11 9.2mm

if there's any errors, blame the book writers, or my crappy translation skills

buy the book, many many nice celicas to perve on.
HYPERREV CELICA VOLUME 30
isbn4-938495-67-8

goodluck with this awesome car

dan

[Billzilla]

lBill, i took this picture from your website because every time i typed in "vernier cam wheel" it just brought up pictures of slide adjustable cam wheels. if you want me to host it elsewhere, i will. if you want me to remove it, i will.

The vernier principle is one that i find interesting, and has many uses, one of which is adjusting your cam timing.

Well, the little markings on the slider-type cam pulleys could also be called 'vernier' as such because they work the same way as the markings on a vernier caliper.
It's just that not many people remember how to read verniers, so they've forgotten about them ...

[oldcorollas]

LOL, i prefer real verniers to "digital calipers" feels nicer to use.. or maybe just more nerdy

[roadsailing]

I did consider that, but joshstix's wheels have one pointer on one half and markings on the other, so they at least aren't vernier anything


the thing i like about vernier calipers is that you can choose what you want the measurement to be, wheras if you have a dial gauge or digital caliper, you have to push it harder to get the "right" reading.

I have a cheap vernier, but i only use it to 0.25 accuracy.