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No more VR4!
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Discussion Starter · #1 ·
I ordered my adjustable cam gears with 3SX's Black Friday sale, and am now getting to installing them. Today I got started and almost have the timing cover off. Car has almost 178k on it, and about 145k I put a new timing belt on. So, roughly 33k on the timing belt. I wasn't planning on changing the timing belt, but here's something interesting.

When I got everything off and the crank and cam timing marks lined up, the intake cam on the forward bank was about 1/2 tooth retarded, with the exhaust cam about 1/3 tooth retarded. The rear bank cams are also retarded, but I didn't catch by how much.

It's been a few years since I did this, so I can't remember if it was this way or not. Once I get the timing cover off I'll know if the belt has stretched by seeing the tensioner. When I installed it I recall for a fact the tensioner didn't expand any when I pulled the pin, it was all snug. If it's expanded, then I'll know the belt stretched.

I see no reason to do a 60k kit since it's only been 33k miles, but if the belt is stretched, I'm thinking I should probably get a new timing belt.

My thought is that I then will need to reset the timing as I put everything back together, and then make my adjustments.

I've been feeling like my car has a bit more turbo lag than it should and less bottom end than it should. This might be my explanation. If the lobe separation angle is smaller and both intake and exhaust cams are retarded (this would be by several degrees), that puts power in the wrong direction for what I want.
 

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No more VR4!
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798 Posts
Discussion Starter · #2 ·
Since nobody had any thoughts, here's what I did. Hopefully it's useful to someone else in the future.

First off, the 3SX cam gears I bought were dead on for their 0 point. So that was a big plus.

With the crank at its 0 point, my cams were all reading around 1/3-1/2 tooth retarded indicated. This makes me figure that, tolerance stack-ups being what they are, the car is probably actually something in the range of -3/-3 from the factory. Since my goal was to improve bottom end and turbo lag, I decided to take this estimation and then did +4/0 on the intake/exhaust cams. This might get me closer to that theoretical actual +1/-3, and at least should improve things.

I then turned the engine over two revolutions with the plugs out to make sure nothing was interfering, and it wasn't.

Obviously the most accurate thing would be to use a degree wheel, but I'm not pulling my engine from the car to do that.

I adjusted the gears before putting them on. While it is theoretically possible to do it on-car, it's much easier off-car.

We'll see how it runs when it gets back together. Worst case, I blow up the engine.
 

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Wheee! 2 wheels is fun!
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8,814 Posts
YES belts stretch. Thats why there is a tensioner.

NO you wont have a "true" degreeing of the cams without a degree wheel. Yes the numbers on the adjustable cogs will allow you to easily vary timing, the results of doing it the right way are always MUCH better.

-SP
 

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There will be Blood!
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A couple of things:

The 3sx gears depending on which version are known to be off on thier markings.

If you used the lower timing cover markings to get your 1/2, and 1/3 tooth retarded numbers the crank position was most likely the cause. The plastic cover is not accurate as a guide mark. The accurate mark is off the gear, and oil pump.

A brand new belt has never aligned 100% perfect on all 5 points. There is always one that is about 1/2 off, and I have done many...

As mentioned without a wheel you really don't knw where you timing is.
 

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No more VR4!
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Discussion Starter · #5 ·
I've put about 100 miles on the car since back together, so I thought I'd give a report.

I ended up doing 4 degrees advanced on the intake cams and 0 on exhaust, because it looked like my cams were all on the retarded side looking strictly at timing marks. Since they were consistently retarded, this made sense and I suspect gets me towards what would be a "true" +1/-3.

The torque on the car has definitely shifted down some. 2,500 RPM used to be where the torque and turbos would kick in. Now, 2,000 is where they kick in. This is exactly what I was hoping to achieve, and makes the car feel much more powerful in street driving. High RPM doesn't seem to be hurt any, and if anything feels stronger, consistent with what the +1/-3 claims to do.

I'm undecided on whether or not I'll experiment more. My feeling is probably not, as there's other stuff I want to do on the car and I'm happy with what I've achieved here. We'll also see what that does to mileage if anything. It's pretty consistent, so it should be easy to tell if there's a change.

In short, I'm very happy with the results. If I ever pull the engine I will absolutely use a degree wheel and time the cams properly.
 
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