Ferrari 412 - Failed Inspection. High HC and CO Values

The soot is due to the over rich condition that "covered up" the timing issue. (too much advance).

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Yes, I am referring to camshaft timing, given how the car immediately starts and accelerates, I am ruling out ignition timing.

I have remove everything again and retarded the camshaft timing a few degrees.

Cold start injectors are disconnected and checked for leaks, not needed in 35+ degree weather

Air bypass is also fully closed.

 

Raemin mentiekd the air bypass valve, not scew - that must be closed after warm up.

Air bypass srews should be fully closed and only used if the 2 banks cannot be balanced using the throttle plate adjustment screws.

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i have re-set the valve timing now and will attempt re-start tomorrow.

I will do a compression test later today - I was getting over 160 PSI with timing advanced, I assume this will come down some.

Will share the before/after pictures of the initial assembly marks on as to see the differences.

 

Here are the timing marks now:

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No, I replaced them with German made ones. But I believe my actual problem was never the K-Jet, but rather the overly advanced timing, which "forced" me to run it much richer for it to run well.

As long as the K-Jet puts out fuel and it is sufficiently atomized and in a reasonable quantity, it will run. Even the Bosch manual does not call for a "perfect' spray pattern.



I have seen old V8 Mercedes with extremely bad injectors and were running well.

Most of the fuel being injected (see #7) turns into gaseous state as it is sucked into the intake port; remember it goes through the port, then hits the stem and the head (underhead) of the valve, all this at an extremely high speed and heat.

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If I were to do it again, which I will at some point, I will use a dial indicator instead of the "break free" valve shim method.

I think at this point we can get from the engine in running condition to "setting the valve timing" (pins removed) in under 2 hours.

Using an electrical screwdriver makes a huge difference, as there are over 100 nuts what have to be removed - this alone can take up to 30 mins.

Another "tip" for removing the metering head; just pull out the injectors, and the remove it with the injector lines (all you need to do is remove the 2 large fuel delivery and return lines and the cold start injector hose). Keep the WUR connections attached and remove together with everything else.

The most uncomfortable part to remove are thr distributor caps - this will take around 10 mins each. Using a small ratchet makes a difference (3 x 8mm bolts)

NOTE: The A/C compressor is not installed.

 

WRONG - the Bosch/Ferrari manual very clearly states that the air by-pass screw should be normally closed.

 

Interesting, I only have the 400i WSM to go by.

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UPATE: Engine started, smell is gone and runs very smooth, BUT has no power at all in the lower rpm band.

Seems it was retarded too much.

Incredible what an effect a seemingly small adjustment can make.

I will take the car for the inspection and then reset the timing again.

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Had some "adjustment" shims made out of stainless steel, see picture below.

Of the 4 shims, the sizes I needed to get to the 0.5mm clearance were 3.53, 3.5 or 3.55mm. My shims were 3.6, 3.75... These are all very small differences, that result in many degrees timing differences.

Once I have my dial indicator, I will be able to exactly know how many degrees correspond to x amount of valve moment.

All of this was done without a dail indicator, only using the "break free" method.

Timing has been reset now as close as possible and will start tomorrow.

Will send it for inspection again next week, will be interesting to see what CO and HC values I get.

At some point I will do it again using a dail indicator where I can exactly determine the moment the valve begins to be moved by the cam lobe and can add/subtract the clearance to get the exact 0.50mm.

Using an electric screwdriver has greatly reduce the time needed to disaamble everything.

One observation, you need to have new steel lock tabs (4) for the camshaft sprocket bolts, as these cannot be reused. I had them fabricated in hardened steel by the machine shop. Image Unavailable, Please Login

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Small update: I passed the inspection, the values are now nearly 20x less!

CO is a 0.49% and HC at 265 PPM, slightly above what is stated in the owners' manual - I am sure a good "Italian tune up" would clean out the exhaust from the previous running condition.

The issue is that the car has very little low end torque, for some reason I have too much retard in the intake valve.

Conclusion:

1. My issue was ALL and ONLY due to camshaft timing - as I had timed it only using the initial assembly marks.

2. The intake valves were previously covered in soot, and this has now stopped (I looked with an endoscope). This was due to the very advanced intake valve opening, meaning, some of the exhaust was being "pushed out" of the intake (as the intake open starts happens while the piston is still traveling upwards during the exhaust stroke). This is no longer the case. Specs call for 16 degrees B.T.D.C.

3. Valve overlap is everything is greatly affects emissions and performance.

4. Very slight differences on with the cam timing make a huge difference.

Again, thanks to all - my saga continues.