Could anyone lend me...

[dnb]

A couple of cats that would fit my ACT manifolds?

The Griff got through the fast idle test without cats, but wouldn't quite get through the natural idle test. My guess is that the cam is a little lumpy for this

I'd put an absolute maximum of 5 miles plus an emissions test on them, since I much prefer the car without cats. (since it nearly passes an MOT without them I feel justified in further researching lean burn techniques for reducing MOT emissions and fuel consumption With the cats in, of course, I'd run it at stoichiometric!)

Thanks

[350Matt]

As an aside to this, a mate of mine was trying out a method to get past the emissions test by using an air pump to bleed air into the exhaust and so 'lean out' the tailpipe reading ( the same way most manufacturers do on modern cars). Sorry to say it didn't work as he was a bit circumspect with his plastic pump location and it melted....

But the MOT man said all they have to test is one tailpipe and as long as that tailpipe has gases coming out of it which are below limit then you get a pass.

So a can of calibration gas rigged up to one tailpipe which is otherwise blocked off from the engine and one tailpipe doing all the engine work .....

You see where I'm going with this..

Matt

[dnb]

Maybe I should disconnect every other injector in the firing sequence so half the engine acts as an air pump?

[virgil]

is there no way to adjust the fueling just for the test, then rich it back up after?

[dnb]

The cam is sufficiently wild that it won't idle properly unless the mixture is richer than it would need to pass the test.

During the fast idle test, the cam is beginning to be in its ideal operating range so it all works.

[350Matt]

Not wishing to teach you to suck eggs but have you tried the following:

Reduce the main throttle idle position so the idle control valve has more influence.
Then pump the spark right up, 45-50° isn't uncommon at idle

The idle speed control valve should hopefully keep it under control providing its got enough flow.

This will make it more difficult to drive at low throttle openings as the throttle progression won't be very good but you can put it right post MOT.

On my old Wedge I was running a 280° cam and got the hydrocarbons down to 150ppm with 0.95 Lambda using this method with my Emerald ECU

Matt

[dnb]

The throttle is hard closed so the idle valve is about the only air the engine gets. I got a bit nervous at 35 degrees spark advance at idle, but now I have some evidence, I'll push it further.

Hydrocarbons aren't the problem - I got these down to 85ppm. The problem is that I can't get the natural idle CO below 0.5%

[350Matt]

Hmmm, might be an idea to pop a couple of injector leads off as well say 1 & 6 to try and keep it running smoothly but still leaning out the tailpipe further, best of luck with it.

Let us know if this works

Matt