8 replies to this topic

[ciaran1380]

Year: 1991
Model: Cooper

Engine: 1380, Minispeed Stage 3 head, 286 cam, Twin 1 1/2" hs4 carbs(AAA needles), Ngk BCPR 7es, Aldon yellow dizzy with electronic module. Standard rockers.

I had the Irish Version of the MOT there on saturday. Which failed the car on emissions. They are the same values as the MOT 3.5% CO and 1200PPM HC.

HC reading was a pas the 1st time at 1124PPM but they didnt enter the correct limit on the machine so it failed. 2nd time it failed too but at 3,000PPM. Truth is they couldnt get a stable reading from the exhaust. It was all over the place.
Are there any tricks to eliminate the Overlap on the cam? I suspect this is the main issue with the high HC.

Ive already had the timing and mixture and tappets set as per Minispeeds instructions. Although It wasnt RR. I have the Re-test next week so Im looking for inspiration. Ive heard opening up the gap on the tappets can help?

[ciaran1380]

Anybody have any experience of this?

[taffy1967]

Wouldn't adjusting the mixture help? Can you find a good mobile crypton tuner who'd adjust it as required?

[R1minimagic]

Have you recently rebuilt the engine or resealed the exhaust?

If so, give it a good thrashing for 50 miles or so and then re-test it. There will be a lot of stuff still burning off....

Also, do you have a cat fitted or did you take it off?

[taffy1967]

You don't need a cat on a 1991 Cooper if you have removed it anyway: -

Click Me

Edited by taffy1967, 01 December 2009 - 10:07 PM.

[Sherlock]

If your engine will take it without overheating, you might try retarding the ignition timing by about 2 degrees, I have tried this in the past, more as an experiment than anything else, & there has been a drop in hydrocarbons of 25-50%. Obviously, don't use your engine at high power outputs with that setting.

[ciaran1380]

If your engine will take it without overheating, you might try retarding the ignition timing by about 2 degrees, I have tried this in the past, more as an experiment than anything else, & there has been a drop in hydrocarbons of 25-50%. Obviously, don't use your engine at high power outputs with that setting.

Just what I was looking for, somebody who has done it before. Ill retard the ignition by a few degrees so, I presume anymore than 2 wont have as much effect?, I also opened up the valve clearances quite a bit(35 thousanths) in a attempt to reduce the overlap. I set the mixture spot on well, as well as you can with colourtune. I didnt want to lean it off and cause a misfire, that would be a disaster.

Taffy, Your correct it doesnt need a cat at all, however do you reckon a quick swap for the test would help it pass?

Its in tomorrow so Ill throw it through and see what happens

Thanks for the advice

[ciaran1380]

Thanks for your help. It passed eventually.

HC 1094, CO 0.66%

SO the trick is to open up the valve clearances and spark plug gap

[taffy1967]

Nice one and no you didn't need the cat.

Edited by taffy1967, 04 December 2009 - 12:47 AM.