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Member
Posts: 67
| Just had my 1.1 HIF38 - carbed Metro in for MOT and the CO level is at 10.01%! Max is 3.5% and the HC is at 533ppm - seems high too - any ideas please? I don't have my own exhaust gas analyzer or a colortune. Some bush-mechanicing advice would be welcome. |
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Expert
Posts: 4458
 
Location: Jelling, Denmark | Either turn the adjuster screw out a full revolution and bring a suitable screw driver with you to the next mot to do the final adjustment or go to a garage and have it adjusted, it shouldnt take more than 5 minutes to adjust. There isnt and easy way to do it without measuring. |
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Member
Posts: 67
| DotMatrix - 31/12/2016 8:18 PM
Either turn the adjuster screw out a full revolution and bring a suitable screw driver with you to the next mot to do the final adjustment or go to a garage and have it adjusted, it shouldnt take more than 5 minutes to adjust. There isnt and easy way to do it without measuring.
Thanks for that. Have you any idea roughly how much reduction in CO a turn out is worth? My engine is producing 6.5% too much and that's a lot. Also, what about that diaphragm valve inside the housing at the side that is rumoured to leak? Any mileage in that causing an issue do you think? Finally, if I were to set the jet level with the bridge, is there a standard number of turns in with the screw to set the mixture about right? Thanks in advance. |
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Expert
Posts: 4458
Location: Jelling, Denmark | Re-Carbed - 1/1/2017 10:55 PM
DotMatrix - 31/12/2016 8:18 PM
Either turn the adjuster screw out a full revolution and bring a suitable screw driver with you to the next mot to do the final adjustment or go to a garage and have it adjusted, it shouldnt take more than 5 minutes to adjust. There isnt and easy way to do it without measuring.
Thanks for that. Have you any idea roughly how much reduction in CO a turn out is worth? My engine is producing 6.5% too much and that's a lot. Also, what about that diaphragm valve inside the housing at the side that is rumoured to leak? Any mileage in that causing an issue do you think? Finally, if I were to set the jet level with the bridge, is there a standard number of turns in with the screw to set the mixture about right? Thanks in advance.
my guess (emphasis on guess) would be 1-2% reduction for one turn. The reason I write you can turn it out is "as a show of good faith" when you turn up at your local MOT place again with a screwdriver.
but the only real way to adjust this is to measure the co level while turning the screw. it must be very cheap to get at garage to do this adjustment as it shouldn't take more than 5 minutes.
I don't know about the possible leaking diaphragm. |
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Member
Posts: 67
| DotMatrix - 2/1/2017 12:39 AM
Re-Carbed - 1/1/2017 10:55 PM
DotMatrix - 31/12/2016 8:18 PM
Either turn the adjuster screw out a full revolution and bring a suitable screw driver with you to the next mot to do the final adjustment or go to a garage and have it adjusted, it shouldnt take more than 5 minutes to adjust. There isnt and easy way to do it without measuring.
Thanks for that. Have you any idea roughly how much reduction in CO a turn out is worth? My engine is producing 6.5% too much and that's a lot. Also, what about that diaphragm valve inside the housing at the side that is rumoured to leak? Any mileage in that causing an issue do you think? Finally, if I were to set the jet level with the bridge, is there a standard number of turns in with the screw to set the mixture about right? Thanks in advance.
my guess (emphasis on guess ) would be 1-2% reduction for one turn. The reason I write you can turn it out is "as a show of good faith" when you turn up at your local MOT place again with a screwdriver.
but the only real way to adjust this is to measure the co level while turning the screw. it must be very cheap to get at garage to do this adjustment as it shouldn't take more than 5 minutes.
I don't know about the possible leaking diaphragm.
Thanks again, and happy new year. |
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Member
Posts: 67
| Re-Carbed - 2/1/2017 3:38 PM
DotMatrix - 2/1/2017 12:39 AM
Re-Carbed - 1/1/2017 10:55 PM
DotMatrix - 31/12/2016 8:18 PM
Either turn the adjuster screw out a full revolution and bring a suitable screw driver with you to the next mot to do the final adjustment or go to a garage and have it adjusted, it shouldnt take more than 5 minutes to adjust. There isnt and easy way to do it without measuring.
Thanks for that. Have you any idea roughly how much reduction in CO a turn out is worth? My engine is producing 6.5% too much and that's a lot. Also, what about that diaphragm valve inside the housing at the side that is rumoured to leak? Any mileage in that causing an issue do you think? Finally, if I were to set the jet level with the bridge, is there a standard number of turns in with the screw to set the mixture about right? Thanks in advance.
my guess (emphasis on guess ) would be 1-2% reduction for one turn. The reason I write you can turn it out is "as a show of good faith" when you turn up at your local MOT place again with a screwdriver.
but the only real way to adjust this is to measure the co level while turning the screw. it must be very cheap to get at garage to do this adjustment as it shouldn't take more than 5 minutes.
I don't know about the possible leaking diaphragm.
Thanks again, and happy new year.
Update - Following online advice I removed the vacuum chamber and piston and adjusted the jet upward as far I could with the mixture screw which was pretty much level with the bridge. I then wound the mixture screw in 1.5 turns. Why 1.5? well - the weather was cold and the HIF38 has a bimetallic strip to compensate for fuel viscocity in the bowl. The strip raises the jet as the fuel becomes thinner due to warming up. The initial mixture screw setting should be 2.0 turns for a warm engine so I've tried to compensate for this by enriching 1/2 turn less. I reassembled the carb and the engine seemed to sound better when started - less fumy and a better "note". Tomorrow I'll give it a good ragging around and see what it's like - should be good. I once owned a 1100cc MG Midget MK2 and my Metro handles similarly - good fun. |
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High CO
