c.hydes Posted July 11, 2020 Report Share Posted July 11, 2020 Just a question from my MOT pass yesterday regarding the certificate. (1974 TR6 Injection) Under heading ....................."Non - Catalyst Equipped Vehicle" its says: Limits: Actual Value: Max 4.5% 2.23% PASS Max 1200 ppm 481 ppm PASS Do we know what these gases are, Quote Link to post Share on other sites
c.hydes Posted July 11, 2020 Author Report Share Posted July 11, 2020 1 minute ago, c.hydes said: Just a question from my MOT pass yesterday regarding the certificate. (1974 TR6 Injection) Under heading ....................."Non - Catalyst Equipped Vehicle" its says: Limits: Actual Value: Max 4.5% 2.23% PASS Max 1200 ppm 481 ppm PASS Do we know what these gases are, Also does it tell me anything about the state of my engine ie rich, lean, good, bad etc? Regards, Colin. Quote Link to post Share on other sites
DRD Posted July 11, 2020 Report Share Posted July 11, 2020 (edited) I would assume its 2.23% of CO and 481ppm of Hydrocarbons. A good result, neither too rich or lean at idle. I thought historic cars didn't need an emission test, only no visible smoke. Edited July 11, 2020 by DRD Amend Quote Link to post Share on other sites
RobH Posted July 11, 2020 Report Share Posted July 11, 2020 The numbers are for CO and Hydrocarbons. See table 1 here: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/676700/in-service-exhaust-emission-standards-for-road-vehicles-19th-edition.pdf Quote Link to post Share on other sites
c.hydes Posted July 11, 2020 Author Report Share Posted July 11, 2020 Thanks guys, yes they have never measured the exhaust gases before, but I paid £45 and apparently that includes the cost of an emission test eg a modern car, so asked the engineer to give me a print out for interest. He did say they were much higher when started, but soon came down to these values above. If the results indicate a generally healthy car (at idle) then that's good. Guess it may not be so healthy at higher rpm`s though.? Cheers, Colin. Quote Link to post Share on other sites
c.hydes Posted July 11, 2020 Author Report Share Posted July 11, 2020 Just looked at some past postings on this topic that seem to indicate 2.23% CO at idle is a bit lean and going to say 4% could stop the dreaded "pinking" which I seem to have. So as a experiment how do I increase it a bit, metering unit tweek, advance/retard timing form 8°BTDC etc Colin. Quote Link to post Share on other sites
kcsun Posted July 11, 2020 Report Share Posted July 11, 2020 (edited) Agree it is a bit lean. My car car failed its French MOT the other day with 8.5%!! (but it ran really well) My "Man who does" got it down by adjusting the advance/retard on the distributor and the air - screw on the manifold. Went back for retest and it was still 5.9%, very friendly helpful French MOT man then waited for 40 minutes while minor adjustments made till eventually a reading of 3.5% and a karate kick to the machine to save the data got the result we needed (it is also "under 4.5%" in France) I think that now I have my new MOT valid for5 years it may need tweaking up a little. kc (PS we decided not to fiddle with the MU) Edited July 11, 2020 by kcsun added the PS Quote Link to post Share on other sites
TR6_PI_1969 Posted July 11, 2020 Report Share Posted July 11, 2020 Hi, I was reading your topic, are you sure that the MOT gives you the 'raw' CO value? ... Because there's also sth called the corrected CO value, CO C on the picture attached, which takes into account the CO2 value. The formula should be : CO C = CO * (15/(CO+CO2)). If you make the calculation with my values, you will indeed find 4.82 for CO C. The picture is from my PI car, but a long time ago. From what I understand, it takes into account the possible air dilution in the exhaust line (e.g. a hole in the line). Thanks for your feedback ! Quote Link to post Share on other sites
TR6_PI_1969 Posted July 11, 2020 Report Share Posted July 11, 2020 Better with the picture! Quote Link to post Share on other sites
elclem1 Posted July 12, 2020 Report Share Posted July 12, 2020 You are indeed correct an air leak into the exhaust will upset the reading quite dramatically. However a good mot man will know this, Quote Link to post Share on other sites
DaveR Posted July 12, 2020 Report Share Posted July 12, 2020 I echo the comments re the CO being too lean, that's even for the 125BHP engines. Dave Quote Link to post Share on other sites
DRD Posted July 12, 2020 Report Share Posted July 12, 2020 12 hours ago, c.hydes said: Just looked at some past postings on this topic that seem to indicate 2.23% CO at idle is a bit lean and going to say 4% could stop the dreaded "pinking" which I seem to have. So as a experiment how do I increase it a bit, metering unit tweek, advance/retard timing form 8°BTDC etc Colin. If its pinking then maybe the timing needs retarding a bit. What petrol are you using? But PI does need to run slightly richer to compensate for transient leaning of the mixture when the throttle opens quickly. Not sure what that translates to at idle though. If you do a search here surely something from one of the gurus on here will come up. Quote Link to post Share on other sites
HSM Posted July 12, 2020 Report Share Posted July 12, 2020 From my old Autodata manual %co at an idle of 750-800rpm is 2.5 to 3.5, as a comparison the TR7 is 2.0-4.5. Harvey S. Maitland Quote Link to post Share on other sites
c.hydes Posted July 12, 2020 Author Report Share Posted July 12, 2020 Thanks for the input. To answer some of your questions: The MOT printout results do not give any other explanations other than what I highlighted in my first post. I have retarded the timing from 11°BTDC to 8° and my advance is approx. 26 - 28 max at the crankshaft. I use standard supermarket petrol 95 RON, and have a fast road camshaft with a stage 2 conversion, as was a US 125 bhp but converted to 150 with higher compression . Tappets are 14 and 18 thou, vacuum at idle is 9/10" Hg, all BP6ES plugs are light brown, but still get pinking or what I believe is pinking. My thoughts are: Try 99 RON? Retard ignition further? Tweek the MU to add a bit more richness? Cheers, Colin. Quote Link to post Share on other sites
DRD Posted July 12, 2020 Report Share Posted July 12, 2020 Sounds like it retarded enough, you could try Shell V Power and see if that helps. Your engine is a similar spec to mine and because its non standard I got it setup on a rolling road. Tbh the CO at idle is fairly meaningless in that case. Mine runs OK at 11 BTDC but I do user super unleaded and an octane booster. Also I've found cooler iridium plugs better as well. They cured my running on problem. Quote Link to post Share on other sites
Kiwifrog Posted July 12, 2020 Report Share Posted July 12, 2020 (edited) 14 hours ago, TR6_PI_1969 said: Better with the picture! Normally in France you are only obliged to pass a pollution test in a petrol car if it was registered after the first of octobe 1972 Peu importe le carburant consommé, le contrôle anti-pollution concerne : Les voitures à essence mises en circulation à partir du 01/10/1972, Les véhicules diesel mis en circulation à partir du 01/01/80. cheers Alan Edited July 12, 2020 by Kiwifrog Quote Link to post Share on other sites
TR6_PI_1969 Posted July 12, 2020 Report Share Posted July 12, 2020 4 hours ago, Kiwifrog said: Normally in France you are only obliged to pass a pollution test in a petrol car if it was registered after the first of octobe 1972 Peu importe le carburant consommé, le contrôle anti-pollution concerne : Les voitures à essence mises en circulation à partir du 01/10/1972, Les véhicules diesel mis en circulation à partir du 01/01/80. cheers Alan Correct. My car being a 69 model year, it doesn't need the pollution test. I asked for the test on purpose, separately from MOT. It'seems on a voluntary base, I was curious. Quote Link to post Share on other sites
TR6_PI_1969 Posted July 12, 2020 Report Share Posted July 12, 2020 It was on a voluntary base, sorry, for mistake, no It'seems Quote Link to post Share on other sites
kcsun Posted July 12, 2020 Report Share Posted July 12, 2020 Damm mine is a 73 kc Quote Link to post Share on other sites
Spit_2.5PI Posted July 12, 2020 Report Share Posted July 12, 2020 9 hours ago, c.hydes said: I use standard supermarket petrol 95 RON, and have a fast road camshaft with a stage 2 conversion, as was a US 125 bhp but converted to 150 with higher compression . Tappets are 14 and 18 thou, vacuum at idle is 9/10" Hg, all BP6ES plugs are light brown, but still get pinking or what I believe is pinking. Colin, definitely change to using super unleaded which will be at least 97-octane. Some super unleaded are even higher, such as Shell VPower (99) as DRD suggests. Personally I use Esso which doesn't have the dreaded ethanol in it round our way. Cheers, Richard Quote Link to post Share on other sites
c.hydes Posted July 25, 2020 Author Report Share Posted July 25, 2020 Thanks everyone for your comments. Think I will try some of that "99 cocktail" petrol now, If it still pinks the your other suggestions will follow. Regards Colin. Quote Link to post Share on other sites
JochemsTR Posted July 26, 2020 Report Share Posted July 26, 2020 On 7/12/2020 at 11:58 AM, c.hydes said: Thanks for the input. To answer some of your questions: The MOT printout results do not give any other explanations other than what I highlighted in my first post. I have retarded the timing from 11°BTDC to 8° and my advance is approx. 26 - 28 max at the crankshaft. I use standard supermarket petrol 95 RON, and have a fast road camshaft with a stage 2 conversion, as was a US 125 bhp but converted to 150 with higher compression . Tappets are 14 and 18 thou, vacuum at idle is 9/10" Hg, all BP6ES plugs are light brown, but still get pinking or what I believe is pinking. My thoughts are: Try 99 RON? Retard ignition further? Tweek the MU to add a bit more richness? Cheers, Colin. Emission consists out of following measurements CO HC CO2 O2 Lambda (calculated from above values) 1. CO and Lambda are NOT directly relatable. You can have a 3.30 CO with 1.077 Lamda. Do not go by any of the CO vs Lambda tables found on the internet. Lambda takes into consideration all values. Most "cheap" home testers only provide you with CO value. 2.Retarding ignition helps with HC and CO values (mostly high in combination with long duration cam). But only with electronic ignition since it pulls bad from low end. We did some tests playing with this. normally 9-10° advance, going to -2°. Modern cars go upto -10°. 3. Tweeking MU based only on CO value is not good. You need all values. Go to a garage, they have those nice Bosch Testers....pay them few € and get your results. Jochem Quote Link to post Share on other sites
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