CO% emissions.

[macdonald.dm]

Hello.

My Berli just failed its first MOT in my 3 year ownership...

A teeny bit of play in a lower ball joint - fair enough - but it also failed on CO emissions by 0.07%!

Ok, this should be easy to tweak out, but looking back over my previous MOT results, I find that the max permitted CO limit for my car on it's last MOT was 4.5%, but on this occasion the max limit was stated as being only 3.5%. I notice they also dated my car this time as being 1977, whereas it was actually first registered in '75.

I've tried a Google, but get far too many returns! So, does anyone know what the correct max CO% limit is for cars of 1975 vintage?

Can you also confirm that the 'volume control screw' on the Weber (32/36) carb adjusts the AIR going through it, so turning it ANTIclockwise will weaken the idle mixture, and so presumably reduce the CO output?

Many thanks.

(PS. Who does the immaculate dark-blue, H-reg'd Cabrio I came across in Barnstaple belong to? I noticed a MOC 2008 sticker on it, so I presume a current member! BEAUTIFUL...)

[Dane_Rescueman]

Re: CO% emissions.

Donnie,
If you can confirm the age of your engine block as 1975, the only MoT test is a visual smoke test for this age. Burton Power have a table in their catalogue with which you can decipher the Ford engine number to give month and year of manufacture for your MoT chap. If you do not have the catalogue, post your engine number and I will get it for you. I think he is being overzealous! I actually used to ask my MoT man to give it a CO test (although he said it did not need one). My own CO meter is very temperamental and so I used the test as confirmation that all was OK .My last engine (Same carb as yours) gave around 1.6% three years running. This is probably a bit lean for that particular engine though. It was a 1976 lump. You will be able to match this if your engine is standard.
I have just installed a Vulcan injected pinto which is dated 1988 and so I just avoid the most stringent emissions test but have to pass the next one down (My engine, having covered 7 miles, was OK at 0.85%CO). It passed OK a month ago.

Make friends with your MoT man and take a screwdriver with you. He may well allow an in situ adjustment!

[gaddbrose]

Re: CO% emissions.

Hi Donnie. reference your emmission check. You don't need one!!! It seems that kit cars enjoy certain priviledges, one , is exemtion from the emmissions test. My Berli has had its MOT this afternoon, and the examiner volunteered the info. as it saved him the work.[I was going to mention it anyway,]. If I was you , I'd challenge that decision, but nicely. Brian.

[macdonald.dm]

Re: CO% emissions.

Dane and Brian - many thanks.

Obviously, I intend to tweak my carb as much as possible as it's good to having it running at its optimum setting, although I understand the only mixture adjustment the carb has - the volume control screw - only affects it at idle? Out of interest, do you know if it also has an effect at higher revs too?

It's always nice to know that it's likely he got the figure wrong, tho'! Looking back at old MOTs, the car usually had just over 2% emissions, which was well inside the - then - stated max of 4.5%. For this max figure to have suddenly fallen by a whole %, putting my poor Berli fractionally outside it, was a tad annoying. Mind you, it did also fail on the ball joint...

I'm not complaining really - it was a new guy, and he was VERY thorough!

Thanks again, gents - brilliant as always.

[macdonald.dm]

Re: CO% emissions.

Jeepers, just tried another Google this time using 'MOT' instead of 'VOSA'. The answer I wanted came up right away (I thought it wasn't 'meant' to be called 'MOT'?!)

Confirms what you were saying, gents - up to 1/8/1975, it's a visual test only, and between then and '86 it's 4.5% max. Either way, I've been diddled!

No problem. Now to sort my balls...

[gouldsborough7]

Re: CO% emissions.

Hi Donnie
I had my Berli (1981 Cortina Pinto) MOT'd this morning, and like my earlier Robin Hood (with 1987 Pinto) there was no requirement to have its CO measured.

Regarding the carb mixture, there are 2 screws on my carb, the obvious one and another facing the rocker cover. Admittedly mine has a 3 litre Granada carb, but I suspect the design is similar - just the throttle flaps open together when you press the gas pedal!

To adjust the inner screw is a pain to reach and requires a screwdriver (or home-made equivalent) bent at 90 degrees. When I first started tweaking the mixuture, and only adjusting the outer screw, somebody flagged up the hidden inner screw, which I found was screwed in quite tight. I re-started with both screws in about the same position, e.g. one and a half to two turns from the fully screwed-in position. Because of the access problem adjacent to the rock cover, the final adjustment was done only on the outer screw, to get the tickover and pick-up response to be fairly smooth.
An early mod was to junk the auto-choke, which made starting a real pain. I have ended up with 2 choke knobs, one dealing with the choke flap only, and the other just the revs. Gives a lot more control on a cold engine.
Cheers
Mike

[macdonald.dm]

Re: CO% emissions.

Cheers Mike.

I'm surprised your '81 Pinto wasn't tested to be below 4.5% as the .gov site informed me. And your old R Hood should have been checked to 3.5% according to my 'research'!

Thanks for the info on the carb. I think mine has only a single mixture screw which is, indeed, on the side next to the rocker cover. However, it is drilled in at and angle, so getting a screwdriver onto it wasn't too hard. I've backed it out around a turn without any complaint from the engine, and also slightly reduced my tick-over rate.

Do you know if the mixture (volume control screw) has an effect at higher revs, or just at idle?

Yeah, I ditched my auto-choke too - what a pain that thing was! I did a DIY job on it for no cost other than a choke cable! It works by rotating the auto-choke housing - it was shown as an article in Pitstop. It's remarkable just how little choke the Weber needs, even in cold weather - the auto choke must have been a real waste.

Cheers.

[gouldsborough7]

Re: CO% emissions.

Hi Donnie
I believe the mixture screw(s) only affects the lower revs and small throttle openings. Once you have your foot hard down on the 'go' pedal, the other jets take over. However, as mine is over-carburetted with the Grannie carb, the pedal does not have to be pressed very much to get some action! So I believe the mixture screw positions in my case are fairly critical.

After I made a number of adjustments, there was a noticable improvement in engine behaviour when pressing and releasing the accelerator. Previously, it was accompanied by a fair amount of transmission jerking, as well as a lack of instant response. The response is now good (!), but I haven't got rid of the transmission jerking entirely. Probably a sympton of being over-carbed, perhaps wear in the throttle spindles allowing extra air to be sucked in, as well as worn UJ's. One could spend a lot of dosh to sort these things out, and get only a minor improvement in return.

Regarding the latter, my local garage proprietor is very kit-car keen, and he says the Berli misalignment of axle/gearbox/engine layout is causing the propshaft UJ's to work extra hard. The tight space in the propshaft tunnel does not allow for any realignment.

Cheers
Mike

[GaryW]

Re: CO% emissions.

Hi Donnie,
With regards to the mixture screw on a 32/26 weber. There is a procedure for setting "lean best idle". I did this on mine and it was pretty accurate. However, to re-enforce previous posts once running it's the primary and secondary jets that will determine the amount of fuel going through.
This link contains the instructions for setting lean best idle - hope it helps http://www.redlineweber.com/html/Tech/carburetor_set_up_and_lean_best_.htm
Good luck!

[GaryW]

Re: CO% emissions.

Whoops, cocked up the link. Should be
http://www.redlineweber.com/html/Tech/carburetor_set_up_and_lean_best_.htm

[macdonald.dm]

Re: CO% emissions.

Thanks Gary - that's perfect!

Mike, are you saying your particular car is poorly aligned in the engine/box/axle setup, or is it a 'standard' Berli quirk?

[macdonald.dm]

Re: CO% emissions.

Gary, can you confirm that the mixture (or 'volume control screw') controls 'air' rather than 'fuel'? So that turning it IN (clockwise) reduces air and enriches the mixture, and vice versa?

Thanks.

[gaddbrose]

Re: CO% emissions.

Hi Guys, you have mentioned the possible misalignment of the axle and gearbox in the Berli, leading to vibrations etc. Do you realise that Ford's deliberately misaligned the prop shaft by making one side of the rear axle longer than the other. I think one side, the off side, is about 2" shorter than the nearside,and from above, the shaft appeared out of line. This was done to ensure that the Hardy Spicer couplings in the prop shaft had to move as the shaft rotated, and therefore the needle bearings ran on a varying track as it turned. If the propshaft ran centrally, then the bearings would not move angularly and run in the same track, and eventually cause a problem known as "brinelling", and the next step would be an early failure. Believe me, in the early days when members started to build their cars in great numbers, the Marlins would regularly get calls from frustrated builders complaining about the offset. On the Seirra based version, once again the prop shafts are of different lengths for the same reason. Thought you might like to know that.!!!! regards Brian.

[gouldsborough7]

Re: CO% emissions.

Hi Brian
That's very interesting about the misalignment and brinelling etc. When my garage man pointed out the misalignment, I was already seeking his advice and help with car up 6 feet in the air on a hydraulic hoist, to identify why the propshaft & gearbox were bashing the transmission tunnel. When one can stand under the car and see just how little space there is for everything to fit in, including handbrake mechanism, trying to rectify any 'misalignment' caused by Ford is a No Go area. Having replaced the engine and gearbox mountings, and experimented with spacers in various places, I decided that the occasional knock going over a pothole was a small price to pay. The UJ's would just have to suffer, or so I thought, but from what you say the misalignment is as designed.
Cheers
Mike

[macdonald.dm]

Re: CO% emissions.

Well, car flew through re-test this morning.

I had tweaked the carb by weakening the mix (volume control screw) until the point is was beginning to run a bit rough, and then backing it in a teeny bit. This was based on me assuming that this screw controlled AIR, as I was pretty sure, from the way the tiny bore opens to the manifold, that it couldn't possibly be controlling a neat flow of fuel...

Well, bugger me with a bargepole, no wonder my car failed its emissions, 'cos I'd adjusted this screw many months ago on this very - WRONG - premiss.

This was the one bit of info that I always wanted to know, but was simply never explained on any website on the Weber - until one last search late last night revealed that this screw controls the volume of a MIX of fuel and air, so turning it out ENRICHES the supply at idle/low speed.

So, just before heading off for the MOT, I adjusted the screw clockwise instead, until revs almost falling off. Result? CO of 1.07%. (Ok, this is now probably a tad weak - I could hear the exhaust lightly 'popping' on over-run! - so I've enriched it slightly since.)

So, I'd gotten it wrong for almost a year, running on an unnecessarily rich mix. Rats!


Info re. CO level emissions at MOT (From 'The MOT Inspection Manual', 2004):

(a) Petrol cars first used before 1st Aug 1975 - visual only.
(b) First used between Aug '75 and 31st July 1986 - < 4.5%
(c) Aug '86 - 31st July '92 - < 3.5%

HOWEVER, "For emissions purposes only, kit cars and amateur built vehicles first used before 1st Aug 1998 are to be considered first used before 1st Aug 1975."

So, visual only pre-1998!