240 General: New (to me) 1980 Volvo 244

[Othen]

The Barge and I had to go and see a man about a dog this morn, and we have just returned with a shiny new 13 month MoT certificate (with no advisories).

It wasn't quite plain sailing as we had to have two goes at the CO emissions. The first test was this morn, the Barge passed everything except the emissions test - but the garage agreed on a re-test at 5:30 this eve: where it just snuck in under 4.5% CO (3.74%). That is still higher than I'd like, but I've run out of adjustment on the Stromberg CD 175 CO screw - and the green book figure is 2.5%. I think what I'll have to do is drop the needle down one notch, then adjust the screw up again. The MoT garage has kindly agreed to let me use its CO tester for some fine tuning one day next week. I might as well take the opportunity to change the diaphragm at the same time.

I'm really happy that the last few months work on the Barge has paid off and it has a new test with no advisories - in fact I'm quite proud of that. This will be the Barge's last compulsory MoT (it will turn 40 on 1 June next year).

All in all it was worth going to see that man about a dog

[Moomoo]

Excellent bud!👍😁

[Laird Scooby]

Congrats on the pass Alan!

Before you go dismembering the Stromberg (Not Pierbug? ), have you given the PCV system a thorough clean since you got the Barge? If not, give it a thorough clean and watch those emissions drop and your economy is likely to go up as well.
Also if you have one of those horrible constant temperature air intakes on the carb, disconnect the corrugated aluminium hose between the exhaust manifold and the air thermovalve. It may or may not drop the CO reading to a more sensible level.

Also verify the ignition timing is as advanced as it needs to be at idle, don't forget to disconnect and plug the vacuum tube from the capsule on the dizzy before checking/adjusting or it can end up retarded compared to where it should be.

Hopefully one or other of those suggestions has it running as it should be once more!

[Othen]

Originally Posted by Moomoo

Excellent bud!👍😁

I’m feeling smugly proud of myself (and the Barge) Andrew. I couldn’t really have known about the high CO without a meter, and everything else was spot on.

The Stromberg carburettor is really simple, so that shouldn’t hinder me much.

[Moomoo]

Originally Posted by Othen

I’m feeling smugly proud of myself (and the Barge) Andrew. I couldn’t really have known about the high CO without a meter, and everything else was spot on.

The Stromberg carburettor is really simple, so that shouldn’t hinder me much.

Just checked Baby’s CO2 on last month’s MOT, permitted , 3.5%, actual, 0.4%.
Not the same equipment, I know, just saying.

I’ve always been a carb man, not that I’ve ever had trouble with fuel injection, it’s an age thing!👍🤔

[Othen]

Originally Posted by Moomoo

Just checked Baby’s CO2 on last month’s MOT, permitted , 3.5%, actual, 0.4%.
Not the same equipment, I know, just saying.

I’ve always been a carb man, not that I’ve ever had trouble with fuel injection, it’s an age thing!👍🤔

2.5% is a good aim for a carburettor engine Andrew.

[Moomoo]

Originally Posted by Othen

2.5% is a good aim for a carburettor engine Andrew.

Oh aye, not bad at all!👍

[Othen]

Originally Posted by Laird Scooby

Congrats on the pass Alan!

Before you go dismembering the Stromberg (Not Pierbug? ), have you given the PCV system a thorough clean since you got the Barge? If not, give it a thorough clean and watch those emissions drop and your economy is likely to go up as well.
Also if you have one of those horrible constant temperature air intakes on the carb, disconnect the corrugated aluminium hose between the exhaust manifold and the air thermovalve. It may or may not drop the CO reading to a more sensible level.

Also verify the ignition timing is as advanced as it needs to be at idle, don't forget to disconnect and plug the vacuum tube from the capsule on the dizzy before checking/adjusting or it can end up retarded compared to where it should be.

Hopefully one or other of those suggestions has it running as it should be once more!

Certainly Stromberg:



It appears to be almost identical to the Pierberg CDUS 175 I had on the RB though - a very simple instrument.



If I remember correctly Dave, you advocated having an air warming device when I was going to get rid of it :-). No matter, reinstating the plumbing to the exhaust was worth it just for the aesthetic. I am suspicious about the constant air device working properly though, so my investigations will begin there. I have a spare device (complete air box), but unless I can prove to myself it is all working properly I may disable the flap inside the box completely so it only takes fresh air from behind the grille. The bendy pipe and exhaust plate could remain in place just so it looks original. The system is probably quite useful at -30c in Northern Sweden, but there isn't much of a requirement in balmy Costa del Corby.

Watch this space :-)

PS. For my reference:

Originally Posted by Bugjam1999

Hi,

Couple of things- ditch the hot air source bracket off the downpipe and the associated tube, then remove the airbox and check the thermostatic flap hasn’t seized in the position for warm air- the concept of that warm air tube is to supply above freezing air in far below-zero conditions, which you aren’t going to find in the U.K. Remove the thermostatic actuator and flap, use an aerosol/spray paint lid to block that entry to the airbox and replace.

Those crimp connectors to add the extra gauges are how Volvo recommended the connections were made, I’ve got a copy of the original dealer fitting instructions I can email to you if you wish.

Cheers

[Othen]

Following on from the past above - I'm looking for the culprit that has led to high CO emissions. First I checked the choke mechanism, which was all just fine. I was slightly suspicious that the constant air temperature device that I had reinstated a few months ago might be at fault - because perhaps a previous owner had removed the exhaust plate because it wasn't functioning properly?

Having taken the air box off for a better look, and tested the device with a hot air gun I could see that it was moving when heated, but seemed to need quite a lot of heat to make it open fully. I had not convinced myself that it was operating properly (a bit like the light in the fridge), so I decided to disable it:



... I drilled two small holes and have zip-tied the flap in the open position (so it will only ever receive cold air from behind the grille).

I'll test it out over the next few days to see if I think this has led to an improvement. If this was the cause of excessive CO emissions the motor should now be running too lean because I turned the adjustment screw down for the MoT re-test yesterday.

... watch this space.

[Laird Scooby]

Best way to see if it is now too lean is to put it on the CO meter. Also have you checked the PCV system? Unless you've cleaned it in the past 2 months, it's worth checking just to ensure all the various parts are clean and clear.