16 replies to this topic

[gutted]

Drive it there early one morning, leave it to cool down for 4 hours or so, do some shopping or whatever and get him to look at it after lunch!l. Especially in winter, it will obviously cool down quick!
 

 

 

 

There's a ridiculously strong smell of fuel out the exhaust (even with no choke). I even get actual black smoke out the back.

This smell of fuel and black smoke indicates something is wrong with the carb or its setup and it is running too rich as if permanently on choke. This would also result in poor fuel consumption (mpg) and cold running of the engine plus in the longer term piston/bore wear due to oil being washed off the surface of the cylinder bores. Might be worth you overhauling the HIF SU carb or swapping it for a known good replacement with the correct needle, etc.Have you also checked the choke is shutting off fully? At over a 100k miles the carb will likely be in need of an overhaul, clean and a check over for general wear.

Ideally when the cold weather and poor cold running symptoms return you need to take it to the Rolling Road you went to previously and get them to diagnose and pinpoint the problem while it is actually happening.
Back in the day you could have gone to a local breakers and picked up another HIF SU carb off a similar Metro for a reasonable price and then swapped over as a test. Not sure what the going rate on ebay is these days for a good or refurbished HIF44 SU but might be worth a try to eliminate the carb as the problem....

This is problematic because the RR (Peter Burgess) is in Alfreton which is about 30 mins drive from here. By the time I get there, everything will be nicely warmed up and there'll be nothing to diagnose. I guess - in fact I know - there'll be more local RRs, but I know that Pete Burgess is experienced with BL/Leyland stuff, and I'm a bit precious about letting other people tinker with my car :) I'd prefer to only get a known good guy loose on it :)

Definitely am now looking for a replacement HIF44 carb. I've done carb rebuilds myself before, and happy enough stripping down and reassembling with new components. I'm now on the lookout for whatever gets listed on eBay. I've seen that I can get a fully refurbed carb for a hefty price... I don't know how good (or otherwise) the pricey rebuild might be, so I'm looking to find a replacement HIF44 and buy a Burlen rebuild kit. If I get it all sorted, and then take a trip to Peter Burgess to get my overhauled one set up to see if that improves things over winter. Fingers crossed!

 

I reckon I'm going to have to do exactly this, so he can take a look at the problem when it's actually happening.  He's out on an industrial estate in the middle of nowhere.  I reckon I'll need to take a book.  And a big coat.

Edited by gutted, 02 November 2023 - 04:02 PM.

[gutted]

Are you certain that the choke is working correctly? It sounds as though it is running too lean at low temps and at first start-up when cold. That indicates that the mixture is not rich enough at initial start up and this will magnify the symptoms when the ambient temp is low.

If it's running fine when warm, it really has to be weak mixture when cold.

I have never understood the idea of warming the inlet charge with a heated inlet manifold when the best thing is a cold mixture for maximum efficiency/power. Many turbo cars have an intercooler to ensure that the air/fuel going in is as cold as possible and a 'cold air box' is usually thought of as a good idea in modified cars in general. I always disconnect the manifold heater pipes when working on later cars with this arrangement.

 

After someone pointed out (above) that the inlet will be plenty warm enough because it's attached to the exhaust - this is a really good point that I rather stupidly hadn't considered - I'm now ditching the idea of a heater manifold.

 

The choke definitely seems to do its job - on a normal day (not in winter) I'll use maybe half choke, maybe less, and will be running happily for maybe 10 mins before I no longer need choke.  When warmed, the exhaust gases are pretty much spot on for the emissions - last MOT I needed to bring it down a whisker as it was running slightly rich after the RR (but bringing it down a touch hasn't made a noticable difference to how it runs/drives, so I left it there and didn't turn it back up after the MOT).  Aside from setting the cold start at the carb, I can't make any adjustments to mixture without messing with the emissions - so the only thing that's left is to set up the cold start on the carb.

 

Thing is - when the problem is happening, I can give it absolutely everything on the choke and it doesn't improve things.  Lkewise I can put the choke fully in, and things don't get better.  I know that in general the choke is doing something because it makes the car easier to start on a normal morning, and I can smell from the exhaust that the choke is out.  Whether it's doing exactly what it should?  That's another matter - I don't know.  Perhaps not?