Hot Running Issues (and a bit of cold too...)

thomsonaj

New Member
Hi All,

The harsh Glasgow winter hasn't exactly been kind to the old girl and I'm experiencing a few issues when running from cold-poor idle, lumpy running and long warm up.

This clears after 1-2 mins of running and she runs fine on minimal choke, until the needle starts moving off of dead cold, it then deteriorates to the point where it doesn't run. The revs drop, power becomes virtually non-existent and eventually she stalls. I think it could be a carb tuning issue (i.e I've done it wrong) but I'd appreciate any input from people who've experienced good running for 3-4 mins in between cold and hot and garbage either side!

Many thanks, as always,
Sandy
 
When I was running SU's in good tune I had the same experience and I would find in winter stalling for the first 2 to 3 kms was common.
I would guess that carb leanness is the culprit however this symptom is by no means out of the ordinary in P6B's.
Even when I switched to a 4 barrel Weber 500 there is still a hint of it, my conclusion is that it is probably just the head design and the inlet area that takes a while to heat.
Maybe this was the reason Rover introduced AED (auto Enrichment Device) on early cars but the un-reliability of that unit was such that it disappeared.

You may also have some contributing factors such as poor ignition leads?

Graeme
 
Long warm up could be the thermostat, and the poor running could be the carbs icing if you're driving at the time, or a lack of fast idle if you're stationary. What type of carbs have you got?
 
Hi both - thanks for your replies.

I had considered the thermo as it could be gubbed - i'll swap it out this weekend for the sake of a couple of quid.

Ignition leads are 9 months old so unlikely to be a suspect.

It's got HIF6s as far as I'm aware Harvey - what does carb icing entail?

Thanks again,
S
 
thomsonaj said:
It's got HIF6s as far as I'm aware Harvey - what does carb icing entail?

HIF6 are the better standard carb. Carb icing happens when driving away from a cold start up on a cold day the air going into the air cleaner is so cold that it freezes the carbs. You lose power, come to a stop with the engine stalled, open the bonnet, and see the carbs covered in frost. The heat then permeates up, thaws the carbs and away you go again.
 
Thanks for that Harvey, makes sense. Pretty sure it's not this, as the symptoms are there at a standstill. Fast idle is a potential - original owner lost/removed the idle adjustment bolt so having to use bodged ones that i'm not convinced are staying in the set positions.

Also noticed that the fuel overflow line was spitting out petrol - perhaps a sign of sticky/punctured float.

Thinking of taking the carbs off the car and stripping them inside this weekend - is this a big job? Seriously rotten forecast for Glasgow this weekend so definitely up for inside activity!

S
 
Hi Sandy,

By rights you should not see any fuel emanating from the overflow lines, especially in cold weather, so a float due for replacement looks likely. The choke seal when worn will also see the engine behave very badly, so again this is a possibility. Either way, rebuilding the carburettors is advisable.

Removal, overhaul and refit will take the best part of a day, especially if they are fairly grubby and lots of cleaning is involved.

Ron.
 
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