BMC ‘B’ engine

[crankedup5]

When I recently purchased my campervan the previous owner did advise me that although the engine started from cold very readily and easily, not so from hot engine. He said it is very reluctant to start when the engine is hot, suggesting heat soak.
My guess is that fuel vaporisation could be the issue, although I have yet to experience the problem myself as only took delivery today! The engine is in good order with only 40,000 miles up since new in 1965. It’s the 1623cc version. At some point it has been fitted with a single SU carb’.

What other issues may cause the problem? If it is petrol vapourisation I’m not at all sure what steps I can take to ease / resolve the issue.

The camper is a Austin (forward cab) cotswold. Thanks for any comments / advise.

[Scrump]

As Daimler said it could be fuel or spark related.
Need to see if you can discover which it is and then go from there.

[hidetheelephants]

crankedup5 said:

When I recently purchased my campervan the previous owner did advise me that although the engine started from cold very readily and easily, not so from hot engine. He said it is very reluctant to start when the engine is hot, suggesting heat soak.
My guess is that fuel vaporisation could be the issue, although I have yet to experience the problem myself as only took delivery today! The engine is in good order with only 40,000 miles up since new in 1965. It’s the 1623cc version. At some point it has been fitted with a single SU carb’.

What other issues may cause the problem? If it is petrol vapourisation I’m not at all sure what steps I can take to ease / resolve the issue.

The camper is a Austin (forward cab) cotswold. Thanks for any comments / advise.

Is there an insulating piece between the carb and the inlet manifold? Often there's a plastic or tufnol spacer to avoid heat soak. Fabricating a heatshield between the carb and the exhaust manifold will help too. To an extent it's an inevitability with a forward control vehicle, the engine space generally isn't as well ventilated and modern fuel is a lot more volatile and thus prone to vapourisation.

[Rob Dicky]

Does it have an electric fuel pump?
This should fill the carb fuel bowl on switching on.

[Maxdecel]

crankedup5 said:

At some point it has been fitted with a single SU carb

I would've assumed by the manufacturer, year & engine that would be OE fitment ?

[RichB]

anonymous said:

[redacted]

This, change the condenser (a 50p component), then fit a new coil (or swap one from a car with a known good coil).

[Paynewright]

Has it got the one piece cast inlet / exhaust manifold like the mini? On my mini (A series I know) I used a water heated inlet manifold from a MG Metro. I wonder if you can get a separate inlet manifold?

[838HNK]

Some A series and B series have a metal plate to deflect heat of the cast iron exhaust ....

[Keep it stiff]

As suggested by others, far more likely to be related to electrics or carb maintenance than have anything to do with lack of heat shield or vapourisation theory.

[Huntsman]

9/10 carb faults ard electrical!

New condsensor, the Swiftune one seems very good. Now coil.

Dont faff about with secondhand coils and £3 Chinese condensors.

[Error_404_Username_not_found]

Huntsman said:

9/10 carb faults ard electrical!

New condsensor, the Swiftune one seems very good. Now coil.

Dont faff about with secondhand coils and £3 Chinese condensors.

This...
Distributor Doctor sells good parts for points ignition systems.
Avoid rotors with rivet centre contacts (they're usually black and always rubbish). Use DD red rotor.
Check the wiring inside the distributor too. It can be a mite fragile.
Ultimately you could fit electronic ignition, Accuspark or something. Most claim to be fit-and-forget and some are excellent but, with only a little care and maintenance, points ignition systems are simple, robust, effective and very reliable.

[Huntsman]

Error_404_Username_not_found said:

This...
Distributor Doctor sells good parts for points ignition systems.
Avoid rotors with rivet centre contacts (they're usually black and always rubbish). Use DD red rotor.
Check the wiring inside the distributor too. It can be a mite fragile.
Ultimately you could fit electronic ignition, Accuspark or something. Most claim to be fit-and-forget and some are excellent but, with only a little care and maintenance, points ignition systems are simple, robust, effective and very reliable.

Totally right.

I recently had a heat soak problem with a Powerspark, I'd done a poor job of applying the conductive paste and about 30 minutes in it gave up.

I reverted to points and £3 condensor that last about an hour. Replaced condensor with the Swiftune one and it ran a dream.

[harrycovert]

Also check that its not running rich that can cause hot start problems with SUs.

[crankedup5]

Many thanks to all contributors for great advise, I have a good plan of action to work from now.