Vapour Lock

[Ian Williams]

Yes R I agree, although some logic may dictate that the closed end should be at the front those I have see appear to be designed to fit the opposite way round. To be fair if the bonnet is bolted down as intended there is little risk of it taking flight.

[Mike Costigan]

I'm pretty sure everyone I've encountered has had the closed end at the rear; as Ruairidh points out, the drillings for the horn mounting usually dictate which way round it goes. With the open end at the front it simplifies removal of the bonnet.

[Charles Levien]

We took the bonnet off the Nippy over the Grossglockner many years ago, drove with it standing on my passenger's lap as the car was jammed with luggage!

I think Recks is right, you need the hot air to escape somehow. Failing that, the exhaust must surely be the biggest contributor. Have you tried binding it in exhaust wrap? (eBay) That might shave a few degrees off and looks quite 'period'.

We went over the Grossglockner in 2017 and experienced similar problems. In fact we had to stop so frequently we were playing leapfrog with a cyclist. Can’t remember who got to the top first but we did pack some snow around the pump as we neared the summit.
The following day, I checked the carb ( 1” SU.) and found an air leak between float assembly and the main body. When this was nipped up our overheating problems vanished.
So I would say that running a tad weak could be a factor in overheating and worth looking at.

Charles

[bob46320]

Hmm! The plot thickens.

[Dave Mann]

    You don't have to take the whole bonnet off Bob which would draw the constabulary's attention to your illegal activity.

[bob46320]

Dave - I see your fuel pipe coil is in the vertical, but tell us more about what you have done to your carburettor. Oil breather and filter on the air intake and have you added a choke butterfly ?

[Dave Wortley]

Thank you for the photos including the ones on your website Duncan. Lovely!

[Dave Mann]

       
The intake pipe has a hose to the valve chest cover for crankcase ventilation and a choke flap which uses the original disabled choke flap spring.

[bob46320]

How thick do you wrap Exhaust bandage ?

[Chris Garner]

I've just remove bandaging from the tail of an exhaust system right up to and including the manifold. I was appalled at the corrosion underneath. Hate the stuff.