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+--- Thread: 22FZB (/showthread.php?tid=2546)
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22FZB - bob46320 - 23-03-2019
My 1932 RN is pretty bog standard with a 22FZB mazac carburettor except that I have a 4 blade export fan. Living in SW France, we get both hot weather and challenging roads. Today, its only about 14 deg C, but climbing a 6mile long hill in second for most of the way was a not an uncommon challenge. Towards the top the engine started to miss a bit, but we made it and popped back into top gear and the engine cooled down a bit. When the engine misses, I am pretty sure its down to vaporisation. The radiator is newish, the head and block all clean, ignition sounds about right but never been able to check the dwell angle of the points.
The RN has a front tank gravity feed that gets pretty warm from the engine heat.
Any ideas how to cure this ?
BobH
RE: 22FZB - JonE - 23-03-2019
I'm sure others have put a shield between the carb and the exhaust... has yours got anything there?
RE: 22FZB - bob46320 - 23-03-2019
the exhaust is some way away from the carb. I have to admit, I don't have the flitch plates fitted as they don't fit without some serious re-shaping. As you probably know, the 22FZB is an updraught and is below the manifold.
Bob
RE: 22FZB - Nick Turley - 23-03-2019
I think you do need the flitch plates Bob.
RE: 22FZB - Reckless Rat - 23-03-2019
Since fitting an export fan to my RP I seem to have eliminated a problem similar to yours, Bob. However the SU on my car is more exposed to the draught from the fan compared to where the 22FZB sits. I used to run with the bonnet half open on hot days when climbing, which did help. On a long slog uphill it will get mighty hot under there which is no doubt causing you some vapour lock problems. Another option is a fibre block or extra gaskets between the carb and the manifold to reduce conducted heat.
RE: 22FZB - bob46320 - 23-03-2019
I would like some multiple temperature sensing to see where the heat is coming from, manifold, bonnet heat, fuel pipe temps but am struggling with some micro computer kit to get it to read sensible results. Could be an interesting project for all sorts of things.
Bob
RE: 22FZB - MartinH - 24-03-2019
I find that one of these cheap IR thermometers useful for finding the hot spots under the bonnet.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F153304289351
RE: 22FZB - bob46320 - 24-03-2019
Thanks Martin, but I want to see the temperatures when the problem occours - that would be whilst driving along the road.
RE: 22FZB - John Mason - 24-03-2019
Rather than making a shield to keep heat away from the carb( you state that your carb is some way away from the exhaust) could you make an arrangement to duct cooler air to the carb and fuel line. Just trying to think outside the box.
John Mason.
RE: 22FZB - Howard Wright - 24-03-2019
Hi Bob
If your fuel line is like mine on the RK it passes pretty close to the exhaust as it winds its way to the carb. I've wrapped my exhaust in heat shield fabric (off a well known auction site!) in the hope that this will prevent vaporisation. Not fully tested yet as the car is only just complete and the weather has not been warm enough.
Cheers
Howard