Monty2556
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| posted on 9/4/14 at 06:48 PM |
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Heater hose to Inlet Manifold
I've got a 1600 xlfow with a 32/36 inlet manifold. Whats the purpose of sending hot water through the inlet manifold? I've seen setups
with the inlet union blocked off at the manifold. I assume it's to heat up the manifold but surely the engine heat would achieve that on
it's own.
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coyoteboy
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| posted on 9/4/14 at 07:36 PM |
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Often used to prevent throttle/fuel freezing at very low temps.
Run with my tin-top one disconnected for 5 years no issues.
[Edited on 9/4/14 by coyoteboy]
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britishtrident
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| posted on 10/4/14 at 06:25 AM |
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Because carbuerretors evaporate at least some of fuel that goes through them they act as refrigerators, together with the effect of changes in
pressure due to the venturi effect this results in the air going through the carb dropping in temperature and in right atmospheric conditions will
lead to ice formation.
Note that this does not require the ambient temperature to be below zero a part from ambient temperature relative humidity is major variable to be
considered. In the damp UK climate sever carbuerrettor icing can occur at 10c ambient temperatures.
A heated manifold cost power because increasing the inlet temperature reduces the mass of air going through the engine however because the jet
sizes have been calibrated with the heating effect then running with out it will result in weak mixture which will cause hesitation, misfires and
result. In engine damage typically burnt exhaust valves.
More info http://en.wikipedia.org/wiki/Carburetor_icing
[Edited on 10/4/14 by britishtrident]
[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]
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r1_pete
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| posted on 10/4/14 at 07:26 AM |
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quote:
Originally posted by britishtrident
Note that this does not require the ambient temperature to be below zero a part from ambient temperature relative humidity is major variable to be
considered. In the damp UK climate sever carbuerrettor icing can occur at 10c ambient temperatures.
More info http://en.wikipedia.org/wiki/Carburetor_icing
[Edited on 10/4/14 by britishtrident]
Its a similar effect as, if you lick the back of your hand and blow on it, it feels cold despite the ambient temperature.
I've run crossflows in Cortinas, Escorts etc. back in the late 70s with and without the coolant flow, and never had a problem with icing, the
manifold will warm up due to being bolted to a hot lump of iron anyway, coolant flow just speeds it up a little.
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DIY Si
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| posted on 10/4/14 at 11:39 AM |
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I found that the spicier the engine, the more likely this is to happen. On my old stock 1275 minis, is was never an issue. Stage one tuned, never an
issue. With my almost race engine'd mini running a 48 IDA, it would ice up regularly and would be a bit of a PITA at times as it just
wouldn't run right. And due to the design of the manifold and the plumbing, heating the inlet wasn't a viable option. Despite painting the
manifold black in an effort to get it to absorb as much heat as possible, I did see ice on the outside of it at times, despite it being above the
exhaust.
Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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rusty nuts
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| posted on 10/4/14 at 05:57 PM |
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One thing to take into consideration is air locks in the cooling system . If your not using a heater it may be a good idea to run a horse from the
inlet manifold to the water pump inlet.
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Monty2556
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| posted on 10/4/14 at 06:17 PM |
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Thanks for all the advice. I've looked on Google as well and it seems that there's a wide difference of opinion. It varies from
"a heated manifold is essential" to "it doesn't matter". From what's been said on this thread I think I've
got the message.
Once again, many thanks
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