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| Re: Car Running Too Cold? |
Subject: Re: Car Running Too Cold?
by Dodgeman on 2011/5/23 12:55:28
Well, my 1932 Dodge 6 cylinder sedan uses an updraught manifold with a hot spot & my 1933 Coupe used a downdraught manifold with a hot spot.
From memory, so did my FJ Holden & every single carb Datsun I ever saw
This was all well before emmisions regulations came in.
One must ask the famous Julius Sumner Miller question, .... "Why is it so?"
Why did hundreds of auto makers, over a period spanning 80 years or more, include inlet manifold heating when they could have left it off, still [as you claim] provided perfectly normal engine operation, & saved a few sheckles on every engine that they produced.
Would it be the same reason that the thermostat was never eliminated either?
I speculated that the overcooling & the unsatisfactory running of the engine that is the subject of this thread were in fact separate problems.
The overcooling is, I believe, a thermostat problem that it easily fixed, but unsatisfactory stock engine performance, during a wet winter, when operated at low speeds in an urban environment may well be caused by the lack of fuel vaporisation resulting from the removal of the inlet manifold heating function.
I then went on to describe the two main refrigritaion principals that take place at the throttle plate & the resultant loss of fuel vaporisation.
These are
1. Latent heat of evaporation &
2. Temperature drop at the point of pressure drop.
I provided easily demonstrated examples of these principals. [Perspiring is an example of No. 1]
Some symptoms of this can be
1. Reduced power. [Due to the resultant lean mixture as seen by the combustion chamber]
2. Increased fuel consumption. [Due to the higher power settings required to maintain performance]
3. Backfiring through the carb. [again, due to lean mixture]
4. Possible carb icing, resulting in the blockage of some small air passages within the carb. [Fuel jets never block with ice, every mechanic should know that]This results in a rich mixture as a result of the emulsion jet no longer receiving sufficient air, or indeed, any air at all.
A byproduct of this is the reduced atomisation of fuel as it is passed into the airstream from the discharge nozzle because it is not being 'premixed' with air. This in turn makes the problem of overfueling with liquid fuel even worse as the hot spot is no longer hot.
These problems will be greatest in winter, particularly in high humidity conditions such as fog or mist.
They will also be induced at high vacuum settings such as at modest cruise speeds with very low throttle opening.
In warmer temperatures, particularly a hot summer, all of these symptoms may well be non existant as the ambient temperature can easily be high enough to negate the effects completely but right now it's winter in Australia [or soon will be] & it's been wet & bloody cold, just the right conditions for the problems being experienced.
Higher speed engine operation & sub zero temperatures will often overcome some these problems due to higher gas velocity in the inlet manifold, lower vacuum figures & a low humidity due to the sub zero temperatures.
That's my reasoning, but am looking forward to a properly researched counterview instead of a lot of running off at the mouth.
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