Updraft carbys
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Updraft carbys
I'm having a debate with a few lads over beers about what an updraft carby system is. Some claim it is to allow the mixing of warm air to prevent carby icing. Another claims it prevents an engine fire due to over priming.
Google and text books won't provide me with an answer. Are there any pruners who wish to share some wisdom?
Thanks
FTS
Google and text books won't provide me with an answer. Are there any pruners who wish to share some wisdom?
Thanks
FTS
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Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top. This had the advantage of never "flooding" the engine, as any liquid fuel droplets would fall out of the carburetor instead of into the intake manifold; it also lent itself to use of an oil bath air cleaner, where a pool of oil below a mesh element below the carburetor is sucked up into the mesh and the air is drawn through the oil covered mesh; this was an effective system in a time when paper air filters did not exist.
http://en.wikipedia.org/wiki/Carburetor
that is what you wanted right?
I think you'll also find that one of the main reasons aero piston engines (the flat ones) use updraught carbies is because of aerodynamic reasons - They need to keep the top of the engine as flat as possible so all the manifolding and so on has to go underneath.
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Oil Bath air cleaners
These type of air cleaners are used on down-draught carburettors as well as up-draught and do not need to be below the carby, but sit on top of the carby. The statement that engines fitted with up-draught carbys "never flood the engine" is not correct. The raw fuel just lies in the intake air line from the air cleaner and will still be drawn into the cylinder just as with a down-draught carby.
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Quite correct 'Old Fella' I agree both counts. Oil bath air filters have been around for both up & down draft carbies for some time. My Holden FC had an oil bath filter & it was fitted to the downdraft stromberg, untill I fitted tiwn carbies, extractors, stage 3 yellow terra head &lowered the old girl, the next stage was to get booked for having an unroadworthy car
.
Enter planes & girls, am paying for that bad mix forever!
'18W' I would say yr correct there the updraught carby was designed & fitted below the top of an engine (auto & aviation) to contain the overhaul shape/size of the engine to fit inside a streamlined cowl/bonnet.
CW
. Enter planes & girls, am paying for that bad mix forever!
'18W' I would say yr correct there the updraught carby was designed & fitted below the top of an engine (auto & aviation) to contain the overhaul shape/size of the engine to fit inside a streamlined cowl/bonnet.
CW
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Yeah Wally, my first car was a EK Station Sedan with the dual barrel stromberg and an oil-bath air cleaner; spent its early years in SW Qld where bitumen was not common. Replaced the aircleaner with a 'Sports' jobbie, added the stainless steel exhaust.....the mighty 138 grey motor and the 3-speed hydramatic went like a train for the 20-some years we had it. Traded it for $750 on a Datsun 260Z
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Oil Bath air cleaners
CW, both my TEA20 (Grey Fergie) and my 1937 Plymouth have oil bath air cleaners and both have the cleaner located higher than the carby. The Fergie uses an up-draught carby with the air cleaner remotely located with an air trunk to the air inlet on the carby and the Plymouth a down-draught with the air cleaner sitting on top, as was your Holden. Both are easily "flooded" if the applicable starting technique is not used.
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Yes.. The internet 'as we know it' - post military stages - came about in 1991 or something, if memory serves me right.
I started on the net in about 1995, yes, i was in year 1, 5 years old.
Our first PC, a gateway with windows 95 on it.
fun stuff
I started on the net in about 1995, yes, i was in year 1, 5 years old.
Our first PC, a gateway with windows 95 on it.
fun stuff
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'Torres' you just bought tears to my eyes with that last piccy. Not seen nor do I want to 3X2" SU's in a long time That looks like a 3.8 E Type also, might have had 1 3/4" SU's not too sure but the 4.2 had the 3" jobs.
I used to tune mine about every second W/E But we are now talking side drafts, Webbers the go there
CW
That looks like a 3.8 E Type also, might have had 1 3/4" SU's not too sure but the 4.2 had the 3" jobs.I used to tune mine about every second W/E
But we are now talking side drafts, Webbers the go thereCW
Capt Wally
I do feel sorry for you for the Poms never understanding the KISS(Keep It Simple Stupid) principle. I would have fabricated a single 4 barrel manifold for that Jag, bolt on a 600 vac/sec Holley 4 barrel and go boogie because it would have turned it into a beast. And you could have your weekend off without tuning the damn thing every second.
And if that don't work, put a Chev in it like everyone else do these days
You wanna rev it, Chev it! Can't afford, it Ford it!
And if that don't work, put a Chev in it like everyone else do these days
You wanna rev it, Chev it! Can't afford, it Ford it!
'66 Series 1 4.2 2+2.
They are triple 2 inch SU's. The twin Weber conversion is $4K plus - besides, I like originality and after 42 years, it's still the quickest car in town.
The Ferguson TEA20 restoration back to as new is almost finished.
I can't find out why carbys evolved from up draft, to down draft. However I suspect a major factor may have been bonnet alignment in the days of side valve engines - an updraft carby was below the top of the engine, allowing a lower bonnet. Once valve gear went on top of the head, and carby height reduced, down draft carbys became the norm.
With horizontally opposed aircraft engines, I assume up draft carbys (under the engine) resulted in a flatter cowl and better pilot visibility.
They are triple 2 inch SU's. The twin Weber conversion is $4K plus - besides, I like originality and after 42 years, it's still the quickest car in town.
The Ferguson TEA20 restoration back to as new is almost finished.
I can't find out why carbys evolved from up draft, to down draft. However I suspect a major factor may have been bonnet alignment in the days of side valve engines - an updraft carby was below the top of the engine, allowing a lower bonnet. Once valve gear went on top of the head, and carby height reduced, down draft carbys became the norm.
With horizontally opposed aircraft engines, I assume up draft carbys (under the engine) resulted in a flatter cowl and better pilot visibility.
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'sms777' all true but yr talking about bastardizing a fast becoming rare car. Sure the Chev conversion would kill the original Jag 3.8/4.2 in a lot of ways but it wouldn't be a Jag after that & you couldn't give it away to an enthusiast
. I recall a pilot here who had a beautiful series two that was stock accept for the Toyota box, he did eventually sell it but was hard to do so after being called a 'butcher'. I did love the feel of those 245 horses tho, all being fed by my lovingly cared for SU's, at great expense of course!
Edited for 'torres' I wasn't too sure that the early 'clean' rocker covers where also 4.2's Why sell it when it's almost finished?
............yeah I know it's a thread drift but how much can ya chat about up draught carby's anyway?
CW
..........You wanna rev it, Chev it! Can't afford, it Ford it!, This bit I laughed at
. I recall a pilot here who had a beautiful series two that was stock accept for the Toyota box, he did eventually sell it but was hard to do so after being called a 'butcher'. I did love the feel of those 245 horses tho, all being fed by my lovingly cared for SU's, at great expense of course!Edited for 'torres' I wasn't too sure that the early 'clean' rocker covers where also 4.2's
Why sell it when it's almost finished?............yeah I know it's a thread drift but how much can ya chat about up draught carby's anyway?
CW
..........You wanna rev it, Chev it! Can't afford, it Ford it!, This bit I laughed at