[DML] Re: Fuel Metering
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[DML] Re: Fuel Metering

Be nice (how did the moderator let your final paragraph through?)

This whole newsgroup is dedicated to living the turn of the decade.
Some mid to late 80's BTTF, but the vehicle we all know & love is
1970's engineering at it "finest."

Let me jump straight to the point: The point is options. Some people
prefer EFI. Some people prefer carburetion (NASCAR, for example --
every single car racing around a track today burns a carb. Carburetion
is good enough for NASCAR, it's good enough for me). If Mao Tse Tung
ran the hobby, our vehicles would all be identical. He doesn't, and
the aren't. If you prefer mechanical injection, great: your PRV is
already so equipped -- drive happy. If you prefer EFI, great: modify
your PRV accordingly and drive happy. If you prefer carburetion,
great: chuck one on your PRV and drive happy.

I do object to your assertions that carburetion has no redeeming
qualities as a fuel metering method. I've listed a few off the top of
my head at the end of this message.

My fuel metering method may not meet your taste, but I am far from
stupid. The decision to use it was made on the basis of knowledge. I
understood fully what I was jetisoning, and what its replacement would be.

Given the option (like many DeLorean owners, BTW -- probably more than
have gone EFI), I chose carburetion.

Some benefits of carburetion:
- Central metering point -- all cylinders are guaranteed to receive
the same fuel/air mixture (throttle body injection has this same benefit).
- Extremely gentle fuel delivery -- engine vacuum alone pulls fuel
through the jets. Fuel pump is gentle too (about 4-6 PSI). Every
single component, including hoses and filters, is not subjected to
pressure, clogging, etc that forced injection is liable to.
-Accessibility -- carburetors are very small. They also are centrally
located (far away from spark plugs, ignition distributors, bolt on
accessories, etc). There simply is nothing rendered inaccessible by a
carb. Note also that carburetor installation or removal takes only a
minute or two -- three or four nuts (depending on the model) are all
that hold it to the manifold. Carb gaskets aren't glued down either.
- Reliability -- with a simple carb (translation: not Holley or
Rochester), there basically is nothing to fail. There also is nothing
to re-adjust. Jets are a particular size -- once installed, they can
not change. Idle mixture is adjustable, but the needle screws usually
have springs under their heads to hold whatever setting is chosen
thereafter. Note that this benefit does depend on the model carb
chosen (many turn of the decade carbs added all sorts of solenoids,
externally activated valves, and even variable venturi sizes to meet
emissions and fuel economy mandates, but their earlier brethren --
which can and should be substituted -- were not so encumbered). 
- Options -- most carbs are interchangeable. If your vehicle came with
a manufacturer or model you do not like, simply substitute another. I
guarantee Douvrin never anticipated a motorcraft on one of their
engines! (Solex was the carb of choice).
- Do-It-Yourself installation -- no special skills or tools are needed
to install or adjust a carburetor. Usually a single flat wrench and a
straight blade screwdriver are the only tools necessary. You can use a
vacuum gauge to adjust idle mixture, but most owners do it by ear.
Holley/Rochester caveat applies here also.
- Low cost -- with simplicity comes lower cost. Not only is every
single component cheaper than anything you'll every but for fuel
injection, but there simply are fewer of them. A simple fuel pump, a
small cartridge fuel filter, and the carb itself -- that's it.

Re: Lack of 10 year old British automobiles -- what are you doing over
there to kill them? I still drive the same automobile I drove in high
school (1981 AMC). My 1985 F-150 just turned 215,000 on the odometer.
Oldest vehicle in my stable is a 1977 Lincoln -- same year model as
the school bus I'm donating to my church.

Of course all of the above are carbureted -- coincidence?

Bill Robertson
1981 AMC Spirit
1985 F-150
1988 F-150
1977 Lincoln Mark V (Blue)
1978 Lincoln Mark V (White)
1978 Lincoln Mark V (Silver)
1978 Lincoln Mark V (Primer)
1979 Lincoln Mark V (Blue & White)
1977 Loadmaster School Bus
ex 1976 Honda Civic (I sure do miss that little car...)

>--- In dmcnews@xxxxxxxxxxxxxxx, Martin Gutkowski <martin@...> wrote:
> On-the-road cars older than 10 years are RARE full stop here. We're  
> all on the lookout for the old K-Jet V6's and they're like hen's teeth  
> now. Later PRVs are ten a penny. I bought a 3 litre for £47... do you  
> want it? You'd completely stumped by all the funny wiry things all  
> over it and a complete lack of any adjustment screws south of the  
> throttle stop.
> I was replying to your comment about plenty of PRVs out there not  
> running CIS. Pre-EFI PRV cars are VERY rare, saying that "there are  
> plenty" is, as usual, just plain wrong.
> All "modern" PRVs run EFI and have closed loop idle control as part of  
> the main ECU.
> Stop making stupid arguments that benefit no-one. You have fun living  
> in the 70's but there's no reason to inflict that on everyone else...
> FWIW Chris will soon be living in the 90's (grin) with a 3 litre twin  
> turbo EFI PRV
> Martin
> #1484
> #11766
> ex #1458
> ex #4426
> Venturi Atlantique 300
> www.delorean.co.uk

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