Bob:
My 78 had all of the emission equiptment removed by the previous owner. He
was also the "master mind" behind the Zenith to HIF switch. Fortunately,
at 25 years old I was able to register it as a "Historic" vehicle thus she
is except from auto inspection here in NJ. This also permitted me to pick
up full coverage "antique" insurance from a nice outfit that did not have a
miles per year limitation. Nice!
I just had the HIF rebuilt and the valves adjusted (rebuilt head by former
owner) and she's doing fine. I find it amazing all the waves, beeps,
smiles, and ocassional flirts the vehicles seems to produce. Best 2800. I
ever spent.
Ted
----- Original Message -----
From: "Bob Howard" <mgbob@juno.com>
To: <wa2mgb@optonline.net>
Sent: Friday, January 24, 2003 3:19 PM
Subject: Re: HIF vs Zenith Carbs
> Congratulations. The 78 is a good car; MG worked out by 1978 the
> problems it created by raising the car to meet the US standards and
> increasing its weight with the rubber bumpers.
> Changing back to the HIF carbs is a good thing too. The ZS carb
> wasn't that bad---but the engine did suffer from poor manifold design and
> emissions strangulation, and the the older HIF carbs would refit to
> benefit performance. While your car may not now pass emissions with the
> test-at-idle test used in 1978, it will pass today's
> rolling-on-treadmill-at-35 mph test that we use here in CT, and will pass
> easily. A poor test used then caused MG and many other manufacturers to
> adapt a teach-to-test approach rather than an overall clean air approach.
> We're wiser now, 20 years later.
> Yes, they are single-barrel, in the sense that there is only one
> venturi. The Brits tended to use two singles while Americans used one
> two-barrel. For an inline engine, the two singles do work better. An
> alternative often found on MGBs is a single Weber, but with some pretty
> elegant intake manifolding.
> Why two? It's not that one can't supply the air/fuel mix, but rather
> that if you stand at side of engine and imagine the air flow in and out,
> you will see that the air flows from front carb pretty directly into
> cylinders 1 and 2, and from rear carb into 3 and 4.
> I suspect that there is an economic reason too, that being that labor
> costs in USA are historicly higher in relation to parts costs, so
> Americans tend to do simpler labor fittings with more expensive parts.
> F'rinstance, in US we adapted automatic chokes early on. The assembly
> line guy could just bolt on a complete assembly carb, rather than bolting
> on a carb, fastening on a cable clamp, snaking a wire, hooking cable to
> dash, etc.
> You will like the HIFs. They seem complicated, but they really do make
> a lot of sense and once you get the hang of them you will find them quite
> fine units.
> Bob
> '72 GT (with two HIFs)
> '52 TD (with two HSs)
>
> On Fri, 24 Jan 2003 13:28:00 -0500 (Eastern Standard Time) theodore
> anderson <wa2mgb@optonline.net> writes:
> > Hi:
> > I recently became the proud owner of a 78 MGB. My mechanic
> > informed me
> > that the original carb was a Zenith Stromberg and that alterations
> > had been
> > performed so that the configuration is a pair of SU HIF carbs.
> >
> > Dumb questions:
> > 1. Is this change a good thing?
> > 2. Are these single barrell carbs?
> > 3. Why would two carbs be desirable on a 1800cc engine?
> >
> > By the way, the whole car runs great. Amazing what you can buy off
> > eBay.
> >
> > Ted
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