Throttle plates for individual throttle injection

[Jon V.]

Rich Wrote:

> If you've got access to machining facilities, how about getting a pair of
> old Weber DCOE or Dellorto DHLA carbs, machine off all the unnecessary stuff
> to just leave the front 2 inces or so:- mounting flanges, throttle plate
> assemblies, air bypass channels (if fitted) etc.
> The advantages are: cheap! and will fit any engine which has a DCOE/DHLA
> sidedraught manifold available, either as OE or aftermarket, that covers
> virtually all 4-cyl. examples!

OK, OK, I've gotta cut in right here and say something... 

Don't get me wrong, I think your idea is very workable... even for someone
like me. I've got some machining facility access (I've got a small mill
and lathe I don't know how to use right) and I'm sure I could do exactly
what you suggest, but... BUT...

Hang on, I gotta calm down here... OK, I'm ready to go on.

If I could find a "cheap" set of Del'orto carbs and manifold, the last
thing I would do is hack into them! Where I come from, a USED set of
45MM  Del'ortos (the size recommended for this engine) with the right
manifold for my engine cost over $900 US, Used and NOT rebuilt... Now,
I'll admit that I didn't do MUCH looking, but I've got one company that
would LOVE to sell me a pair of 45MM Del'ortos with manifold... for $1400
US!

So, either I want your bank account or I want your source for carbs...
'cause AFAIK I could buy a whole damn car for the price of a set of those
"cheap" carbs that you are talkin' about. Or maybe 1.4KUSD IS cheap, in
which case I'm gonna... gonna... I don't know what I'm gonna do but I damn
well *know* it won't be *that*... probably cotton balls soaked with
gasoline held in front of the cylinders or something.

Maybe we're talking about different parts? I sure's sh..ope so, 'cause if
we ain't I gotta revise my budget numbers. Hell, I could probably get
$300-500 for my current carbs and manifold in their current condition... I
won't be cutting into them either.

I don't know about the webbers... I had a pair on a VW van once, and they
worked fine, but I got them with the vehicle...

Now, I could sort of see spending $400 or so for a "good" throttle
assembly, even used... but there ain't no way in nothin that I'm gonna
spend $1400 and then turn it into a pile of scrap zinc. Nope. Not gonna
happen.

> The injector mounting is a bit more tricky -
> the easiest route normally is to weld machined injector bosses into the
> manifold runners and fabricate/adapt a fuel rail structure. The throttle
> position sensor pot needs to be mounted off the end of one of the throttle
> spindles - again fairly simple stuff.

That stuff sounds fairly simple, and I'm sure I could handle it.

Actually, I liked a lot of the ideas presented. I think the motorcycle TB
assy is probably too small in the throat, but that was the idea I liked
best.

I actually think that for the level of effort and expense that I (in my
undoubtedly massive misunderstanding of what your suggestion actually
entails) see in what you are talking about you could almost build a
complete throttle assembly from scratch. I was blathering at a friend of
mine a while ago and we managed to delude ourselves into thinking that
what would be neat is a voice-coil operated throttle assembly... basically
a block of aluminum, cut in half, clamped together, bored to the proper
size throat, opened back up, a chamber hollowed out with an end mill, a
thin slot cut across the throat, a thin plate cut in a sort of g
shape positioned and pined so that the arm could be pushed on to
swing the plate out of the throat, and a speaker voice coil assembly and
spring arranged to link to the end of the arm... it would be cheap
($50/cyl?) and  you could probably swing the throttle full-cycle at up to
about 70Hz or so if you wanted and had a big enough amplifier driving it.

Thats the sort of thing that is *much* easier with a CNC mill, CAD
software, and a lot of software... none of which I really have or at
least know how to use, but if the alternative is spending $1400 to shred
somebody else's treasure, I'll bloody well get it. Sorry, raving again...

I think it would be a neat addition to an EFI system... you actually
control the throttle, instead of trying to sense its position and control
your actions based on that. You then have control over the MAP, and you
can predictively manipulate the fuel and the air. Besides, it allows the
whole engine to be controlled with the same serial cable. :-)

Anyway, pie in the sky bs, I know... the odds of something like that
actually *happening* are about 1 in 32,000... but it is a LOT more likely
than my cutting up... sorry...

Anyway, I'm sure I've leapt into a big massive misunderstanding with that
one... and I sure hope that in the process of slamming me against the wall
for being so ignorant someone will throw in a token "why"... I live for
those.

> I have gone through this process for a Ford 2L SOHC Pinto, got the manifold
> with injector bosses, cut down the carbs etc. - sadly never got the EFI
> finished!

That is sad... those were surprisingly good engines, though most people
are loathe to admit it. I had a friend who used to race pintos... he had a
blast, and probably spent 1/4 of what the "real" race car owners he ran
against spent.

> If anyone is interested, I could try and do some pics. I have drawings of
> the throttle pot mounting parts to fit Webers.

I would be interested, but I don't know what that's worth.

-Jon

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