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Old December 19th 07, 06:28 AM posted to alt.autos.corvette
Elbert
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Posts: 22
Default '84 crossfire to carburator conversion

On Tue, 18 Dec 2007 20:17:24 -0500, "Fixitman"
<fixitman333-at-yahoo.com> wrote:

>I've been restoring a 82,000 mile 1984 Corvette for over a year now. During
>this process, I've made it a point to know how everything works. The
>electrical system was hacked up pretty bad, so this was my primary concern.
>Unfortunately, the car ran very poorly, so I had to fix that first. I
>initially wanted to convert to carburation, but found the price-to-benefit
>ratio to be a negative value.
>
>On the plus side:
>1. The cluster only needs the ECM for fuel economy information. The rest of
>it will perform perfectly without the ECM.
>
>On the negative (note that the ECM will be effectively dead):
>1. The transmission TV cable (throttle valve system) can be adapted to a
>carb, but will be difficult to syncronise properly. Result- shift points and
>kickdown are never quite right.
>
>2. The TCC (torque converter clutch: overdrive) is controlled electrically
>by the ECM. Most aftermarket TCC kits are designed for off-road use, and can
>be a real PITA on the street. Leaving the TCC disabled means reducing fuel
>economy considerably above 45 MPH. Top speed will also be reduced.
>
>3. The stock distributor will not advance timing properly without the ECM.
>Improper timing advance = extremely poor performance. Early
>centrifugal+vacuum advance distributors will work, but not as well as the
>original system. Once again, it would lose some streetability.
>
>4. Emissions will be higher, because affordable carbs just aren't as
>effecient as fuel injection PERIOD. Emissions go up and fuel economy goes
>down, resulting in a loss of performance and "fun factor".
>
>I've been working on cars proffessionally for over a decade now. Once I
>realized just how much work was involved, and what I would lose, the
>decision was easy..... Fix The Crossfire. I later found that the fuel lines
>were severely corroded inside, severe enough to plug the fuel filter within
>a few days of replacement. I spent about $50 and about 5 hours bending and
>installing new fuel lines, and couldn't be happier. The '84 runs great, and
>gets 18-20 MPG (if I keep the pedal off the floor).
>
>If the only reason you're bent on starting this project is a cracked
>manifold, here is a cheap alternative:
>http://cgi.ebay.com/ebaymotors/Corve...spagenameZWDVW
>If it's still available Friday night, I'm going to buy it for a porting
>project.....
>
>Fixitman
>
> "Art" > wrote in message
. net...
>> Hello All Again,
>>
>> After doing tremendous research I think the conversion is not very

>difficult
>> as long as certain things are compromised. Please allow me to run these
>> things by everyone for comment.
>>

>



None of you guys have mentioned that there are a number of engine swap
harnesses out there that would allow you to swap something like a
modern tuned port or Vortec style engine over into this car, which
would include a new ECM. IF you determine which cars don't have
electronic shift and only have to deal with TCC control then that
would solve the shift business.

I realize that you have to know a great deal about car work to really
tackle one of these jobs, so that's a given.

As far as a TV cable with a Carb. The principle of the TV cable
adjustment is the same, whether its on a carb or fuel injected
car. The brackets are very similar. I don't see it being a problem to
adapt a bracket , or I believe B&M and others make one that would
work.

Don't have first hand knowledge of the TCC kits...they may suck don't
know. As stated there are kits out there. As I related swapping over
a 700R4 into an older car (ie older than an 84 vette) is real common.
I suspect there are a number of proven combinations for brackets and
TCC control.

If you run a carb, you throw the electronic distributor in the garbage
and get an old school HEI distributor (non ECM controlled)

I don't equate to emissions going up and performance going down.

You don't go down the road of a hybrid. You either go all the way with
a carb or go all the way fuel injection. Its also clearly a given that
fuel injection is by far cleaner, and more fuel efficient. Potentially
more power depending on the system, due to fuel control.
Meeting emissions requirements does not equal more power.

Yes its clear that fuel economy will not be improved by going to a
carb, but I'm not sure the guy cares about that.



So the idea is that the ECM only drives the mileage "computer" on the
dash. I personally don't think those things are accurate, and I could
do without that. Don't know what the initial poster's preference is on
this.

You can swap the intake, and install a carb, plus a non ECM
distributor and have a very decent performing car. Look into what
all the hot-rod guys are doing to make this happen.

Intake max $200.00
Carb $350
distributor $100
TCC control $75 ?

I don't agree with making this happen for $500 even if you
do the work yourself. But its very clear that this is somewhat
simple modification if one has basic mechanical skills.

So if you eliminate the distributor, and the fuel injection,
and if you don't care if the fuel mileage display works, what's
left that the ECM controls... just TCC? Which you can address.

I believe you could just remove the ECM all together, along with the
stock intake and fuel injection. Install an aftermarket carb and
matching intake, along with a old school HEI distributor and you would
be in business. Yeah its a given there may be some like issues, like
ign on at the distributor and TCC control. But these things are old
school issues that have been out in the hot-rod community
for some time.

Of course if you go old school, that opens the box to all kind of
proven engine combinations that make good streetable power and run
a carb, or even getting a Vortec 350 long block and use a carb for
power.

Like I said... I think a tune port setup is the ticket here, but it
depends on the owners ability and how much $$ he wants to apply.

If were to go to the trouble of going to a carb, I would change the
cylinder heads to something like a Dart Iron Eagle setup, run a
performer style dual plane if it will clear the hood or one of the GM
LT1 old school dual plane intakes, and a matching carb. I would put
that combination up against any cross fire. Carb setups are plenty
"streetable" .

There are any number of vehicle setups that one could replicate with a
GM 5.7 engine assembly. To be honest it would be near impossible to do
this even simply for under around $700. And that's someone who knows
how to do this work on their own.

I think you can easily get a clean running, very smooth drivable car
by going carburetor. Will it pass emission for that year model
vehicle...simply no!, will it outperform a cross-fire setup? maybe,
Will it be more fuel efficient, no! Can someone do this with basic
mechanical skills? yes. Is there value lost...yes if you want the car
to be stock. Will your accessories function, yes. Are there many
sources for modifications such as this, yes.

If I had a more modern vette would I change from fuel injection...no.
Would I consider moving to a more modern fuel injection system over
carb, yes. Why.. power. Are there plenty of parts available for such
a swap over to a carb, yes.

If you want a stock vette, then of course you would not want to do
this. You could easily make a swap like this work out and have a nice
drivable car that performs very well.

Does a 84 vette run a mechanical fuel pump, if not then that would
have to factor into a carb swap. I don't know what the fuel pressure
requirements for a crossfire is but I would guess around 13 or lbs
similar to a TBI. Of course with a carb you have to reduce that down
to somewhere around 7lbs.

Of course I would make some other adjustments related to emission
controls if I were to go carb setup. Yes you can make adjustments
that actually make the car run better.

If you have pass emissions then you had better play the fuel injection
game and see what your options are. If not then there exists a whole
panacea of options.


Does doing a modification like this increase the value or even
maintain the value, no. Unless you can repair the intake,you have a
dead car on your hands, then something that runs sales better than
something that does not.
-----------
Elbert


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