Always Remove and replace Variable Venturi Carbs with Standard Holley or Edelbrock units
#1
02-08-2015, 10:46 PM
Always Remove and replace Variable Venturi Carbs with Standard Holley or Edelbrock units
Dear Ford enthusiast.
I see many people asking questions about VV Carbs.
I can advise you to remove the device and the manifold and
purchase a new Edelbrock Performer manifold and suitable
carburetor in all cases. NEVER TRY TO "FIX" a VV unit.
Ford itself will admit the product was never "right". Here is why:
When the carb was put on cars and trucks they needed to connect
the carb to several computerized " decisions" for things like cold idle
and cold mixture ( like a choke function ) and they chose to do it
in a way where the software gets confused about when the car is
"READY" to drop the choke. Being the fuel worried car company the
engineers working on the project selected an "early" dropping of the choke
after fast idle. In my case this meant that after you get to the end of the
street the computer stops the choke function. It watches the brake
pedal . When you are stopped at the stop sign you are idling and apparently on the choke. When you move your foot from the brake to
the gas pedal and apply pressure the computer drops the chock function which is a extra fuel solenoid, and this causes the motor to instantly
become LEAN which makes the engine stall. Then you are stopped in the intersection with oncoming trucks ready to kill you and you have to pop the car into neutral and start the car and return to DRIVE before they hit you.
This happened on the the first test drive when my mother insisted I go to a Dodge Dealer to look at a low priced "creampuff " with low miles and it was a Mercury Colony Park wagon with low miles. It was summer time and about 70 degrees out.
We started the car with no problem and it ran swell, we pulled out into the
main road and drove about a mile down the road. I turned into a side road to return to the dealer and turned around in a culdesac. I waited at the stop sign for traffic to clear so I could turn right and go back to the dealer.
When traffic opened up I lifted my foot from the brake and pressed the gas, the car advanced about 10 feet into the busy 4 lane and died immediately. I hurriedly re-started it and returned to the dealer.
I told my mom not to buy the car, it had something wrong.
She of course returned the next day and bought it and it nearly killed then
for about 2 years. Finally the transmission failed.
At that point it was clear the Aluminum Manifold was also rotted out
and the dealer said "they all do that".
We took out the failed transmission and engine as a unit and installed a
1973 351W and FMX tranny from a Mercury Monetgo with an Edlebrock Performer manifold and a Holley / Ford carburetor. This motor had 150,000 miles on it, but no cylinder ridge at all. We pushed the pistons up and out with our hands! We cleaned, broke the cylinder wall glaze, replaced one piston and did the valve guides. We replaced the bearings, bolted it back into the car and it ran great. The driveshaft attachements we got from the same year Cop Car and they bolted right up to the Differential. Apparently the cop cars used the old FMX transmission with the 351W too.
This combination stayed with the car for another 150,000 miles.
It turns out when the Ford engineers could not get the temperature
and fuel system to run right in the software of the computer they just
threw up their hands and shipped bad product.
There is no value in keeping the VV system as it can never be made to run correctly. The software is not there and you are not likely to become a better programmer than Ford engineers and solve the problems they could not solve.
I see many people asking questions about VV Carbs.
I can advise you to remove the device and the manifold and
purchase a new Edelbrock Performer manifold and suitable
carburetor in all cases. NEVER TRY TO "FIX" a VV unit.
Ford itself will admit the product was never "right". Here is why:
When the carb was put on cars and trucks they needed to connect
the carb to several computerized " decisions" for things like cold idle
and cold mixture ( like a choke function ) and they chose to do it
in a way where the software gets confused about when the car is
"READY" to drop the choke. Being the fuel worried car company the
engineers working on the project selected an "early" dropping of the choke
after fast idle. In my case this meant that after you get to the end of the
street the computer stops the choke function. It watches the brake
pedal . When you are stopped at the stop sign you are idling and apparently on the choke. When you move your foot from the brake to
the gas pedal and apply pressure the computer drops the chock function which is a extra fuel solenoid, and this causes the motor to instantly
become LEAN which makes the engine stall. Then you are stopped in the intersection with oncoming trucks ready to kill you and you have to pop the car into neutral and start the car and return to DRIVE before they hit you.
This happened on the the first test drive when my mother insisted I go to a Dodge Dealer to look at a low priced "creampuff " with low miles and it was a Mercury Colony Park wagon with low miles. It was summer time and about 70 degrees out.
We started the car with no problem and it ran swell, we pulled out into the
main road and drove about a mile down the road. I turned into a side road to return to the dealer and turned around in a culdesac. I waited at the stop sign for traffic to clear so I could turn right and go back to the dealer.
When traffic opened up I lifted my foot from the brake and pressed the gas, the car advanced about 10 feet into the busy 4 lane and died immediately. I hurriedly re-started it and returned to the dealer.
I told my mom not to buy the car, it had something wrong.
She of course returned the next day and bought it and it nearly killed then
for about 2 years. Finally the transmission failed.
At that point it was clear the Aluminum Manifold was also rotted out
and the dealer said "they all do that".
We took out the failed transmission and engine as a unit and installed a
1973 351W and FMX tranny from a Mercury Monetgo with an Edlebrock Performer manifold and a Holley / Ford carburetor. This motor had 150,000 miles on it, but no cylinder ridge at all. We pushed the pistons up and out with our hands! We cleaned, broke the cylinder wall glaze, replaced one piston and did the valve guides. We replaced the bearings, bolted it back into the car and it ran great. The driveshaft attachements we got from the same year Cop Car and they bolted right up to the Differential. Apparently the cop cars used the old FMX transmission with the 351W too.
This combination stayed with the car for another 150,000 miles.
It turns out when the Ford engineers could not get the temperature
and fuel system to run right in the software of the computer they just
threw up their hands and shipped bad product.
There is no value in keeping the VV system as it can never be made to run correctly. The software is not there and you are not likely to become a better programmer than Ford engineers and solve the problems they could not solve.
#2
03-22-2015, 10:05 AM
#3
03-22-2015, 10:47 AM
Sadly you missed the purpose of my post.
If you read the details, it was not a diaphragm issue that
makes the VV carb a Killer. It is the software that dumps
the fuel enrichment solenoid when you press the gas pedal
during a cold run from your house to a stop sign. The software is not
changeable and not worth changing. The cost of digging up the needed
tools from the 1980's era microprocessor programming world would surely be a waste of time compared to swapping in a nice 1985 5.0 motor, which would run very well
or simply going to the 2V Motorcraft 2100 unit which works well.
My advice stands- the VV is a killer and it should always be replace to protect the
"average" drive from its vile tricks.
If you read the details, it was not a diaphragm issue that
makes the VV carb a Killer. It is the software that dumps
the fuel enrichment solenoid when you press the gas pedal
during a cold run from your house to a stop sign. The software is not
changeable and not worth changing. The cost of digging up the needed
tools from the 1980's era microprocessor programming world would surely be a waste of time compared to swapping in a nice 1985 5.0 motor, which would run very well
or simply going to the 2V Motorcraft 2100 unit which works well.
My advice stands- the VV is a killer and it should always be replace to protect the
"average" drive from its vile tricks.
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