84 crossfire switch to 4bbl carb
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Joined: Apr 2018
Posts: 60
Likes: 6
From: Plainwell MI
84 crossfire switch to 4bbl carb
Been thinking about this. Yeah I know the benefits of F I. I have access to a decent aluminum 4bbl intake and carb. I know that a TV cable bracket is made for this switch. Just curious if there is a sticky thread for this here? Has anyone here done this? I believe the only thing the ecm controls is spark and fuel mix for the F I. I am old school enoough that I am far more comfortable with a 4bbl than F I. Any help is welcome.
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
Likes: 1,174
From: Southlake, TX
Your ECM is the heart of the 84. It controls LOTS. You carb is set up to essentially be a mechanical device but your FI is all about sensors and command guidance, Throttle positions sensors, Idle control, MAP and not to forget the O2 sensors.
As you stated that any opinions are welcomed.... unless you are looking for a very involved project, you can dial in the XFire to be a very squared away engine. I was intimidated when I first had mine but grew to love it---fast.
Racer
Joined: Mar 2018
Posts: 386
Likes: 75
From: Swartz Creek MI
my 84 stumble when warm I change the 1 map sensor so far it doesn't try stall after shutting it off at a store and restarting it and taking off and stopping, most time the 2 coolant sensor is the problem so I changed all three of them even 3 O2 sensor
Last edited by fparkin; Jul 13, 2018 at 07:43 PM.
Thread Starter
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Joined: Apr 2018
Posts: 60
Likes: 6
From: Plainwell MI
Not intimidated by it. Put my first engine together in 1971. A 454. did everything. but the shortblock. Cam, heads, intake, carb, headers. all of it. If there is a carb the ECM has nothing to control but spark. All of the other sensors would be gone. Thinking a by pass for the spark control and just unplug the ECM. The reason for gettinbg rid of the A.I.R crap is just to make room and clean up the under hood area. Would love to see a step by step of this change over
Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
Not intimidated by it. Put my first engine together in 1971. A 454. did everything. but the shortblock. Cam, heads, intake, carb, headers. all of it. If there is a carb the ECM has nothing to control but spark. All of the other sensors would be gone. Thinking a by pass for the spark control and just unplug the ECM. The reason for gettinbg rid of the A.I.R crap is just to make room and clean up the under hood area. Would love to see a step by step of this change over
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
I did that to my 84 years ago. Having a factory service manual was invaluable. You need a vacuum HEI distributor, a low profile intake, carb and a lot of time. I didn't hack anything when I did the conversion and later moved on to a Superram and now a miniram.
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
It's actually a very easy swap.
Edelbrock Performer 2101 intake manifold fits under the hood with a drop base air cleaner assembly.
As stated you will need a pre-computer controlled HEI or a MSD distributor/ignition box. You will need to rewire the fuel pump relay to be hot when the key is on... Pretty simple to take a 12v switched wire out of the fuse box and replace the ECM hot wire to the pump relay. You will need a return style fuel pressure regulator spliced into the factory fuel lines..... The Mallory PN-29387 regulator works well. The factory fuel pump works fine as it only uses 13psi on the CFI and it's easily regulated down to 6.5psi for the carb. You will need a way to turn the cooling fan on, most people use a 12v switch wired in to the factory cooling fan relay.... Its been done many ways. Aftermarket temperature switch controllers, manual switches to activate the fan and fan hot whenever the key is on.
Will
Edelbrock Performer 2101 intake manifold fits under the hood with a drop base air cleaner assembly.
As stated you will need a pre-computer controlled HEI or a MSD distributor/ignition box. You will need to rewire the fuel pump relay to be hot when the key is on... Pretty simple to take a 12v switched wire out of the fuse box and replace the ECM hot wire to the pump relay. You will need a return style fuel pressure regulator spliced into the factory fuel lines..... The Mallory PN-29387 regulator works well. The factory fuel pump works fine as it only uses 13psi on the CFI and it's easily regulated down to 6.5psi for the carb. You will need a way to turn the cooling fan on, most people use a 12v switch wired in to the factory cooling fan relay.... Its been done many ways. Aftermarket temperature switch controllers, manual switches to activate the fan and fan hot whenever the key is on.
Will
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
383vette is right; get a mechanical HEI distributor, stick a carb on, figure out how to hook up the TV cable, then re-use all the gauge sensors to feed info your your gauge cluster.
Power the fuel pump like rklessdriver said, or through the oil pressure switch (or both).
You can make an FPR out of the original CFI FPR if you want to. I've done it on a carb'ed SBC into a square headlight, Wrangler. Or you could buy one from Summit/Jegs etc. Either way, return it to the car's stock return line.
Last edited by Tom400CFI; Jul 17, 2018 at 03:35 PM.
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