302 to 351 motor swap
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8th Gear
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302 to 351 motor swap
So need some help. I have a 1994 f150 with a 302 with the 4R70W U type tranny in it and I’m planning on swapping motors, I have a 351 engine out of a 1990 f150 that I wanna drop in and have been reading some forums on this swap but i can’t find 100% answers. Wondering if i can use the same tranny, computer and driveshaft or if they need to be replaced. Everywhere i have read has said both yes and no. Any help would be great. Thanks
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Joined: Jun 2006
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From: Ottawa, Ontario
Yes it will bolt right in and work well, no other drivetrain changes necessary.
The list of necessary changes is short but important.
You need a different flexpate to go between the engine and trans, it will be 164 tooth with a 28oz imbalance specifically made for the AOD/351 combo used in a mid '80's Crown vic.
You CANNOT use any wiring that comes with the donor motor, use only that which is currently on the 5.0.
You will need to either modify the 5.8 distributor to use a remote TFI or buy a later 5.8 distributor and put a cast iron drive gear on it
The exhaust Y pipe has to be widened or replaced, if you have access to a mig welder it's easy enough to do just cut it where is runs under the motor and add 3/4-1"
The list of necessary changes is short but important.
You need a different flexpate to go between the engine and trans, it will be 164 tooth with a 28oz imbalance specifically made for the AOD/351 combo used in a mid '80's Crown vic.
You CANNOT use any wiring that comes with the donor motor, use only that which is currently on the 5.0.
You will need to either modify the 5.8 distributor to use a remote TFI or buy a later 5.8 distributor and put a cast iron drive gear on it
The exhaust Y pipe has to be widened or replaced, if you have access to a mig welder it's easy enough to do just cut it where is runs under the motor and add 3/4-1"
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8th Gear
Joined: Nov 2019
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ok so do I need a new computer or can I use the 302 computer to communicate with the tranny
Yes it will bolt right in and work well, no other drivetrain changes necessary.
The list of necessary changes is short but important.
You need a different flexpate to go between the engine and trans, it will be 164 tooth with a 28oz imbalance specifically made for the AOD/351 combo used in a mid '80's Crown vic.
You CANNOT use any wiring that comes with the donor motor, use only that which is currently on the 5.0.
You will need to either modify the 5.8 distributor to use a remote TFI or buy a later 5.8 distributor and put a cast iron drive gear on it
The exhaust Y pipe has to be widened or replaced, if you have access to a mig welder it's easy enough to do just cut it where is runs under the motor and add 3/4-1"
The list of necessary changes is short but important.
You need a different flexpate to go between the engine and trans, it will be 164 tooth with a 28oz imbalance specifically made for the AOD/351 combo used in a mid '80's Crown vic.
You CANNOT use any wiring that comes with the donor motor, use only that which is currently on the 5.0.
You will need to either modify the 5.8 distributor to use a remote TFI or buy a later 5.8 distributor and put a cast iron drive gear on it
The exhaust Y pipe has to be widened or replaced, if you have access to a mig welder it's easy enough to do just cut it where is runs under the motor and add 3/4-1"
Elder User
Joined: Dec 2016
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From: Mid Missouri
I've done this very swap on my rig. It runs on the stock 302 computer very well. See my sig for the mods I have.
I also want to emphasize what Paul stated above about using the correct flexplate. You must use one for a mid 80's Crown Vic 351w otherwise your transmission will be destroyed the instant you start the engine after the swap.
I also want to emphasize what Paul stated above about using the correct flexplate. You must use one for a mid 80's Crown Vic 351w otherwise your transmission will be destroyed the instant you start the engine after the swap.
Cross-Country
Joined: Sep 2018
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I've done this very swap on my rig. It runs on the stock 302 computer very well. See my sig for the mods I have.
I also want to emphasize what Paul stated above about using the correct flexplate. You must use one for a mid 80's Crown Vic 351w otherwise your transmission will be destroyed the instant you start the engine after the swap.
I also want to emphasize what Paul stated above about using the correct flexplate. You must use one for a mid 80's Crown Vic 351w otherwise your transmission will be destroyed the instant you start the engine after the swap.
Anything I will need to change or replace --exhaust manifold etc.?
Hotshot
Joined: Jun 2015
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The 351W is taller and wider than a 302 so that is why the 302 “y” pipe doesn’t bolt right up.
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8th Gear
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Trans control module
So I have a 1994 f150 the I pulled the 302 engine and swapped it in with a built 351 that is carb I have the 164 tooth flexplate and all that. The truck has the 4R70W U type tranny in it and was wondering what Transmission control module I should get. Because how it is sitting now the tranny won’t work from what I’m being told. Any help would be great thanks
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