Differential
390 engine to 302 engine
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Junior User
Joined: Nov 2007
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From: PEARSALL,TX
390 engine to 302 engine
my dad is wanting to change engine from a 390 to a 302 is this possible with out putting a big hole in the pocket found engine already but what else will be need to modify to make it work by the way its a 1974 F-100 pickup
Senior User
Joined: Jan 2004
Posts: 388
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From: Northern Indiana
Stick or auto? You can just change the bellhousing on a stick, auto you will need a different tranny. Motor mounts are different, but not an expensive problem. All the brackets are also different, what all do you get with your 302?
I bet his reason lies somewhere in your user name ''ford390gashog''.
I love FE's, but they love gas!
I bet his reason lies somewhere in your user name ''ford390gashog''.
I love FE's, but they love gas!
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Junior User
Joined: Nov 2007
Posts: 93
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From: PEARSALL,TX
Stick or auto? You can just change the bellhousing on a stick, auto you will need a different tranny. Motor mounts are different, but not an expensive problem. All the brackets are also different, what all do you get with your 302?
I bet his reason lies somewhere in your user name ''ford390gashog''.
I love FE's, but they love gas!
I bet his reason lies somewhere in your user name ''ford390gashog''.
I love FE's, but they love gas!
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All the expense in swapping crap over will buy several tanks of gas. Why bother for maybe 1/2-1 MPG improvement?
Not to mention the power will be halved.
I would consider swapping the 3rd member (around $50-75 from JY) to a 3.25, 3.00 or even a 2.75 if mileage is really that much of a concern.
Josh
Not to mention the power will be halved.
I would consider swapping the 3rd member (around $50-75 from JY) to a 3.25, 3.00 or even a 2.75 if mileage is really that much of a concern.
Josh
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Also consider you may need a different intermmediate driveshaft.
Josh
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Junior User
Joined: Nov 2007
Posts: 93
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From: PEARSALL,TX
All the expense in swapping crap over will buy several tanks of gas. Why bother for maybe 1/2-1 MPG improvement?
Not to mention the power will be halved.
I would consider swapping the 3rd member (around $50-75 from JY) to a 3.25, 3.00 or even a 2.75 if mileage is really that much of a concern.
Josh
Not to mention the power will be halved.
I would consider swapping the 3rd member (around $50-75 from JY) to a 3.25, 3.00 or even a 2.75 if mileage is really that much of a concern.
Josh
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For a Ford 9 inch, the center-section is removeable has several "nicknames"...
3rd member
Drop-Out
Center-Section
Pumpkin
They can be had fairly cheap in most junkyards and just requires pulling the axles and disconnecting the driveshaft. Some silicone and new gear oil and you're good to go.
Not sure what you are running now, but if you have a 4.11 to 3.50 rear ratio, going to a 2.75-3.00 can make a good sized difference in fuel economy.
Josh
3rd member
Drop-Out
Center-Section
Pumpkin
They can be had fairly cheap in most junkyards and just requires pulling the axles and disconnecting the driveshaft. Some silicone and new gear oil and you're good to go.
Not sure what you are running now, but if you have a 4.11 to 3.50 rear ratio, going to a 2.75-3.00 can make a good sized difference in fuel economy.
Josh
Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
If you are looking to do it w/o spending much, then I would nix the idea. I've been that route. But I went from a 390 to a hp 300. Everything is different, from rad. hookups to throttle linkage, and ten things you didn't think of. Each means $.
I wanted to keep the 390 horse power, but gain 50% better mileage. I actually ended up doubling my mileage with the same towing/hauling ability--but it was not cheap. It is much cheaper to gain hp out of a v8 than an inline six. However, the 300 (4.9) produces peak hp at a much lower rpm than a v8.
Good luck.
I wanted to keep the 390 horse power, but gain 50% better mileage. I actually ended up doubling my mileage with the same towing/hauling ability--but it was not cheap. It is much cheaper to gain hp out of a v8 than an inline six. However, the 300 (4.9) produces peak hp at a much lower rpm than a v8.
Good luck.
Tuned
Joined: Dec 2008
Posts: 269
Likes: 1
From: Paradise, CA
I agree.....gear swap not an engine swap. Also with all the money you save, get rid of the points and run a good electronic ignition, coil, wires, plugs, etc. Also get a modern cam, a modern intake, a small 4 barrel carb, shorty headers with a good exhaust. You'll spend 1/4 the money, get better mileage, and it will perform much better. My papa always said, "son, there's no replacement for displacement."
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