69 F100 engine swap
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2nd Gear
Joined: May 2022
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69 F100 engine swap
HI all, first time posting here, so be gentle,please! I have a '69 F100 with about 84k miles on a (mostly) original 240 CID I6 with a 3 on the tree tranny. Only real mods so far are the addition of power steering and brakes. The truck tops out around 70 mph, which has been fine for crusing around locally, but I'd like to make some simple upgrades to safely get the truck moving fast enough to keep up with normal highway traffic (80-90 mph). To do so, I'm thinking I'll have to do an engine swap, but since I'm not looking to race it, I'm hoping to drop something in that's pretty tunrkey so I can keep the existing tranny and some money in my pocket. Any suggestions on engine options and / or other mods to consider to get it moving 15-20 mph faster at the top end?
Last edited by Jawny Cash; Jan 30, 2023 at 10:46 AM.
Tuned
Joined: May 2015
Posts: 413
Likes: 52
Are you running out of gear or motor? If your concern is engine RPM you may be able to go to a numerically lower rear gear ratio to give you some more MPH. If you are running out of motor HP there are several great 300 in-line 6 threads on this site on what is involved in a 240 to 300 swap. Any V8 swap will involve mounts or mount relocation, potential clutch or transmission swaps or mods, throttle linkage, etc. The 240 to 300 swap is likely the most logical move. Look for some threads from Ultraranger and there is a nice thread on an industrial 6 cylinder swap. With the added HP and torque of the 300 6 cylinder you may still want to look into a rear gear swap for better high speed highway manners.
Cargo Master
Joined: Feb 2006
Posts: 3,009
Likes: 250
From: North Pole, Alaska
Remember, the Big Sixes (240/300) use a Small Block Ford bell housing pattern.
There are 3 V-8 engine families that are useable, but there are tradeoffs due to radiators, engine stands or perches, engine mounts, and bell housing patterns etc:
SBF (302/351W/351C can use 69-79 F-100 302/75-79 351M/400 engines stands-302/351W/351C use SBF bell housings)
FE (352/360/390 use 67-79 Big Six/ 67-76 FE engine stands-but use FE pattern bell housings)
335 series (351M/400 use 75-79 engine stands-but use a 385 series (429/460) bell housing pattern)
There are 3 V-8 engine families that are useable, but there are tradeoffs due to radiators, engine stands or perches, engine mounts, and bell housing patterns etc:
SBF (302/351W/351C can use 69-79 F-100 302/75-79 351M/400 engines stands-302/351W/351C use SBF bell housings)
FE (352/360/390 use 67-79 Big Six/ 67-76 FE engine stands-but use FE pattern bell housings)
335 series (351M/400 use 75-79 engine stands-but use a 385 series (429/460) bell housing pattern)
Cargo Master
Joined: Jul 2015
Posts: 2,067
Likes: 138
From: tucson
What is your current rear end ratio. I went from 3.50 to 3.00 in my '66 with a 240 and 3 on the tree. It can be a real dog getting started on any kind of incline. My mpg actually went down, when I swapped to the 3.00. I spend more time at higher rpms, in second gear, than when I had the 3.50 rear end. It is much nicer above 40mph but the engine power is lacking at highway speeds. What tires are you using? I have a mildly built 300 that will be going in soon.
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