Swapping to a bigger engine
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Cross-Country
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Swapping to a bigger engine
Hello,
this is more of a hypothetical but I’m curious none the less. I have a 1988 f250 with a 5.0 302 that has around 140k miles. I drive this truck very seldom so it will likely never be driven more than 500 miles in a year. Saying that, this truck has tremendous sentimental value to me and so I will probably pay for any repairs it needs to continue driving as long as I am living. With that said, in the event that the engine ever goes out, how hard is it to swap to a 351? And just for giggles, a 7.3? Are we talking much more complicated and much more expensive? Or minor additional changes outside of just swapping the motor out and hooking things back up?
this is more of a hypothetical but I’m curious none the less. I have a 1988 f250 with a 5.0 302 that has around 140k miles. I drive this truck very seldom so it will likely never be driven more than 500 miles in a year. Saying that, this truck has tremendous sentimental value to me and so I will probably pay for any repairs it needs to continue driving as long as I am living. With that said, in the event that the engine ever goes out, how hard is it to swap to a 351? And just for giggles, a 7.3? Are we talking much more complicated and much more expensive? Or minor additional changes outside of just swapping the motor out and hooking things back up?
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
A 5.8 is a relatively easy swap as it's in the same engine family as the 5.0 so nothing but the engine has to change, but a 7.3l diesel swap is much more complicated as both engine and trans must be replaced as well as the whole fuel system and some electrical.
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Cross-Country
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Perfect, thank you for this reply, exactly what I was looking for! I assumed the 7.3 would be much more complicated, but glad to hear that the 351 isn't much different than just replacing with another 302.
Lead Driver
Joined: Feb 2002
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From: Greater Austin, Texas
I put a 460 in my 91 F150 in place of the original 300 Six. I also put a 7.3L IDI into a 91 Bronco. The 460 is easier than the 7.3, but harder than the 351. IMO the 351 does not offer enough extra grunt to be worth the trouble and it'll get the same MPG as the 460.
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Cross-Country
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Given that the few times I use my truck it is almost always for hauling and towing, do you believe that the swap to the 460 would be worth the added trouble? From what I can tell, your post seems to read that there isn't a significant difference from the 302 to the 351 to warrant going through any trouble to make that swap happen. I couldn't care less about gas mileage to be completely honest, I fill this truck up once every few months so it isn't really a big deal.
Fleet Mechanic
Joined: Jul 2019
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Since you have a light duty version F250, just stick with a 351. I guess you can always dress that up with a 392 stroker or something of the sort, but you don’t have to fart with whole driveline swaps at least.
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Cross-Country
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It's light duty in the sense that this one has a 5.0 when the default for the f250 XLT lariat was a 5.8? Or did ordering this truck in the 5.0 inherently change some of the other components of the truck? Hadn't looked into the 392 much, thanks for the suggestion.
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Laughing Gas
Joined: Oct 2003
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From: Lynden, WA
Reference to "light duty" is the truck you have probably has a semi floating rear axle while "heavy duty has the full floating rear axle. Installing a 351 will give you more towing power but swapping to a 460 will be a much larger increase in towing power. The big problem will be the transmission. Swapping to a 351 will permit you to use the 302 trans and a 460 swap will require a new trans that fits the 460 bolt pattern. A 302 trans behind the 351 will probably require a rebuild due to the 302 being somewhat "weaker" then a 351 built transmission. I owned an 87 F250 4WD with a stock 460 and 4.10 axles. Was a very strong "tow truck" for 8-10k loads but never saw gas mileage exceed 11mpg. I later owned a 89 F250 2WD with a 302 auto trans and 3.54 axle. It was almost worthless for towing anything heavier then 2-3k loads.
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Cross-Country
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Reference to "light duty" is the truck you have probably has a semi floating rear axle while "heavy duty has the full floating rear axle. Installing a 351 will give you more towing power but swapping to a 460 will be a much larger increase in towing power. The big problem will be the transmission. Swapping to a 351 will permit you to use the 302 trans and a 460 swap will require a new trans that fits the 460 bolt pattern. A 302 trans behind the 351 will probably require a rebuild due to the 302 being somewhat "weaker" then a 351 built transmission. I owned an 87 F250 4WD with a stock 460 and 4.10 axles. Was a very strong "tow truck" for 8-10k loads but never saw gas mileage exceed 11mpg. I later owned a 89 F250 2WD with a 302 auto trans and 3.54 axle. It was almost worthless for towing anything heavier then 2-3k loads.
Mountain Pass
Joined: Oct 2020
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Having just done the 5.0 to 5.8 swap myself, its not bad and is fairly easy. It mainly comes down to what your intended use is. A 351w will have more towing/hauling capacity than the 5.0, but the 460 and 7.3 would increase that further. The gotcha is the rest of the suspension and driveline as generally the 351/460/7.3 have had different axles and suspension setups than the 5.0 and may be the first failure point.
Our use case is occasional towing/hauling so the 351w is a good move for us. If we were going to do more heavy towing/hauling, I'd be looking at a F350 whether OBS or newer, over just a 351w swapped F150.
Our use case is occasional towing/hauling so the 351w is a good move for us. If we were going to do more heavy towing/hauling, I'd be looking at a F350 whether OBS or newer, over just a 351w swapped F150.
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Cross-Country
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Great response! While I do tow a fair bit with the truck when I do use it, it would almost never be more than 3-4k and would only be about 10-15 miles with considerable hills and valleys. Anything more than that I usually call a friend with a bigger rig. Is that enough weight to justify the upgrade to the 351 or is the 302 adequate for that type of use a few times a year? I should note that i've done it in my current 302 a few times and the hills are pretty tough.