I did it!!! It was a royal PITA, but it is complete and running. I swapped my EFI 300 for an EFI 351. It runs great!! Pics will be in my gallery by the end of the week. As well as a complete list of what problems I had and what it cost.

 

Congratulations!! The feeling of accomplishment will remain long after the knuckles have healed (<g>). Looking forward to the pics and the war story...
Shilly

 

did the harness plug in ? did you have to change the ecm?

 

and the thread miner of the week goes to blaaaaa!!! and yes he did have to change the ecm when he did that v8 swap 9 years ago!!

 

Wow, this thread was brought up by the grave! Just curious why he changed from the 4.9 to the 5.8?
Speed would be different but I would rather have the fuel economy and longevity of the straight 6 over the v-8.

 

Because the fuel economy is nearly identical and the 300 doesn't even have enough power to get out of its own way. The 351's life span is just as adequate also.

 

will the engine harness plug in to the plug at the fire wall or do you have to change the entire harness?

 

- fuel economy - not identical at all. The 300 gets much better mileage.
- Ford made millions and millions of trucks and Broncos with the 300. Seems to me that if they didn't have enough power to get out of their own way they would have done something about it. You're entitled to your opinion but my F-150 was no slouch.
- 300's last longer than either the 302 or the 351. 7 main bearings vs. 5 for starters.

You need the harness for the 351w.

I don't think this swap makes a lot of sense unless your engine is dead, you need it back on the road cheap and now, and you just happen to have a 351w lying around.

 

im just wondering if that 351 engine harness will plug into my harness on the firewall

 

My 300 got about 15-16mpg with regular maintenance, tune ups, and a rering. A 351 would do about the same. How much better is "much better" anyways?
The 300 had a long production run, true. That doesn't negate the fact that it was a gutless, long lasting engine. If you have never driven anything with power, I'm sure it feels pretty peppy though. Ford didn't need to do any updates because they sold as is. If you want to do some towing, a 351 is a better choice.
With regular maintenance, the 300, 302, 351, and 460 all have a long life span.

This swap makes perfect sense if you want some extra power for a little money.

 

I agree 100% there Zx.....I'm doing the swap to a carbed 351w....After it gets a nice rebuild, etc....Just tired of no go after 50mph.....And I already have the engine, full ignition, exhaust, etc.....

 

Sounds like it'll be fun.

 

I used to get 18 -19 MPG with my F-150. It had 3.08 gears, a 5 speed, and a 300. I never heard of any 351-powered truck getting more than 15. In fact, my Bronco, which I kept extensive mileage records on, got about 13. It had a 351, E4OD, and 3.55 gears.

I guess everyone's entitled to their opinion but you're one of the few people who believe that a 300 is gutless.

The 300 lasts, on average, the longest of all four motors. I would put money on it.

I disagree again. You cannot tell the difference between a 300 and a 351 below 3500 RPMs, all else being equal. The power output is very close between the two.

Now if you want to add a few upgrades to a 351, sure, it will be a lot faster. But you can say that about any motor.

 

well i guess no one has an answer