Hey folks.I own a 1986 ford f250 4x4.It has the original 300 six/4 speed trans/np208 tranfer..Engine has served me well with few problems but it`s getting tired and time to replace it.Im wanting to replace it with a small block.Was thinking a 302 from about the same year or little older truck.Just wondering what kind of problems im gonna run into.Parts i would need,Etc!!Thanks in advance guys!!!

 

Don't do it. Stick with the 300 six or put a 351w in it. If you put a v8 in it, you will have to take the six cylinder frame perches off your frame, and put v8 perches from another truck in their place. A 302 or 351w will then bolt in place. There will be a few odds and ends after that need to be swapped out.

 

Id go 351w for the low end torque

 

I would go with a 351W for sure.

 

When I had my 1977 f100 I did the thing your thinking about doing. Here is my opinion and input on it..

I took out my 300 and replaced it with a 302, yes the 302 is a good motot but if you intend to use the truck as a truck and not just a daily driver I would suggest rebuilding that 300. The 300 is a work horse, no one dislikes a 300, its the best motor FORD built! The 302 is only 2 cubic inches bigger but the 300 will outlast and outpull anything with that 302.

302= More power, speed, less pulling power, high end torque
300= Great pulling power, low end torque

KEEP THE 300!

 

Im planning on using this truck for competing in mud slings at the local fairs coming up soon and climbing sandhills with a few friends.I have already purchased a 205 gear to gear transfer case to replace the np208 chain drivin.I have purchased 4:10 gears and installed them front and rear.I also put a new set of 36/12.50/16 boogers on the truck.The 4 speed is gonna stay in the truck because i just like the 4 speed.My concern is the engine.I don`t think the 300 will give me the performance i am gonna need. Even with a rebuild..I noticed a few folks recomending the 351.I know i will have to change the perchs and prob motor mounts as well.If i go with a 351(Won`t i need the flywheel/bellhousing/Etc from a 351 truck)?I am gonna pull the whole engine/trans/transfer all at the same time.This truck is not gonna be daily drivin anymore.I have a 2006 f250 that i drive daily now..The 300 is also needing a rebuild after giving me 246000 miles of problem free driving.Thanks to all for helping me in this matter(And i do agree the 300 cannot be beat for a good all around engine)If you think the 300 will perform better than a 351 then i would just as well keep it,I just don`t know if it will

 

The 351w will bolt right up to the bellhousing. You will have to get a flywheel for the 351w, but I am guessing after you do that, the 300 six clutch will bolt right up to that.

The 351w is the largest engine that's going to bolt right in, and I think is what you are going to want for that use, unless you want to change the bellhousing too and install a 429 or 460.

 

Thanks for the help Franklin2.I have located a 30 over 351 recently rebuilt in a 1982 ford f150.The guy is wanting 600 for the engine.I think i can`t go wrong with it considering he is gonna give me all paper work and reciepts from the shop that did the rebuild.Do you think that the 351 will bolt right up to my bellhousing/Of course when i get the flywheel?It has the three hundred six bellhousing on it.The guy with the engine for sale told me that he thinks i will have to change the bellhousing to the 351 for it to work!!!!

 

Yes the transmission will bolt up to that bellhousing.

 

Ok thanks alot Redneck1465,I am gonna buy the engine and hopefully find a flywheel for it,I will keep you guys posted on what i run into!!!!Thanks a lot to everyone who has givin me advice

 

I see advance auto keeps the flywheel in stock at the store for about $81.00.

 

Ok,Thx for the info there Franklin2.Problem is my town i live in doesn`t have an advance auto.We have an autozone and a car quest and thats it!!Im sure one of them will have the flywheel in stock,Can you think of anything else i will need where i can have it here when i get ready to do this pull.Im gonna be doing it myself in behind my house with a cherry picker.Thinking of doing it this weekend coming up with weather permiting.Hopefully start on it sat morning and have all of it done and running by sunday evening.Also what headers would you recomend that i run!!!!

 

That's going to be a tall order to have it running by Sunday. You will definitely get it in there, probably Saturday, and if you had a v8 truck there to steal parts from, then Sunday would be doable for it to be ready to go. But you will probably run into some little stuff that will not fit correctly, and may hold the operation up. I seem to remember the radiator may be different. But I can't remember exactly, so if you go to Autozone's website, you can look your truck up with a six, and then a 351w, and see if the radiator is a different part number or the same. Someone else may know all the little things you might run into(throttle cable comes to mind too).

As far as headers, buy the best ones you can afford. I bought cheap flowtechs when I had a 351w, and they fit ok around the engine and the engine compartment, but they came out and hit the auto transmission pan on one side, and the tranny crossmember on the other, so I had to do some bending to make them work. They are pretty thin too.

 

The 351w would be better than the 302. I would stick with the tough 300

 

I think he said he wants to sling mud, not pull a wagon load of hay around at 5 mph.

If he is leaving all the engines bone stock, sure, I wouldn't recommend a 302 for pulling extreme loads in an F-250... but if this is being built for competition, the 302 is a better choice than the 300. Dollar for dollar, the 302 is going to make more power. It does in stock vs stock, too, but we won't go into that.