Hi all. New to this side of the forums. I am usually over on the 53-56 side.
I am looking to buy a 84 f150 4x4 manual 4 speed with a 300i6 in the next day or so. I have read a bunch about the duraspark II & carb swap to get rid of the feedback system and think that will be one of the first things I do.

My question: I am a little nervous about the engine with 186,000 miles smokes a little when you first start it....but I know these go forever if maintained. the owner thought it may need a head gasket with water in oil but when he showed it to me I didn't see anything and it didn't seem to be running hot. Anyway...I am still thinking of buying it and rolling the dice. I am thinking of picking up a second 4.9 spare engine advertised in CL from a 1970 and maybe start rebuilding it slowly for a swap down the road if and when this one ever croaks. My question is do the engines measure up the same from these years (84 -70) and if it is an advisable engine year choice for something like this? Would the 70 bolt up to the existing trans? any other major differences or issues to consider? Thanks all in advance. I am sure I will have many more questions for you all once I actually have the truck.

 

65 - 83 are the preferable years to own. 83 and older heads are stud mounted rockers, while 84 to 86 are feedback with pedestal style rocker arms. 87 to 96 are EFI motors and have different heads (tapped for air rails to blow air into the exhaust ports, swirl type chamber, pedestal rockers).

You can swap heads on any 300 from 65 to 96. You can put any 240 head on any 300, but you'll get a .5 increase in compression because the combustion chambers on a 240 are smaller.

Also, 87 to 96 300's have no hole for a mechanical fuel pump, whereas 86 to 65 motors do.

ALL 300's have 7 main bearings, gear drive timing gears, forged rods, and cast pistons. Some 300's had a forged crank (usually found in F600's) and a heavy duty exhaust manifold. 300's also only came with a 1bbl carburetor. No 2 or 4bbls factory.

Water in the oil is due to condensation on short trips. It takes about 30 miles for the water to burn out of the oil completely.

Smoking on start-up can be the valve stem seals or just condensation. If it runs fine, doesn't use coolant (check your radiator fluid level regularly), doesn't burn oil, then I'd drive it till it quits.

The colors to look for in smoke are white, blue, and black. Black is a motor that's running too rich. Blue is burning oil. White is either condensation or coolant.

The 300 also uses the Windsor bolt pattern for the bellhousing. 240, 255, 289, 300, 302, and 351 Windsor and Cleveland interchange.

 

I'd look over the 1970 engine carefully.

The 240 is the sister engine to the 300.

A lot of people call their 240-I6s, 300-I6s at selling time.

Same problem happens to the 360FEs, they magically turn into 390s at time of sale.

Other than that, you shouldn't have too much of a problem, most parts swap from one to the other without any problem as stated by 1983F1503004x4 above.

 

Bingo. And, the only real way to find out if it's a 240 or a 300, is to PULL IT APART. They're identical on the outside. You might be able to find a number on the block or on an old valve cover sticker to identify it, but other than looking at the vin #, the stroke has to be measured.

300's have a 3.98'' stroke, with a shorter rod than the 240.

The 240 has a 3.18'' stroke, with a longer rod.

If I remember right, a 240 also has 68CC heads, whereas the 300's have 76CC heads.

The 240 was also the standard engine up until about 74 or 76 (can't remember). The 300 was the optional upgrade, beyond that you could get a V8. But, 240's were standard.

 

great info guys, thanks. Turned out the engine was a 240 after all by looking at a metal tag on the engine. Good call on that one.

 

Related (sort of) question: I have heard that there are differences in the crankshafts, such that you could only use the 5-speeds with the later engines, and that the 5-speeds cannot be used with the older engines. Any truth here?

 

No truth at all.

You can use any 300 or 240 with any automatic or manual transmission that went behind a 240, 255, 289, 300, 302, 351 Windsor, and 351 Cleveland.

This includes, but is not limited to, a C4, C5, C6, FMX, Automatic OverDrive (AOD), E4OD, AOD-E, New Process 435, T-18, T-19, ZF5, Mazda M5OD, SROD, the Ford 3-speed, etc.

If you're using a manual, it has to have the bellhousing with the Windsor bolt pattern, or the transmission has to have an integrated bellhousing (like an M5OD or ZF5) with the Windsor bolt pattern. For automatics, anything that went behind any of the above motors will work.

You just have to make sure you're using a 300 flywheel for manuals, and a 300 flexplate for automatics. Do not put a V8 flywheel or flexplate on a 300. The 300 uses a zero balance flywheel.

 

It's a pretty popular upgrade to swap the 5-speed with the older trucks. Thinking of doing it myself when my old T-18 gives up.


Now there is a difference between hydrallic and manual linkage clutches between certain years but that can also be delt with.

 

what about the main bearing caps? After getting getting my 1986 ford 300 six cylinder block back, I was missing the very front and the #4 main caps. The ones that have *sides* on the bearings. I bought a used set off a 1987 300 six. The front fit but ghe other tabbed was the #5 cap. Tried it but when I torqued it, the crank won't turn. Just wondering what the difference was if any. Ty

 

You must have the cap resized to work on that block with that crank.

 

Ty for the reply

 

Not sure of years but some have oil dipstick in different location as oil pan deep part is different.

 

That's why when rebuilding a engine you always keep the caps in order and put them back on exactly the way they came off. The crank saddles on the block are machined with the caps bolted in the block. A machine shop should be able to get you going, if you can find one. It's getting harder and harder to find a machine shop and when you do, they are backed up for months.

 

Ty Franklin. Mistake #1, I took the caps with the block and crank to the machine shop. Mistake #2, I didn't make sure I gad them all in the box when I picked it up from the shop. It's been 3 months since I picked them up, but I'm hoping they still have them. Finding replacements has been impossible

 

The one cap from the 87 "that fit", you need to plastigage it to see what the clearances are. It may be too loose. I would be surprised if it had the correct clearance. If they can't find the original caps, you will have to get the new ones you have machined. If you can prove they lost the caps, then possibly they would give you a break on the machine work to redo the main caps with the new ones installed.