Hi, I'm looking to switch out the 300 ci inline 6 in my 65 f100 for a fresher motor and was wondering if anyone knows what years should I be looking for that will basically drop in with very few mods.

Any info will be greatly appreciated.

 

Staying with the inline six? If so get a fuel injected model. Or are you looking to go to a v8?

 

Ask on the inline six forum further down.

 

Hi, thanks for the reply.. staying with the inline six..Will I be able to change the serpentine belt harmonic balancer to a v belt style if I go with a FI engine? Everything else looks the same. I plan on using FI exhaust manifolds and an Offenhauser w/ Holley intake system.

 

The inline 300 was produced from 1965 through 1996. In 1987, the 300 was fuel injected (4.9L). '87-'96 had a serpentine belt drive setup. '87-'96 4.9L blocks also don't have a hole in the side of the block for a mechanical fuel pump.

Pre-'87 model 300s don't have a threaded hole in the forward, left side of the head for one of the serpentine bracket attachment bolts.

 

Why not just do a rebuild? Nothing super hard about it, then you'll know what you have also, add some Heddman dual outlet headers an offy intake and a 390cfm 4bbl, I've done that 3x now on different trucks, got 18mpg driving my 79 F250 4x4, 4.10's and 33's all the way to Missouri when I sold it to my BIL. Unless there is something wrong with block, which I doubt, you should only be into rebuild + headers, intake, carb for appx $1000 + the satisfaction of doing it yourself

 

Back in February, the #5 piston separated from the connecting rod in the 240 in my '69 F100, while on my way home from work. It gouged a big hole in the #5 cylinder wall and punched a hole out through the left side of the block --wasn't any possibility of saving that block.

I found a 300 (minus the head) in the wrecking yard that had been in a '65 F500. I got it, brought it back to the shop, tore it down, took the block/crank and my 240 head to the machine shop to be hot tanked and the machine work done on the block, crank and head. When they were done, I brought the parts back to the shop and assembled the engine.

The 300 after I got it from the wrecking yard.





Back from the machine shop.














The 300 is much stronger than the old, tired and worn out 240 it replaced. I also upgraded to a much larger radiator, a Duraspark II electronic ignition (no more points), a set of '87-'94 4.9L EFI exhaust manifolds and true dual exhaust during this engine swap.

 

Thanks guys, I'm going to look for a pre 87' engine then. I'd love to rebuild but this truck needs so much work that a rebuild might put me over the edge mentally. The head on the current motor is rebuilt but the block is junk because of a rusty cylinder. Maybe I'll just drop the head on a decent block and hope for the best.

 

Unless you can find/get a short block that's rebuilt (receipts/paperwork to prove it), getting an engine of unknown condition from some random individual or from a wrecking yard donor may not be in any better shape than what you already have.

I presume this isn't your daily driver (although my truck is my daily driver). Since you already have the engine on hand, it wouldn't hurt to take it to a machine shop and have it checked out to see if it's rebuildable. If so, you don't have to spend time and money chasing down another engine. If it turns out that it's beyond being rebuilt, well, then you could look for a replacement.

I only changed engines because my 240 blew up and the block wasn't salvageable. Since I wasn't going to be able to reuse the block, it only made since for me to step up from a 240 to a 300.

 

Might be worth your time to talk to a local engine shop. When i disassembled my 240 to replace gaskets I found that it had a lot of issues. Block needed to be bored, bad cam, etc. A machine shop near me quoted $1700 for a complete rebuild. That included all machine work to block and head, new pistons, rings, all new valves and new valve seats and rocker studs, new cam and lifters, oil pump, all gaskets and seals, rod/main bearings, etc. Basically a brand new engine. If your head is good, and if your block doesn't need to be bored, it would be a pretty cheap rebuild. Just cleaning it up and re-ringing it would make it a new engine. You won't have to go through it again that way. You never know with old junkyard stuff. My 240 ran good. I was shocked at how much stuff in it was soooooo bad. The cam had badly worn lobes and 3 cracked pistons skirts, nasty ridge in the cylinders,etc. You never know what you will find even in a good running engine.