Hello, new member here. Recently picked up an 86 F250 with a 351 and 4 speed manual for a great price due to the engine being shot (coolant filled oil pan, rusty 4 bbl intake manifold, etc) but has a nice rust free frame and body and the interior is very clean. I can rotate the engine by hand and starter but it's coming out to be rebuilt in the future as time and finances allow. I have some questions about an engine swap project that I know will irritate some but I'm not looking to tow or race the truck, just want to drive it. I have a relatively low mileage 302 from a 94 F150 that will be going in so yes i know I will be losing some torque and power, but it's what I have and will be working with on this project. Couple questions right off the bat: I believe the flywheel will mount up to the 302 crank without issue but want to confirm, as well as starter compatibility. I will be putting a carb on the engine instead of the fuel injection unless I can somehow figure out splicing in the harness and computer (which I have along with all the wiring harnesses but would rather not unless someone can talk me into it and through it). The 302 is complete and I believe I need to use the installed 302 dizzy but not sure if that will work without the computer wired in so that's a concern. Are the motor mounts going to be same to where I can pull the 302 and drop it straight into the F250 frame? I'll be using the alternator from the 302 as well so any wiring advice on that will be welcome. I'm decent with problem solving this stuff and have a manual that covers 1980 through 1995 so should have the basic wiring diagrams anyway, but covet your advice and lessons learned from past experience. The physical engine swap should be straight forward and not much of a hassle, I'm mainly looking for advice on the electronics such as the distributor and alternator wiring. And what intake manifold have you 302 guys had good success with? The carb is a new Holley 1850. You don't have to tell me I'm an idiot for going to a smaller displacement engine. Haha. Thanks in advance.

 

You could use a newer style (aftermarket) HEI Coil over cap. It would be self contained, not needed a computer, and only single power wire connection

Regarding the alternator, I believe a 1994 would be a G3 alternator, but nut sure. 1986 could be a G2. Point is we would need to know more before giving advice.
Post some photos of the alternators, front and back views.
Jim

 

As Jim mentioned, you will need a new distributor for the 302. The original 302 distributor needs the computer system to run. That is a bunch of wiring hassle and modifying the 86 fuel system that would be a lot of work. The HEI aftermarket unit he mentioned would be the simplest to wire in.

You can't use the 351w flywheel on the 302. The 351w is 28 oz inbalance, the later 302 is 50 oz inbalance. When you get the new flywheel check the diameter to the 351w, the 351w starter may work with the 302 flywheel you buy.

You might as well use all the accessories that come with the later 302 if you have them. It more than likely has a serpentine belt, while the 351w had a v-belt system. You need to use ALL the later 302 accessories including the fan. If you start mixing and matching older v-belt 351w stuff with the newer 302 serpentine stuff, be very careful doing this. Once you get everything mounted and in place, we can then figure out the newer alternator wiring to the older truck harness.

Hopefully you have the 302 truck exhaust manifolds. While the 351w exhaust manifolds will bolt to the 302,, they are different angles on the outlets, since the 351w is a wider engine. You will need the 302 exhaust manifolds and a 302 y-pipe.

You will also need to add a low pressure electric fuel pump on the 86 to feed the carb you swap onto the 302. The later 302 has no provisions for a mechanical fuel pump.

 

You will need a correct 302 flywheel.......351w & early 302 engines had a 28oz inbalance, but around 1981 302s changed to a 50oz inbalance.

 

Thanks for the words of advice. I figured an aftermarket distributor would be the way to go. Thank you for confirming. As far as accessories, yes I plan on using everything from the 302 with the serpentine setup, and I will take and post pictures of the alternators tomorrow when its light out. The 302 has a smaller alt and AC compressor which I plan to use. I believe I have the y-pipe still mounted up to the exhaust manifolds (didn't look to closely at that but did notice they were cut off right after the O2 sensor and small connecting/balancing pipe (wrong term?). figured a low pressure fuel pump for the carb which should be straightforward. I wasn't thinking the flywheel would be an issue but sounds like it will. Does that mean I will need another clutch setup as well of will the current pressure plate still work? I'll put a new clutch disk in while it's apart but was hoping the rest would work. I'm still tempted to wire up the computer and a high pressure fuel pump but want to get the other engine out first and see how I'm feeling.

 

Some clutch plates are 10" diameter, some are 11". Likewise, some flywheels are drilled for 10" pressure plates, some for 11", & some will take both.

​When you determine what diameter clutch you will be using, you can get a matching flywheel (not forgetting the 50oz inbalance).
​​​​​

 

Keep your fingers crossed, most aftermarket flywheels for trucks are drilled for both sizes of clutches. Your 351w clutch should work once you get the flywheel for the engine.

Unless you have a shop near you that will make and weld up some pipes, sounds like you need a new y-pipe. You can get a early 80's one that did not have O2 sensors and no cat. Most of the later ones came with a cat made into it and they are pretty much a can't get item. If you need a cat to pass inspection, you can get the early y-pipe with no cat, and then get a universal clamp on cat and put that in after the y-pipe.

 

No inspection will be necessary where I’m at. I’ll have to take a closer look at the y-pipe Tuesday after work. I think I can weld something up the way it sits. It’s all I can do not to be out working on stuff today but being Mother’s Day I’m locked down. Haha.

Anyone know about the motor mount compatibility between the two engines?

 

Will bolt right in. The 302 and the 351w have the same motor mount configuration and the same bellhousing pattern.

Same cylinder heads, but the 351w uses larger head bolts. Timing covers the same. 351w block is taller so the intake is wider than the 302. 351w has larger main bearings, so things on the bottom end are a little different.

 

Engine is out. Definitely easier than the 5.4 I swapped in my 2010 Ford F150. Got it on the stand and started pulling it apart and it was pretty greedy on the inside. I’ll rebuild it eventually but for now it’s gonna be the 302. I ordered the correct flywheel today. Tomorrow gonna pull the engine from the donor and start getting it prepped to go in. Going back and forth between try to keep it injected or not but pretty sure I’m gonna carb it. Pretty sure the original starter will be used correct? Since it bolts to the bell housing and flywheel size will be the same (164 tooth). Biggest challenge will be exhaust I think. I’ll try to post more pictures do you can see what I’m dealing with.

 

Here’s the exhaust situation. I think adding onto these will be doable but if I had a two into one adapter that would be best. Guess we’ll see just how good my welding is.

 

I believe the newer starter is a PMGR style. Does it look different.
If it is a PMGR starter you have to wire it differently.

https://www.ford-trucks.com/forums/1...l#post21223862

See post 15 for link to wiring info.
Jim

 

New starter is different. I believe it has the solenoid attached as opposed to on the inner fender wall. Not sure if they are physically the same size/shape or not but I was thinking the original should fit since the bell housing and shield/cover is the original still. I’m not home to look but am I missing something?

 

Sorry, I just reread your post. You want to use the old style 1986 starter. Your choice.
Personally I would use the newer style PMGR starter, which is what I assumed you also wanted. The PMGR is a better starter in my opinion, but Google it and then decide.
I upgraded my 1986 to the newer style PMGR starter and kept the old one behind the seat, with my ride along spare parts.
Just note the difference in wiring it, if you use the newer PMGR starter.
Jim

 

Here's a y-pipe.