Howdy, long time lurker. I have a 65 F100 Step Side , Short Bed. Picked up a donnor 91 F150 with 4.9, 5 spd, complete, runs and drives great.
Looking for advice on the EFI part of the swap. Also, I don't expect motor mounts to be an isue, but it's been a long time since any engine swaps for this old man. All advice appreciated. I tried to find help but my searchs came up short. Thanks.

 

Are you keeping the EFI? Not sure on the 91,, I know you will need most of the wiring,,, I don't think they were using Throttle Position Sensors yet,, just O2 sensor and a few others,, I am pretty sure the 91 is a hydraulic clutch,,?,, so you will need to be creative with that,, but I helped do similar before,, not to bad,,, keep an open mind. And as with all swaps,, new clutch/rear main before it goes in,, saves time later,,,
Good Luck!
Joe

 

The 91 4.9 is a fully integrated EFI system and uses all the sensor's found today including the HEGO, TPS, MAP, ACT, EEC power relay, Fuel pump relay, EGR, VSS (this in the rear axle) I am not sure one can use the earlier to 89 AOD/C6/Manual Pulse unit as they went to electronic transmissions and speedometers in 90. All these will need to be reused including the emissions solenoids evap selonoid and cansiter with vapor return tot he fuel tank. These trip The MIL if these are not hooked up and reading within spec.


The 91 harness is very difficult to pare apart and use piece meal. It has a crap load of extra things going on. Can you do it? Sure with enough patience and a manual. Haynes Manual for 80 to 96 has the wiring diagrams. you just need to weed out all the chaff.

I would recommend you install the entire harness in your truck as it will surprise you that most of the 91 harness will plug and play from the headlights to taillights. I did this on my 64 i built and will be using a 87 to 89 harness on the 69 Crew Cab to use the 88 472 EFI big block.

For the trans it will have a hydraulic clutch,with the throw out bearing being the slave cylinder Internal on the input pilot if it is an M5OD. It may not also have the output for a speedometer cable. A clutch master can be adapted to the firewall and the clutch arm modified to push out to actuate. Or a remote master under the floor actuated by the stock linkage.

I would not recommend converting a 4.6 EFI engine to Carb. The heads were redesigned for the EFI and loooong runners and do not like the short one on a carb intake, It Kills them .

Garbz

 

Says the one who knows!! Good info Garbz!

 

My daily driver is a '91 F150 with EFI 4.9L and 5-speed.
Mine still has a cable driven speedometer (not electronic), and the VSS is not in the rear end... it is on the transmission end of the speedometer cable. You can ditch the air pump and air rail if you also ditch the catalytic converters and run a shorter belt. If you leave all of the smog vacuum relays hooked up and just cap off their vacuum nipples they still think they're activating the smog equipment and you won't get any check engine codes.

 

Running one of these swaps in my 78 for years now, very straight forward. Only real isue I had was using the stock trans clutch linkage. I had to custom machine a new pivot ball to thread into the engine. The newer engine had the boss in the block but it wasn't threaded and the hole was bigger than the stock pivot ball. I used a 87' truck van harness. If you use a stock trans the VSS on the older trucks works with the old transmissions. Just make sure you get the cable and everything.