351 Upgrade
 

I have an '86 F-150 longbed 4x4, 302, 4 spd. I recently found a 351 H.O. from an '85 Bronco for $400.00. I want to pull the underpowered 302 out and install the 351w. I know I'll need to take the ign control module from the Bronco, but what else do I need to get? The 302 is fuel injected, and the 351w is carbureted, what other mods do I need to do?? Can I run just the Low pressure in tank pumps, and eliminate the High pressure frame mount fuel pump, or do I need to do something else all together?

The 351 will only be a little better. Bolt ons are your friend. You can practically sneeze on these motors and they will make power.

Basically, headers, intake, cam, and carb. If your feeling gutsy, heads.

You'll need to run a mechanical pump for the carbed 351W and either remove or disable the in tank electric pumps as well. Quite a bit of stuff like that will need to be changed around.

You shouldn't have to remove the in tank sending units when using a carb. Wouldn't you just need a/several accelerator pumps? I use a Holley electric pump in line on the frame rail personally.

The accelerator pump is actually part of the carburetor. You can use an electric pump on the frame rail, as you said, but then you need to delete the mechanical fuel pump. If you have both, a mechanical fuel pump failure can lead to the electric pump filling your crankcase with fuel. Not a good thing.

59 Daddy O,
Switching to a 351W is a good thing for a heavier vehicle like our trucks. If you have a mechanical fuel pump mounted on the engine, disable or remove the electric fuel pumps. If you want to keep the electric fuel pump, I would definitely run a fuel pressure regulator to make sure that the fuel pressure to the carb is within specs for the carb. Other than that, a DS2 distributor swap, if it has the TFI ignition module, and if it has original intake and carb, eventually swap in an aftermarket intake and 4 barrel carb.

Should be relatively easy, and make a big difference. Good luck.

I'm about to do the same thing except the truck involved is an '89. All of this info has been gleaned from the 1987-1996 forum.

You can bypass the high-pressure pump on the frame and use a by-pass type fuel pressure regulator with the in-tank pump, along with removing the mechanical pump on the engine and using a block-off plate.

The other alternative is to remove both electric pumps and extend the pick-up on the sending unit to the same length that the pump had, so as to pick up gas from the same place in the tank. Re-install filter sock on extension. If you go this route, I was told that you also have to crimp off the return line to the tank. Then you just use the mechanical pump. My swap is slightly more complicated in that I don't have the DS-2 wires already installed like you do.

Don't forget to get the throttle cable with the 351W as the fuel injection cable will be much too long.

Ouch, I didn't now that. Thanks for the heads up.

Ignition module and distributor as well as the engine wiring harness from the Bronco. The 302's dizzy won't have vacuum advance and it's wiring harness won't bring the signal from the dizzy to the module to tell it when to fire.

Also, IIRC the 302's exhaust manifolds are shorter due to the shorter block height. So to retain the same exhaust system you have to use the HO's exhaust manifolds. However, they are funky. There's a heat riser block that goes on the driver's side manifold outlet which makes it the same length as the passenger's side. However, it has a vacuum-controlled valve in it that is supposed to work in conjunction with another valve in the intake manifold to regulate exhaust heat to the carb. I've seen several of them but never a set that works. The one in the intake manifold carbons up and/or rusts out and becomes useless. And the controls and vacuum lines are rarely intact. I would ensure both of them are blocked open and ditch the controls since many millions of 351W's got along just fine w/o those valves. However, they weren't running that Holley/Autolite 4180 carb, so maybe that's why.

Thanks guys, I knew about the dizzy, and the throttle cable. I'm thinking I'll probably need the "Y" pipe for the exhaust, or just run headers and dual exhaust. Engine wiring harness, I'll defiantly snag that as well (I didn't think of that one), what do I do to get around the computer?

If you use the DS-II dizzy, the blue grommet module, and the wiring harness you have gotten around the computer. It may be trying to control other functions, like the EGR valve, but it can't do it properly with all else having been taken away. And the early computers had wiring that was separate from that of the rest of the truck. I don't know if that is true of yours, but is so the wiring can be removed.

That's good to know Gary. I have less than $1000.00 total into the truck so far and yesterday a guy offerd me $2500.00 for it. I might just sell it and put the money into my '59 F100, don't know yet.

That's a pretty good price. I sold an 82 with a new engine and poor paint for the same price.