engine swap out

[1986 bronco]

Hi guys i have a 1986 full size with a 302 fuel injection in it and i want to switch to a carb can any one please give me some insight to what i will be needing and if it is possible <_<

 

[cowboydan]

just curious, why?. efi is so much better. in all ways. on and off road

 

[miesk5]

yo!

Some info here;

http://www.coolcats.net/tech/advanced/tbi_conversion.html

and

http://www.jason.fletcher.net/tech/efi-carb/cfi-carb.htm

 

[Broncobill78]

Sure it can be done. Obviously you lose the advantages of EFI but you also make the systems simpler to work on/diagnose so there are two sides to it. Additionally, the early EFI systems didn't adjust very well to engine upgrades (such as cams & heads) so if you're looking to add parts to an early EFI engine it's sometimes better to swap over to a carb so there aren't any compatability problems and you're not spending time trying to get it to run right because the computer doesn't want to add enough fuel for all the additional air the engine is moving. On the other hand, swapping to a carb will make the milage go down, emmissions go up & you'll lose some drivability and horsepower.

How hard the swap will be depends on what *type* of fuel injection you have. IF it's a miltiport EFI then you'll need a new intake but it it's the CFI throttle-body injection you can pretty much just swap to a carb. Being an 86' it has to have pretty early fuel injection (unless a previous owner went thru the trouble to swap in a late model engine) so chances are it's CFI. What does the injection systems look like ? IF you have a regular looking intake manifold with a single throttle body on it then you can probably get away with just replacing it with a carb. Now chances are you'll also have to replace the distributor since the one in there will be connected to the computer. I did this with a T-bird years ago & just removed the computer, replaced the distributor & ran a carb. You have to either bypass the hi-pressure fuel pump (the one on the framerail) and just run off the lo-pressure pump in the tank or swap to a mechanical fuel pump (being an 86 it should still have the boss in the timing cover if not you'll need a timing cover from an earlier 302). You'll also need to replace the Throttle Valve cable to the transmission with one for a carb'd car or it won't shift right.

Now I've never *personally* swapped out a multiport EFI for a carb you pretty much have to do the same things except you'll need an intake manifold for a carb. You'll need a mechanical fuel pump or a low pressure electric. The distributer will have to go & you'll need the same TV cable for the transmission. If the engine is a late-model transplant you might need to not only get a timing cover that has the fuel pump mount but also add a fuel pump eccentric to the cam. I asked about this a few months back & someone who had just disassembled one of the roller 302's said that it not only didn't have the boss on the timing cover but had no eccentric so an electric fuel pump may be the way to go. I'm not sure why but I've heard from a few people doing swaps like this that the fuel sending unit needed to be replaced with one that didn't have the in-tank pump. Not quite sure what the problem was but a couple guys mentioned it. There will also be quite a bit or rewiring that needs to be done. Best way that *I* know of is to get a kit from someone like Painless or Wireworks, there are also kits on Ebay. The Multiport engines use a LOT more sensors than the CFI engines so there's just a lot more detail work involved.

 

[1986 bronco]

thxs for the info guys the main reason i am swapping is to make it easier to repair and want a 351 boss the info u guys supplied will really help thxs >

 

[BLADE262US]

The reason for having to mess with the sending unit in the tank is because the mechanical or electric fuel pump you use will have a very hard time sucking the fuel through the intank electric fuel pump and suppying the volume needed to run the motor at speed . What I did on one of mine was to take the intank electric pump off the suction line theres a collar on top of the pump just push this into the pump and it will pull off the suction line . The line is 3/8 so get some 3/8 line and a compression fitting union and bend the line so it rest on the bottom of the tank and connects with the suction line now your all set to run a fuel pump upstream of the tank . /emoticons/[email protected] 2x" width="20" height="20" />

 

[Broncobill78]

Cool Blade, Thanx for filling in that knowledge gap. I knew there was a reason it had to be modified but having never done it myself I wasn't sure just *why* it needed to be done.

 

[CSM_Bronco]

i did it to my 89 5.8

all i did was this:

headers

performer intake

HEI distributor made for ford

removed the smog pump

measured and bought new serpentine belt

rigged up some of the wiring (don't ask what i did to it, i don't even know, its that bad, but it works)

of course a carb (i went with a demon 650 vacuum secondary and electric choke)

what i shouldn't have done is ran a fuel pressure regulator off my high pressure fuel pump. (blew a line started a fire, melted all my hoses, few bucks extra and i got all new shit and it running in about 2hrs from the time it happened)

so with that.......buy a timing chain cover that has the mechanical fuel pump hole in it

then of course buy the mechanical pump. should be in the ball park of $40

all this done for around $6-700 ish. don't mark my word

thats just my two cents. take what you can from it. i'm still learning on all this two so......

simplicity is the key. there is NOTHING simple about EFI

 

[Broncobill78]

simplicity is the key. there is NOTHING simple about EFI

Well that's true but there's nothing simple about an automatic transmission either, but lots of guys like the simplicity of operation that comes with them. EFI is great when it's working but it can be a nightmare to troubleshoot when it's not. No arguement there but I think the convenience, milage, drivability, torque & HP gains balance the equation. I think the stand-alone throttle-body systems strabble the devide by using standard carb intakes & not needing the input from a dozen or more sensors.

 

[BLADE262US]

EFI is definately the way to go . Its not all that complicated . Go to www.fordfuelinjection.com and read everything you can ,understand what each sensors function is and what can happen if it goes bad . Carbs are the easy way out for those that dont want to take the time to learn . Once you figure out how it all works youll never go back there just way too many advantages . All the wires are intimidating at first but once you know where they all go your set . Thats my 2 cents /emoticons/[email protected] 2x" width="20" height="20" />

 

[bidibronco]

I have to agree with Blade. I love my EFI and I will do everything I can to not go away from it. I never like to sit in the driveway for 30 minutes waiting for the engine to warm up enough to idle on its own. I like to get in, start 'er up, let the RPM's drop and role out (like 3minutes TOPS). Nothing wrong with a carb though.

 

[Broncobill78]

Much as I hate to straddle the line I can see both arguements. While I can appreciate the simplicity and easy troubleshooting that a carb offers I grew up in New England and think maybe the guys down South just missed out on something by not ever having to sit in a freaking 5* truck for 20min feathering the throttle until the damn thing warmed up enuf to run on it's own. EFI is an amazing improvement especially in cold climates, the increase in drivability is simply amazing if you grew up with carbs and cold winters. It's nothing short of magic. For a Southern trail rig it's one thing, but for a cold climate daily driver it really does make a world of difference and truth-be-told over the years that 3 or 4 mpg *does* add up to a significant number. On the other hand, in a warm climate and for a part-time rig a carb does make a lot of sense. I once had a fuel pump diaphram tear out on the trail and drove my carb'd 460 home with a 2.5 gal gas can duct-taped to the hood. We used a phillips-head screwdriver to make & enlarge a hole to force a 1/4" bulkhead fitting into it and ran 5' of scavenged aluminum tubing down to the carb & crimped it off just enuf to let the fuel drip into the venturi. Try THAT with EFI, I dare ya. Drove it from Southern Vermont back to Central Mass that way, 200+ miles with the hood partially latched, bungee'd & duct-taped down to keep from flying up. I'm not unsympathetic to the carb crowd, it's just that with fuel costing what it does these days I think EFI is really the way to go for most rigs out there.