Alright so I bought a 1987 F150. Within a month the oil pump dropped giving me the perfect reason to rebuild current 302. Now I'm converting the engine to carburation and am in need of assistance. I have the car, intake and plans for the fuel system using a mechanical pump.


My problem is this: I have read several articles and forums where people have performed the same task that I am doing but I cannot find answers.
When it comes to the ignition system can I stay with the TFI for now or do I have to switch to a Duraspark system???? Thanks for any advice!

 

I'm pretty sure you need to swap to a stand alone ignition system. Dura spark or aftermarket.

 

Thanks man any ideas how I should go about that? Duraspark is what I'm leaning towards

 

Okay so I'm thinking about running with the Duraspark setting. It seems fairly easy to hook up. But another route I was looking at was an HEI Distributor. One wire runs it... would that work??

 

HEI should work fine but be aware that many of the cheap ones don't seem to last long. DUI makes a good one but kind of pricey. You get what you pay for!

 

DS2 ignition (20+psi turbo boost and no issues)
87 truck should be iron flat tappet cam, use the dizzy gear from the original tfi to be safe.
Can use current electric fuel pump, just add Mallory 4309 regulator and adapt to the feed and return lines.
Computer grounds the the negative on the relay to control the fuel pump. Run your own ground to the relay and the pump will run with key on. Check to make sure inertia switch still works/disables fuel pump.(unbolt and wack on your palm)

Don't use an old timing cover with a mechanical fuel pump opening the angles for coolant flow are usually different than a reverse rotation pump and cover.(if you go mechanical fuel pump)

Use an intake mani with crossover heat if in a cold climate.

 

You can run the tfi and carb (have done it twice) but have no timing control, it basically a locked dizzy. These were both on turbo deals.

Now would be a great time to step up to a roller cam if not equipped. Roller cams and carbs go great together in my book.

Factory truck cams tend to be long duration low lift. Bad for mileage but less chance of pinging with the later intake valve closing. It also help them rev as you would when towing to get the most speed before the shift.

The mustang h.o. roller cam is perhaps the best and most versatile cam for the 302. I tuned an 85 mustang, h.o. cam and holley 4bbl. Customer said 21 mpg with 4.10 gears and stock efi mustangs couldn't touch it.

You will give up some bottom end with the short carb intake runners vs long efi runners. A shorter duration cam with more lift will help.

 

Just remembered...If you go factory steel roller cam and ds2, the ds2 dizzy gear has a different i.d. than the tfi dizzy gears. So getting a factory roller steel gear from a roller mustang tfi dizzy will not fit the ds2. Check the o.d. on the ds2 dizzy where the gear rides, and get the appropriate steel or bronze gear.

Did one of these last summer but don't remember which gear it was. If I figure it out will post it.

If you stay flat tappet, should be able to use the gear that comes on the ds2. Always check materials for compatibility. I purchased a cast iron roller cam for a 351w and the cast is different than the flat tappet cams and requires a different gear material.

 

I ran a HEI distributor from Proform for years in my 88 F150. I never had any problems.

 

Did an ebay hei on a 351w with an h.o. roller cam about 2 summers ago. It was said to have a composite gear, so compatible with steel or cast camshafts. Very simple and worked well.

I cannot get over how ugly they are tho. It was on a restored 37 Ford 2 door. It would be the first thing to go if it was mine lol.

Can also go pertronix in a ds2 dizzy if your worried about looks. Very simple just need a dizzy and coil.

 

If you have power steering and such you can't run a mechanical pump as the bracketry is in the way.

You can't run the stock pump with regulator, as the return line is too small and you won't be able to get the pressure down to 6 psi. Lowest I got was around 10 psi. I ended up putting a small electric pump in place of the stock pump that way it was already powered with key on. Worked fine. I did not use the return lines, just plugged it off.

I used a duraspark distributor and box. I found a key on power source for the box and make my own loom to plug in a stock duraspark distributor(like a late 70's 302 version since your motor is flat tappet just like a 70's motor). The ends are getting hard to find, but a buddy had a parts car that I used the plugs and soldered up a pigtail so everything plugs in. That way when somethind quits(like my new box did) I just plugged in another one. Don't hard wire it or use butt connectors as that will be a PITA to change when it dies(it will).

 

Did this on an efi Ranger and efi t birds without issue...perhaps the f150 has a bigger pump or the longer return line produces more back pressure.

 

In theory, you should be able to drop the fuel pressure to carburetor levels. In practice, this is not quite so simple. The problem is the EFI fuel pump can develop quite a bit of pressure. The Bosch 69100 which is the frame rail mounted pump can deliver far more than the 30 or so PSI needed to operate the EFI system. The regulator on the fuel rail will be gone should you eliminate the EFI, so you are dealing with the raw output of the pump. Bringing this down to something around 5 PSI for your carburetor requires one heck of a regulator.

There are two common types of regulators. The factory EFI unit mounted on the fuel rail is a bypass type and requires a fuel return line to the tank. There are non return line regulators which work somewhat like a gas welding regulator, but these depend on flow to regulate and can overpressure with no flow easily by the nature of their design.

Your 87 F150 uses a 2 stage pump system where you have a lift pump in the tank and the frame rail mounted high pressure pump to provide EFI level pressure. There also is a complicated valve that depends on the pressure and flow from the in tank lift pump to select front and rear tanks.

So, going carbureted on your truck may not be as easy as it seems, but there are ways to deal with the fuel issues. The in tank lift pumps will deliver something close to 10 PSI and obviously must pass sufficient volume to run the engine. There is one in each tank, but there is only one high pressure pump mounted on the frame rail. The solution would be to eliminate the high pressure pump, which is overkill for your carburetor and add a bypass type regulator from the output of the fuel tank switch which will regulate the 10 PSI down to something less than 5 PSI that will make your carburetor happy. I would not suggest using a flow type regulator because the static pressure could build to maximum fuel pump capacity which may overwhelm you carburetor. Of course, you can use the factory return line with your new bypass type regulator and the line sizing should be adequate for what you need.

I did have exactly this experience with a friend who had a street rod and wanted to ditch the original builder's EFI system for a more traditional carburetor setup. I do think you should check your reasons for removing the EFI. It will take a lot of tuning to even approach the driveability and power of the EFI system with a carburetor. If you think it is simpler, well, to each his own but I find it far more difficult to source parts, maintain and tune a carburetor than it is to do the same with an EFI system. Sometimes, like my friend did, there is simply the reason of nostalgia and tradition for making such a swap and if that is you ideal, well have at it.

 

I always wondered what the in tank pumps were rated at. I suppose I could have gotten away without a pump up front, but didn't know the specifics of the in tank pumps.

I used an Aeromotive return style regulator, but since the return lines are so small you can't return enough fuel to get it down to 6 psi even though the regulator stated you could. The regulator requested 3/8" return line. Stock is what 1/4"?

 

That is something like what I experienced with that street rod swap I mentioned. I recall it was very difficult to drop the pressure to carb levels with the EFI pump. The solution we ended up with was to eliminate all the pumps and regulators and return lines and run a mechanical pump. SBC bellybutton motor, of course, but the theory holds for any EFI system.

Interesting point on sizing the return line. I wonder if it would have been any easier with lower primary pressure?