What do i need to do to go from efi to carb?

[bigjim240z]

I know about removing all the efi stuff, and installing the carborated parts. What im not sure of is the fuel pump. I know from another post i made that ill need a carb fuel pump. Ill get one from summit racing. What i dont know is if ill need to pull the stock pump thats in the tank out or not? This is my first efi mustang, all my previous fox stangs were 84 and 85's. (Ive owned 4 now) I like the efi, but to get it where i want it power wise will cost me ALOT of money compared to putting on a nice 4bbl intake, holley carb and cam. Any help is appreciated!. Oh and by the way, im in las vegas, any mustang guys out this way that wanna help out

 

[shttygtstang]

no keep the efi pump get an adjustable regulator with a return . keep the efi distribtor and lock out timming its very simple. run your lines and your done

 

[bigjim240z]

What do you mean by lock out timing? The computer doesnt regulate timing on this car does it

 

[kystang1889]

Keep the efi

 

[Modular2v]

get an 85 distributer....turn ur efi pump into a pickup....get an inline electric fuel pump and route it with a 1/2 inch braided line to ur carb.....YOU CAN NOT USE THE EFI PUMP!

 

[The Fox]

and dont forget the carbed intake mani and a 600-650 carb. Use mechanical secondaries for manual trans and vacuum sec for auto. yeah and keep the EFI pump and just get a regulator to knock that PSI down.

 

[shttygtstang]

get an 85 distributer....turn ur efi pump into a pickup....get an inline electric fuel pump and route it with a 1/2 inch braided line to ur carb.....YOU CAN NOT USE THE EFI PUMP!

you can use the efi pump thats bs ive of many people doing it ....just search and read

and yes the computer does read timing im just giving you ther faster easyest solution to switch to carb lock out timing and use the efi distrbutor

 

[hllon4whls]

The best way to do a carb conversion IMO will require these parts.

Electric fuel pump, low pressure.
Fuel Tank Pickup
Dist and duraspark III from an 85 (or any duraspark dist for 302 with the right gear pressed on)
Intake manifold - aftermarket aluminum please. Stealth or Eddy RPM are good choices.
500-650 carb. 600-650 preferred.
Carb Aircleaner.
Fuel Line to reach carb.
4-8 hours of your time and basic hand and electrical tools.

 

[crazypete]

I tried to use the EFI pump with the mallory and the holley adustable pressure regulators with return. No dice. Overpowered both of them in series. Those EFI pumps are quite powerful. Theyre wild and free and dont like being regulated.

I pulled the seat and installed a HUGE resistor pack inline with the FP relay to slow that puppy down. Then I was able to regulate the FP finally but now the fuel volume went to hell. If I pulled some spirited driving, the car would suddenly die as the bowls were sucked dry.

I tried to mickey mouse this every which way and it just didnt cooperate.

Save yourself some headache. Do unto carbs what carbs desire. A mechanical pump. Why make your fuel management system mechanical then mess around with electric pumps and relays? Thats the way I look at it.

Here's what I did

I got an eccentric for the cam, a $25 mechanical pump and a timing chain cover with the hole cut out the side. You could use the efi cover since it seems to have the pod on the driver's side but not cut out. I bet you could cut the end open and tap the threads....etc. I hooked the feed line to the pump and never worried about volume or pressure again. Perfect pressure 3 years now and counting. The pump raises volume with rpm, right when you need it. It has no wiring at all, it just pumps when the motor is turning. The only PITA part was dropping the tank and replacing the efi pump with some fuel hose dropped to the bottom of the tank. But even that only took a few hours.

 

[hllon4whls]

Pete, I guess that is why most carbed OEM applications are mechanical pump.

Either way will work. Wiring in an electric pump is easy enough for me. I like the fact that you dont have to turn the motor to fill the bowls.

Leave the factory shock sensor for a little added safety. Wire in Key On position only, please.

 

[crazypete]

Actually, one thing I must say against the mechanical pump is this: you simply cannot fill the bowls by cranking. Maybe it's 100 rpms below the pumps effective speed but only once have I been able to fill the holley by cranking. I usually squeeze an eyedropper of gas down the air horns to prime it. Once it kicks in, it will fill both sides instantly. This said though, it's a mild inconvenience at best and how often does one change jetting anyway? Plus there will be plenty of gas laying everywhere when the bowls do come off.

 

[Modular2v]

you can use the efi pump thats bs ive of many people doing it ....just search and read

and yes the computer does read timing im just giving you ther faster easyest solution to switch to carb lock out timing and use the efi distrbutor

anything is possible!!! but it really is not worth the hassel to try to tame down the efi pump.....the psi is WAY to high for a carb setup

 

[gophaster]

I have run a Mallory 4307 return style fuel pressure regulator with the stock EFI pump on my carb'd car with absolutely no problems at all. I have no problem dialing the fuel pressure to anywhere between 5-8 psi with the turn of a screw. To use the EFI pump you MUST use a return-style regulator like the Mallory 4307. Works like a charm and easy as heck to setup..

I am currently running a 255LPH in tank EFI pump (b/c I added a supercharger) which flows a lot more than the stock EFI pump and guess what...the 4307 is able to regulate even this comparively HUGE pump to 5-8 psi with NO problems at all. Also, the 4307 is optionally vac/boost referenced so if you ever would like to go forced induction you can connect a vac/boost line to it and it raises fuel pressure with boost. (ask me how I know)

 

[I_AM_CANADIAN]

ok, so why must one change the dist when going to carb? and if not an 85 302, what others can I use?

 

[gophaster]

The timing in the distributor from the EFI setup is controlled by the computer. When you go to carb you no longer will be using the computer. So...you can either just lock the timing higher with the stock dist like the others have suggested, or use the 85 distributor.

I went a different route and picked up a SBF HEI distributor, this has everything built in (ignition module, coil, etc) easy install with one wire; built in mechanical advance & vac advance.

 

[crazypete]

because the EFI distributor does not have centrifugal advance, something you will absolutely need. You can use any "carbed" 302 ford distributor (I have a 76 granada dizzy) but you'll absolutely need to press the dizzy drive gear off and put a steel gear on. It will chew the teeth in 2 days with iron dizzy gears on steel cam gear and then you'll have bits of iron sitting in your oilpan!

 

[shttygtstang]

hey if you wanted it cheap and easy i gave you the quickest way. also ive heard people gaining 4 tens. in the 1/4 just by locking timing and feeling more of a grunt

 

[vristang]

Keep the efi

 

[Modular2v]

hey if you wanted it cheap and easy i gave you the quickest way. also ive heard people gaining 4 tens. in the 1/4 just by locking timing and feeling more of a grunt

4 tens? maybe 4.10s or 4 tenths?

 

[hllon4whls]

I gained a bunch by locking the timing, but I had a big problem starting the car and I run 108-110 octane fuel. I dont care about gas mileage or emissions.

As far as the regulator goes, I know the return reg will work, but with all the gas returning to the tank, how do you have enough volume to run the motor? Esp when you get up in the 7000 rpm range.

One good point about a carbed engine is that you can cheat the pump. The bowls hold enough gas usually to bridge the gap between the fuel pump flow limit and the next gear change.
To explain: If you are going down the track at 6500 rpm, and you are draining the bowls, when you shift the rpms drop and the fuel bowls can fill back up to get you through the next gear change.