CFI to CARB-Advantages, Disadvantages

[Merc302]

1985 Mercury GMarquis 302 CFI
147k

Its pretty much running straight. 1 or 2 minor issues(slight vaccum leak in cabin, i believe it to be cruise control,also TPS doesnt work right. Either holds throttle almost wide open or not at all and throttle kick solenoid is bad.) Heat doesnt get hot ha. Although the coolant is circulating. Even before i removed the thermostat it didnt get hot but as far as i can tell there are no leaks. I will pressure test it when i get the chance.

Thats pretty much the specifics on my car.

A few suspension kinks i have to work out(i say work out because i dont know what those kinks are)

But I want to convert the vehicle to carb for personal preference and ease of maintenance reasons.
I just dont know exactly how to do away with the CFI system and convert it.
Need some help, you all have already been so accomadating and helpful already.

[86VickyLX]

Refer to other thread you made lol. Also, no thermostat makes it run weird, and cold, put a 195 thermostat in it, and be done with it.

The vacuum leak you're hearing is probably the automatic parking brake release. Move the shifter, does it hiss?
If so it's the release.

[Merc302]

It hisses full time as long as its running. My parking brake operates fine

[johnunit]

"heat not getting hot" is probably a clogged heater core. All you can really do is very carefully flush it with a rad flush, reverse direction.

+1 on the lack of a thermostat doing weird things. Keep in mind that this engine knows how hot it is, so if you're keeping it overly cold it will stay in warm-up mode the whole time.

In general where is the hiss coming from? driver's foot well? passenger foot well? in the engine bay?


If you really want to go carb, you basically have to take everything fuel-related and put in carb stuff. New intake, new carb (obviously), new fuel pump, pull in-tank pump, etc. Your distributor may be adaptable but it's probably easier to just get all new/junkyard duraspark II wiring and distributor and box.

[P72Ford]

I gave you some feedback in one of your other threads, on the carb swap. Advantages and disadvantages are a matter of opinion. If you have fiddled with carbs, or are willing to try it, then go that route. Do a carb if you are not comfortable with pulling a wiring harness apart, or messing with wiring at all. If you haven't messed with carbs, or are not capable of fiddling with them, and don't want to learn, then don't do a carb swap. Carburetors are not a magical 'fix all.' They still require work, and tuning. If you think its bolt on and go, you are setting yourself up to have the same driveability issues you have right now. Some carbs run good 'out of the box.' Some require work.

If its a street car, always run a thermostat. There is no reason not to. The car won't run cooler, it will just take longer to warm up, which means it runs crappier for longer in the morning.

You need to focus on one project at a time. Prioritize, and chip away at your projects gaining knowledge as you tackle each task.

I am not busting stones here, just trying to give you some direction.

[Merc302]

I gave you some feedback in one of your other threads, on the carb swap. Advantages and disadvantages are a matter of opinion. If you have fiddled with carbs, or are willing to try it, then go that route. Do a carb if you are not comfortable with pulling a wiring harness apart, or messing with wiring at all. If you haven't messed with carbs, or are not capable of fiddling with them, and don't want to learn, then don't do a carb swap. Carburetors are not a magical 'fix all.' They still require work, and tuning. If you think its bolt on and go, you are setting yourself up to have the same driveability issues you have right now. Some carbs run good 'out of the box.' Some require work.

If its a street car, always run a thermostat. There is no reason not to. The car won't run cooler, it will just take longer to warm up, which means it runs crappier for longer in the morning.

You need to focus on one project at a time. Prioritize, and chip away at your projects gaining knowledge as you tackle each task.

I am not busting stones here, just trying to give you some direction.

thats what i need is direction. I know you guys have already given some input. I swear i HAVE listened and considered. Thats why i decided on carb finally.
I think most of my drivability issues are taken care of.

I want to do this swap im just clueless as to where to start first exactly.
I plan on pulling the motor within the next month or so for all the little things i wont wanna do later. Ill do the chain then. along with a pan gasket while i have it out.

[Merc302]

"heat not getting hot" is probably a clogged heater core. All you can really do is very carefully flush it with a rad flush, reverse direction.

+1 on the lack of a thermostat doing weird things. Keep in mind that this engine knows how hot it is, so if you're keeping it overly cold it will stay in warm-up mode the whole time.

In general where is the hiss coming from? driver's foot well? passenger foot well? in the engine bay?


If you really want to go carb, you basically have to take everything fuel-related and put in carb stuff. New intake, new carb (obviously), new fuel pump, pull in-tank pump, etc. Your distributor may be adaptable but it's probably easier to just get all new/junkyard duraspark II wiring and distributor and box.

Its exact location is off the brake pedal. behind some plastic shit. there is a vaccumm line on the pedal side and on the back is where the leak is.
Brakes work fine minus the need of a fluid exchange(stuff looks like oil)

[1990LTD]

Its exact location is off the brake pedal. behind some plastic shit. there is a vaccumm line on the pedal side and on the back is where the leak is.
Brakes work fine minus the need of a fluid exchange(stuff looks like oil)

sounds like the automatic parking brake release. they're vacuum actuated and designed to pop the parking brake off when you shift into a drive gear.


no heat or weak heat could be anything in the cooling system but my money would be on the heater core since it's the "last stop" for the coolant before you get any of its heat.

[johnunit]

That does sound like the parking break release. It's a little greyish semi-circle thing. Just pull the vacuum line to it and plug it and forget it.

[1990LTD]

That does sound like the parking break release. It's a little greyish semi-circle thing. Just pull the vacuum line to it and plug it and forget it.

yeah a golf T or a vac plug from the HELP aisle will do nicely. I've been meaning to plug mine because it hisses but operates otherwise normally. I don't use the E-brake so I don't need it.

[Merc302]

Well I admit i dont know. but the parking brake operates normally. I was told it could be related to cruise control

[86VickyLX]

Well I admit i dont know. but the parking brake operates normally. I was told it could be related to cruise control

Step on the parking brake, start the car, put it in drive. BAM
Disconnect it if you want the hissing to stop.

[Merc302]

Alright. Theres a vaccumm line on the FRONT of the pedal assembly. THATS the parking brake release. my leak is coming from BEHIND the pedal but definitely off the pedal.

[86VickyLX]

Alright. Theres a vaccumm line on the FRONT of the pedal assembly. THATS the parking brake release. my leak is coming from BEHIND the pedal but definitely off the pedal.

There's a horseshoe plastic thing, cap the vacuum line going to it, and bingo, no more leaky.

Oh and you said Jacks, you don't mean bumper jacks do you?

[Merc302]

Will that have any negative effects? no, i mean double pump hydraulic floor jacks.
I wont get underneath a car with bump jacks