would you suggest going carb?

[Boss 351]

I have a rag article comparing EFI (none stock) to Carb. The power difference is 1HP and about a thousand bucks more for EFI. Fuel economy will be the same, put a small 2 barrel 400cfm carb and you will see the same MPG as the stock EFI (actually, even better MPG IMO). A nice little 600 or 650 cfm 4bbl and airgap intake will take you over 240HP with stock cam and heads (according to desktop dyno anyway).

The stock EFI needs a lot of help to get some power, the MAF computers are great systems but the intakes, TB and junk are huge restrictions. You need some good parts and more importantly someone who's really good at tuning the Ford EEC IV systems.

Remember you will need another distributor, Duraspark II or MSD box, 7psi Holley red inline fuel pump (or regulator and stock in-tank pump, or Holley 14psi blue pump with regulator, or plane mechanical pump), intake, carb, older mustang/cougar/thunderbird accelerator cable, air filter assembly, and some fuel line stuff...

I did the carb swap and the car runs real nice. I got the 650cfm double pump and an airgap style intake (runners in the air, not low down between the heads).

 

[Boss 351]

As you can see from this thread (all the threads on this topic are similar) - it's a subjective choice. The carb guys are gonna tout the upsides of carbs; the efi guys are gonna do the same for efi.

Pick what you like/are comfortable working on. It's pretty much that simple. If you like carbs/have a problem with efi put a carb on it. And vice/versa.

The only caveat I'd throw out there is with regard to emissions. Crazypete is the exception w/regard to passing emissions with the carb. In most places, the visual inspection would get you failed right off the bat for replacing the efi with the carb. And keep in mind - even though there's no emissions testing right now in some places, before all is said and done, we're likely gonna have it everywhere. Sticking with much older cars is likely ultimately gonna be the only way to avoid it.....

I wonder if you could use a carb hat, and an EFI style CAI for a carb setup? That would make it look like an EFI car (well depending who's looking lol). Or a vortech carb box?

 

[crazypete]

Whats a carb hat? Now I'm curious.

 

[fiveohGT]

Is it true that carb setups arn't good for carving corners/autox?

 

[88STANGCONVERT]

I am also thinking about the EFI to carb and I would like to know if anyone has any info on what is needed and what is not needed. I know that basics but what I am interested in is the wiring. What goes, what stays and what is added. Can you use everything with the motor except for the the intake, injectors and fuel rails? What do you do for fuel delivery? Use the same throttle cable with what bracket? Will just about any intake work with the stock type heads (for carb) or ???
I appreciate any help you all can give me.
Thanks

 

[crazypete]

The fuel sloshes around in the bowls but I personally have never had problems with it and I cut quite a few corners. Apparently if you're WILDLY nose up/down then the fuel will either slosh into the motor or uncover the metering block but dude, you really have to be pulling some extended G's to get that happeneing. Apparently draggers use side hung floats for serious tail standers as do the rock climbers in their broncos and such.

You need:
1. A carb. Holley all the way. Dont bother with anything else. Hollies are infinitely tunable. Everything else is a step down in tuneability but the factory settings are damn good and you can use it as is 90% of the time
2. an intake. I love my edelbrock performer.
3. fuel pump. I highly recommend a mechanical one with timing chain cover to match. Everyone is going to jump on me talking about holley red and blue pumps but I've done my time with dual fuel pressure regulators, 2 different electric pumps leading to alternating fuel starvation and flooding...mechanical pump went in, unregulated, I forgot it was there it has been so reliable. It just...works.....all the time...3 years..no relays.....nice low pressure that rises with rpms exactly as the motor needs it. You'll need to drop the tank and heave the efi pump and it's wiring. Put a fuel hoses in there longer than necessary to reach the bottom of the tank so it turns sideways
4. distributor with vacuum and mechanical advance and steel gear. 85 mustang
5. Ignition system to match. MSD/crane....take your pick. I think crane hi-6 makes the fattest sparks.
6. radar dish aircleaner
7. A weekend to tear out all the efi wiring crap
8. You'll need to rig the smog pump airtube to be switchless since the tab/tad solenoids are now dead weight. Just run a hose to the crossover behind the heads and cap the AIR tube injection port.
9. Throttle and TV cables. Get the lokar kits. Dont bother trying to rig. I rigged and 1.5 years later realized that the factory efi cable was only opening the throttle 60% of the way at WOT. I was kicking asses at 60% throttle.

I'm forgetting something.....

But write me if any questions arise....

 

[fiveohGT]

So there shouldn't be any problems w/ carb for regular track racing? Hmmm maybe I'll save some money and go carb. Does carb respond well to forced induction. I have future plans for a turbo setup...maybe a while until then though, just dropped over 4500 on suspension.

 

[Fishhawk]

My daily driver F-350 is EFI. Good for me because I don't want to mess with it. On the other hand I'm always testing, tuning and just playing with my 85 GT. I've gone through three intakes and two carb's and I haven't spent more then $500. For now I run an RPM with a 650 cfm QuickFuel. Just got a box of jets and I'll start changing and testing this summer. To me a carb is just more fun. Always looking for more air, more fuel, or a better mixture, with minimal cost. I have a friend with at least 12 Holleys. Last summer we took three to the track. A 600, 650, and 750. Swapped a different carb after each pass and ran my quickest times with the 650.

 

[crazypete]

"Passes" are different than everyday driving. Drag racing is about top end. Small carbs give you good low and mid end and things like idle and quick starting and throttle response. At the top, they'll starve your engine a few HP, where the bigger carb opens up and give it back. Larger carbs, however, lose velocity and with a carb it's ALL about velocity and vacuum signal. Thats how the fuel gets sucked into the motor. Thats why big carbs usually give poor idle and throttle response: it's takes a long time for a large opening to change the velocity of the air. With a small opening, the air changes velocity pretty quick.

As for forced induction, thats where carbs fall short. Apparently blowthrough carbs setups are a PITA. I wouldnt want to deal with that. You need a special carb that is sealed and you better get your mixture right on....kinda risky.

 

[Fishhawk]

"Passes" are different than everyday driving. Drag racing is about top end. Small carbs give you good low and mid end and things like idle and quick starting and throttle response. At the top, they'll starve your engine a few HP, where the bigger carb opens up and give it back. Larger carbs, however, lose velocity and with a carb it's ALL about velocity and vacuum signal. Thats how the fuel gets sucked into the motor. Thats why big carbs usually give poor idle and throttle response: it's takes a long time for a large opening to change the velocity of the air. With a small opening, the air changes velocity pretty quick.

As for forced induction, thats where carbs fall short. Apparently blowthrough carbs setups are a PITA. I wouldnt want to deal with that. You need a special carb that is sealed and you better get your mixture right on....kinda risky.

My 85 is an every day driver (now weekends only) with great throttle response and idle. A little choppy from the cam. Otherwise 800 rpm. Take it to the grocery store in the morning. Take it to the track in the afternoon.

 

[crazypete]

I personally thought I had done a super job on my carb swap. Hey....it actually ran!!! It idled and started and I drove back and forth from school 95 miles away getting good milage and kicking amherst kiddies' booty.

That was with the 670 avenger vaacum.

Last year, I switched to a 600 cfm double pumper and whoa. What have I been missing?!? And it's not the double pumper stuff, It's low throttle stuff.

They will both work pretty good. I will say that. But one setup works best for track, one works best for street. If you use that cfm x maxrpm/3456 formula then you end up with some small 500-550 cfm carbs as being what these 302's use. Heck, the nascar stockcars use 390 cfm carbs!

 

[85_SS_302_Coupe]

Hey crazypete, this site will give you an idea of just how easy blowthrough forced induction is. It's really not as risky as it sounds and can be done super cheap. http://www.toohighpsi.com/BudgetTT/BudgetTT.htm

 

[crazypete]

That setup must absolutely kick all kinds of ass but I personally shuddered....shuddered at the complexity of it. Look at all that hose and tube and oil lines and something about an injector(?). I bet you replacing plugs on that tbird/capri is as much fun as replacing them on an EFI thunderbird. I'm spoiled by a near empty enginebay and I like it for a reason. I can actually work in there. Maybe I'm clumsy or something but I just cant work on my parents' import, my GF's EFI t-bird or any cluttered enginebay. I'd rather drop a 408 stroker in there than TT it simply because it would add power but keep the complexity and underhood clutter low.

Lemme put it this way, if you have 10 oil lines....thats 20 connections that could leak. And they will cause murphy is always busy.

I always wondered how anybody tunes a carb inside a pressure box. Even setting the floats would require a mirror.

 

[Michael Yount]

stangconvert - you'll also need a distributor with mechanical advance -- the efi dizzy has no provisions for timing advance; the ecu handles it. Also, the 40 psi the efi fuel pump delivers is WAY TOO high for a carb - the carb will only want 4-7 psi at the fuel bowl inlet; so you'll have to either regulate down, or swap fuel pumps. If you choose to use a mechanical pump, you'll need to be sure the camshaft you have has an eccentric on it; and you'll need the front cover with the proper set up to take the mechanical pump.

 

[Michael Yount]

For many, many years all racers were carbed - not sure where anyone got the idea that carbs wouldn't work on race cars. Hmmm....

As with anything else, you just have to be sure the entire fuel system is designed properly. You have to have enough fuel pressure and supply to keep the float bowl full no matter the g-load on the car.

You're much more likely to have a problem with oil sloshing around and uncovering the pickup (pressure problems) than you are to have a fuel/carb problem. And, let's face it, unless you've really reduced the weight, and have radical suspension/chassis changes, most of the fox bodies probably won't corner hard enough to cause fuel problems anyhow.

 

[BlownInjected]

Throw the EFI in the trash!!!!!!!!!I have an '89 GT and dumped over $4000 into just the air/fuel delivery to the engine and never got anything to work toghether right. The car was always inconsistent, it pulled off a 10.76 once but I never could get it back to the tens.v After a ton of headaches I pulled all that crap off and sold it on ebay. I bought a Holley dominator manifold,a Barry Grant 680 carb, a Holley Blue pump, an MSD distributor and ingnition and a few other things I needed for the conversion all on ebay for less than $700 bucks..... and now the car is always in the 10.50-10.70 range and my headaches are GONE!!!!!!!!!Get rid of all that EFI crap....You'll sleep better at night

 

[Killer50stang]

yes, but the fuel milage is the only downside. Check my setup in my sig. Converted to Carb and sold all my fuel injected stuff on ebay...computer, and other mods. Got nearly $2k for everything. Used it towards my setup. Now i'm at 390RWHP compared to the high 200's I was before. Defintely save alot of money. Stay EFI if you're looking for good gas milage. Here's a pic...

 

[Michael Yount]

Like I said earlier, this will continue to be a thread where the guys who couldn't figure out how to deal with efi say 'get a carb'; and the efi guys say 'well you must have a little weiner if you can't make the efi work'. It never ends.

Put on what you want and enjoy the car.

Just filled mine up - 182 miles on 8.05 gallons - 22.6 mpg around town here in K'ville (not much stop and go). Don't believe I could go back to a carb. Ever.

 

[Michael Yount]

Killer50 - if you were only in the high 200's with the blower.....well, something was clearly wrong. And if you're comparing boosted to non-boosted set ups - well, that's not exactly apples to apples.

Curious though - what kind of intake does the blower bolt to? If you made a spacer to raise the blower up a couple of inches, do you think injectors and fuel rails would fit under it? I've always wanted to add a pos. disp. blower to mine - but the offset fitting of the KB's (to clear the distributor) won't work on mine because my brake booster sits closer to the engine than in the Stang. The blower you've got looks like it might work on mine with 1) a bit of elevation to make room for injectors/rails, 2) a shorter snout so the serpentine could drive the blower too, 3) and custom elbow/'hat' for the top of the blower to allow inlet air from the passenger side as in the regular efi set up.

By the way Killer, a significant amount of free HP might be yours for the taking (under normal driving) if you put a snorkeled air cleaner on that thing so you were pulling cooler air into the carb/blower. Even with a scoop/cowl hood, that air filter up on top is bound to pull some warm air in. You might be able to really reduce engine inlet temps which would make the blower/engine even happier. If you dyno'd with the hood open (almost everyone does) your readings are probably skewed high because of the colder air that was available with the hood up compared to what you get moving down the road.

 

[MuSTaNGPLaYR]

If you dyno'd with the hood open (almost everyone does) your readings are probably skewed high because of the colder air that was available with the hood up compared to what you get moving down the road.

I understand what your saying about the cold air giving high readings, but he accually had it dynoed on a "mustang" dyno. The name brand, its not made just for a mustang. They read much much lower than any of your typical dynojet dynoes. For dynojets you are supposed to add like 15 - 20% to see what your pushing at the flywheel. On a Mustang Dyno you have to add 36% to your rwhp to get the flywheel horsepower. FYI