would you suggest going carb?

I saw a 351W in a sixty something cobra kit car at Marc Yount's in Augusta that had a TB Injection system. It looked like and had all the room of a carb car, with a very simple FI system that looked easy to mess around with. They also they make these "computers" to tune them that are fairly cheap and easy that you can buy to keep in the car some where.

I dunno if those make the power levels compaired to EFI or Carb but I dont see how they really wouldn't/couldnt and seemed easy and cheap enough for the regular guys. Kind of like a middle gound.

Any thoughts?

Player - you misunderstand; this has nothing to do with what type of dyno the car was tested on. It has to do with the temperature of the intake air available to the engine 1) when it's being tested, vs. 2) the temperature of the intake air available to the engine when the car is being driven with the hood closed. For every 10F drop in intake air temperature, engine's make about 1/2% to 1% more HP. So whatever power it makes on the dyno with the hood up, it's gonna make less with the hood closed because the temperature of the intake air is going to rise significantly. Why do you think people use intercoolers? The more you can cool the charge air - the denser it is, and the more O2 you get in the chamber. Boosting the pressure (superchargers, turbochargers) heats the air - intercoolers remove some of that heat. In this case, if the air you put in the supercharger is at a lower temp, you get more power.

Dr.Maxit - "Any thoughts?" Yeah. Marc Yount is my brother. I just drove another 5.0L V8 powered Volvo down to him last Sat. -- he bought it from a guy here in Knoxville. Stop by and get him to show it to you.

The system you're referring to is very similar to the efi on our cars - it uses the Ford computer and sensors for the most part. What makes it different is that it has a circular mass air sensor, and a throttle body that sits atop a standard carb-type manifold just like a carb. So you can put a regular carb-type air filter on it. Otherwise, it functions pretty much just like our efi does - because it uses the same brain. It too would benefit from a snorkel type air cleaner that piped in cold air from outside the engine compartment, instead of pulling very warm air in from above the engine.

After reading all this, I want to swap to carb.

Seems that the only thing EFI has a clear advantage is emmisions, drivablility, and MPG. While carb clearly had the advantage with cost and simplisity. I could sell my EFI stuff for some $$$, enought to get a good carb setup.

Growl =)

People need to stop complaining about MPG and carbs!

If you ----->TUNE <----- it for milage, then thats what you get. But everyone tunes for power. I went on a 1 week expedition to acadia national park up in maine so I knew I needed gas milage. I got 25 mpg with my carb and 3.73s on a t-5 with otherwise stock motor, 400 lbs stripped and an eddie performer intake and msd al-6 running a holley 670 street avenger vacuum and 87 pump gas. I drove with a vacuum guage and it was all highway, relatively level about 75-80 mph the whole time. I leaned it out -4 jets (65's(64?) all around and the 4.5 power valve) and viola! 25 mpg. Even efi wont let you lean it out intentionally. But with a carb you can!

This is why I LOVE carbs.

crazypete said:

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!

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Did you have intake, heads, cam and exhaust? I ran the original 585 holley with new neddlles and seats. Rejetted it with a new metering plate for a couple months. Not enough carb. Threw on a friends 600. Ran that for a couple weeks. (On the street and track) Still wasn't enough carb. Experimented with the 650 and 750, finally found the 750 was to much. Back went the 650 and voila! It still has the low end like the 585, but gives me the fuel I need at the higher R's. Felt so confident with the 650 ProVac that I swapped out the Performer intake for the RPM. (Was supposed to lose some low end, but the only thing I lost was 1/10 on my 60', 1.8 to 1.7) Now instead of the motor crapping out on me at 4500 it is still making power. For a stock 5.0 the 600 is the way to go. Add the bolt-ons and it will be starving for fuel.

Let's see at the time of my 670.....

I had (repeating myself from above post but what the hey)

American thunder catback
Summit house brand h-pipe
mac 1 5/8 headers equals
Eddie performer intake
holley 670 street avenger vacuum
85 distributor+msd al6+jacobs coil+mech fuel pump (irrelevant stuff)
Stock original eventing else except about 400 lbs of weight removal.

The 670 was darn good, but it wasnt dominating. I went to everything in my current sig (gt-40p's, 40-p headers at that time, ported heads and intake) and it was still ok but not neck snapping but real close. I went to the 600 dp race carb and then it suddenly became neck snapping. Plus I noticed how easy it was to start the car all of a sudden.

Remember, this is an automatic so I cant rev up before I dump. I NEED baseline grunt and torque that a smaller carb gives through velocity at the lower ranges. That is a consideration.

crazypete said:

Let's see at the time of my 670.....

I had (repeating myself from above post but what the hey)

American thunder catback
Summit house brand h-pipe
mac 1 5/8 headers equals
Eddie performer intake
holley 670 street avenger vacuum
85 distributor+msd al6+jacobs coil+mech fuel pump (irrelevant stuff)
Stock original eventing else except about 400 lbs of weight removal.

The 670 was darn good, but it wasnt dominating. I went to everything in my current sig (gt-40p's, 40-p headers at that time, ported heads and intake) and it was still ok but not neck snapping but real close. I went to the 600 dp race carb and then it suddenly became neck snapping. Plus I noticed how easy it was to start the car all of a sudden.

Remember, this is an automatic so I cant rev up before I dump. I NEED baseline grunt and torque that a smaller carb gives through velocity at the lower ranges. That is a consideration.

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The auto trans might be the difference. I have the T-5. I didn't notice a cam in your sig. That also might make a difference. As far as starting goes, I'd say its about the same as it was stock, Which is just so, so. In the aera of neck snapping, I need the Drag Radials for that. Can't keep the street tires under it in the first two gears. (And occationally third) I'd say that qualifies as neck snapping.

Pete said - "Even efi wont let you lean it out intentionally."

You don't understand how the efi works Pete. One of the reasons they get better mileage (generally) is BECAUSE the efi constantly strives to lean the mixture. (Ever heard of "lean burn" design?) It is programmed to do so to help with emissions controls and to improve the manufacturers CAFE numbers. If you look at a wide band on a car at part throttle (95% of street use is at part throttle) with efi, they are constantly VERY lean - well above the 14.7 stoich a/f. It's the reason so many people with efi post wondering why their spark plugs are so white and clean - wondering if they have a lean problem. They go rich (to be safe) when you put a load on the engine (w.o.t.) - they do so because being a little rich is the safest condition for the engine. Most of us with chips/tweecer/pms adjust things for a bit leaner mixture at wot because it improves the power a bit. And if you want it even leaner - that's just a keystroke away. With the flip of a switch, you can access your "lean/highway/fuel mileage" programming without ever picking up a screw driver or even getting your hands dirty.

You don't have to change jets -- efi adjusts the mixture automatically -- cold, hot, elevation, running hard, running easy - it takes care of all that automatically - you just drive. That's why they DESIGNED it - because they realized that to meet increasingly difficult emissions standards and CAFE standards, they were gonna have to build a better mousetrap than a carb. Sorry Pete - while carbs can be tuned to achieve different things, most folks don't want to have to change jets to get their 25 mpg...

Additionally - the design standard the factory is up against is a particularly tough one when it comes to emissions. They're not simply trying to pass a one time test. They're required by law to have components that will pass emissions tests for 50-100K miles. If you put a brand new car on the sniffer it is usually MUCH cleaner than the spec's it's required to meet. This is so as time/mileage goes by and bits/pieces become less effective, they can still pass the spec.

Once again - I think each should make their own choice and build accordingly. But it's important to understand a bit of the how/why behind the systems to appreciate them. Were it not for emissions rules/CAFE requirements, I have no doubt we'd still be driving cars with carbs - for the most part.

I stand down good sir, I stand down. You know your efi's well. I actually vaguely knew about lean burn but now I know in full.

Just wanted to make a point about carbed mpg since I hear it so often as a complaint.

Oh, they dont have to change the jets to get their 25 mpg. They can jet for the 25 mpg initially and use a 9.5 or 10.5 (I use 9.5 usually) power valve. That way, it always runs lean until you need it, then the carb richens the mixture real early. Thats a crazy pete tip. Then add a huge fat 1200 Joule spark from a hi-6 shooting into a side gapped plug to burn it all and you can get the best of both worlds.

But.... I do have to say, most people would know as much about playing with fuel maps on a programmable unit as they would changing parts in a carb. And tweecers arent cheap.

Most of all, this is my major complaint about efi:

My car did "weird ****" and I couldnt figure out why. Sometimes it ran, sometimes it didnt. I was looking at an almost 13 year old efi system with 8 injectors, fuel pump, fuel pump relay, pressure regulator, tps, maf, the barometric bulb, temp sensor, (I dont know if it actually uses the other sensors) plus some relays. The problem could have been anywhere. After spending almost $900 and 2 months, I still had a car that died unexpectedly. Now I'm certain that your particular efi is sparkling brand new gleaming wires and lovingly taped harnesses running wires to beautful brand new injectors and absolute brand new sensing equiptment
.....but old grungy 13-15 year old efi wiring and gummed old sensors with frayed connectors is something else. 25 lbs of wiring I ripped out: who knows where the problem was. I replaced all that above with a mechanical pump and a box that spews gas and a stand alone epxoy sealed ignition system. I have 2 variables: fuel and spark and the spark I can test by hooking a timing light to any plug wire. The fuel I can look down into the carb and see if gas is coming out. No guesswork! Thats the part I like. I can actually see whats going on

Now you say the efi can report failure codes.....but even if youre efi reports a code.....how do you know it's right? Codes cascade, sensors get old and tired. For me, the problem turned out to be that for some inexplicable reason the ground running to the maf and computer was showing a few volts (?!? Still never figured out why). What would the tweecer show on my 91? It would say "iiiieeeeee!!! plop!" then you would be standing there digging through 25 lbs of harnesses looking for that loose connection, probing stuff looking at resistences across wires for a week. My exhaust rotted out a year before that and some unmetered air got to the drivers side O2 sensor. The car would die whenever it got hot. So you had 5 minutes or so to get to where you are going then eee and you are pushing your car to the side of the road. I mean it was dead. Now my carb wouldnt give a damn. It would just keep pumping gas if the exhaust fell out altogether.

If you have a complex system, you have many many points of failure. I'm sure 2 dozen sensors would make a much smoother system than a dozen sensors......but what happens when that system ages.....thats right, twice as many points of failure.

The brute force levers and springs technology of a carb is something I can wrap my mind around. I can actually go up to a stuck carb(?) and hit it and jiggle springs and levers and do something direct not involving parts swapping. I can blow out passages, jiggle floats, examine my needle seat with naked eye and shoot carb cleaner at the whole assembly. On the other hand if my TFI module or O2 sensor decides not to work, I can sorta stand there drooling on myself till I go out and buy a replacement. You cant DO anything to these systems to fix them without replacing expensive things.

And that was my point to begin with: simplicity is cheap and reliable and human accessible and electronics are closed box and expensive and more failure prone.

We're getting aligned Pete - the only piece I take exception to is your comment about reliability. New cars with efi and electronic ignition are more reliable than they've ever been - it's not even a close contest compared to carbs and points. Not only are tune ups essentially a thing of the past (plugs, wires, etc - routinely last 100k miles) the cars run as good with 50k on them as they did right after the 'tune up'. Heck - O2 sensors should be replaced more often than spark plugs. The real benefit comes from how much gentler efi/electronic ignition is on the cylinder/head/combustion chamber over lots of miles. Oil stays cleaner longer, and things like burnt valves (because of a faulty ignition system or faulty carb) are almost a thing of the past. It's the reason we see so many 100-200-300k mile cars these days - the engines last a lot longer when combustion is clean and consistent. You simply didn't see too many miles like that back in the day. Improved machining/assembly/metalurgy has helped too.

What you may be pointing to is that in the past if it broke down, you could often 'MacGyver' a fix by the side of the road using an empty matchbook cover and a banana peel - and at least get the car going to the repair shop. With some of the electronic stuff - if it breaks - you're in need of a tow truck. But I'll happily trade the increased reliability/durability for the need to have it towed if (much reduced possibility) if it breaks. Sounds like you've made a choice the other way. I can respect that.

For what it's worth in nearly 30 years of driving injected cars (And I'd guess 300-400k miles) the only tow truck I've ever needed was for the 5.0L in the Volvo when the Mustang throttle cable broke. And even then I only needed it cause I couldn't think to open the throttle stop screw up and set the idle speed up around 2000 rpm - I could've gotten it home that way. Didn't occur to me til I was forking $80 over to the wrecker driver.

Michael Yount said:

you could often 'MacGyver' a fix by the side of the road using an empty matchbook cover and a banana peel

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Man, that made me laugh so hard! You da man!

I remember that show! Dude, I'm having flashbacks of my childhood

It's basically this:

1) You want high-performance?
2) If yes, go to 2a, if no go to 2b

2a) Do you have a lot of cash?
3) If yes, go to 3a, if no go to 3b

2b) stick to EFI

3a) Stick to EFI and get all the proper parts to make it perform and get a good tune.

3b) Swap over to carb and get performance

Depends on how you define 'high performance' --- lots of different elements of performance.

Personally, i think the biggest difference is just plain old money. If you have the cash, you can be just as hands-on with the tuning on an EFI car as you can a carb, because you can go the laptop route and calibrate everything the engine is doing, it's just going to cost you an arm, leg and your first born to do it.

85_SS_302_Coupe said:

it's just going to cost you an arm, leg and your first born to do it.

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Or you spend so much that your wife ends up making you sleep in the car!

Edit: I am still pro-carb. I just want to do a Fuelie build up.

85_SS_302_Coupe said:

Do it. Unless you have money coming out your ass, you'll never see what EFI has to offer in a dollar to dollar comparison with a carb.


Plus you get to go from this:

To this:

And i still have a TON of unused BS that i need to get out of my engine bay.

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Did you have fun removing the EFI harness? I did...had fun getting my lights and alternator working right again!

Killer50stang said:

Did you have fun removing the EFI harness? I did...had fun getting my lights and alternator working right again!

Click to expand...

I cheated....it's a different car. I'm hardcore, i didnt swap setups, i swapped cars...lol

Michael Yount- I work at your brothers, we met the other day in the back when we were all looking at the silver mustang. Remember? I'm Chuck.

Anyways if the TBI unit I'm thinking of uses mass air like you said (I figured it was strictly for MAP only) then wouldnt that be a good compromise for engine bay room, good milage and good power? Just thinking about putting it on my 1991 Notch if i dont do EFI.

CHUCK!!!! 'Sup????

Marc thought about the system for the motor he's putting in the '85. To my way of thinking, the short runner intake you use with it probably gives up a bit of bottom end torque to the efi's long runners - and makes up for it on the other end with a bit more HP.

But I don't understand - the system the Cobra had on it is not TBI, it IS a mass-air sequential efi system just like the Stang -- it just uses carb type intake with a mass air meter that sits right over the intake. It's not much different than the box intakes or big elbows feeding a carb intake on the 351-393-408's.

Of course Holley, Edelbrock and others make TBI set ups - but I wouldn't bother with that if I could have a sequential efi unit.

Hmm.. I saw the map sensor on the firewall of that cobra so I figured it was just a ford TBI type deal. I didn't may any attnetion to whether or not it has a Maf sensor or not. I figured if it wasnt too expensive I was curious about if anyone was running it on a fox.

So Michael think you could hook me up with a running "parts car" or something to help me get my notch running?