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Discussion Starter #1
I know of the usual benefits of EFI, but I have a specific, maybe off the wall concern. My 289 has pretty typical performance parts, cam, manifold, 351 heads, Edelbrock 600 carb. Maybe I'm gettin' old, or maybe it's my particular cam/carb combo...but I have an issue with the general smell of gas and exhaust. I can smell the gas venting from the gas cap. OK, I know that's just 1965 technology. I can smell gas at the carb, and I realize the fuel bowls on the Edelbrock carb are essentially free to vent under the hood. And the exhaust smell is simply the fair amount of overlap from my old-school 221 degree "276" cam. Makes yer eyes water. (My previous milder "256" cam was not nearly so smoggy).
To the point...I think an EFI swap(hydrocarbons vent back into tank) and a modern roller cam would be a "cleaner" ride, smell no worse than a 90's 5.0? Any EFI guys notice this after their swap? Thanks for your input!
 

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You are clearly suffering from OTWC, induced by green propoganda that thrives in your locale ;) Your initial diagnosis is correct: you have OTWC (off the wall concerns).

A better solution than EFI would be to get your engine properly tuned. It is not your cam that makes your eyes water from exhaust fumes. Instead, it sounds like your ebrock carb is in need of some serious tuning, including float levels and jetting.

Why would a roller cam (modern or ancient) be any cleaner? Are you looking for a reason build a race engine?

FWIW, I run a NA motor with a little bit of power. My eyes don't water when the engine is running, unless I am just smiling at the sound of a SBF ;)

randy
 

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Discussion Starter #3
Ha! Well, I'm not thinking of saving the earth, just my few remaining brain cells. The car runs pretty well, I have a spent few weekends with floats, metering rods and timing. Plugs are a nice ash gray, lots of response. Maybe it's just the nature of the beast?

As for the roller cam, more lift with less overlap. So less unburned gas at idle and low RPM. The roller 5.0's seem to run well with EFI. I had considered a split duration cam, with a little shorter duration on the intake as an economical fix...but the thought of EFI (and no venting to the atmosphere...and I walk into the garage with no gas smell...Hmmm?
 

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Let's put it this way: it will run better cold, it will run better warm, it will smell better, it might even make more power everywhere in the power band. This all assumes that you do it right, of course.


As for you plano... you can sh*t in your yard all you want, but if the fumes stink up my yard I have a right to say something about it. ;)
 

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hydrocarbons vent back into the tank? I dunno, it seems everyone on here who did the efi swap (including me) just ripped off the emissions things (Charcoal canister)..

As for venting from the gas cap, I'm still confused about this.. WIth EFI, and possibly with carb, how can you not have a vented gas cap? If the fuel goes out and gets burned, you have to fill up the tank with air. Otherwise, you'll create a vacuum, and not suck fuel, or, possibly worst case scenario, the tank will collapse.. What am I missing here?
 

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There is a VERY good reason why new cars use EFI. First, yes you eleiminate fumes and wasted raw gas. Fuel economy is MUCH better and as stated earlier, it runs the same cold or hot. AS far as power? It's all in the tuning, the stuff about carbs making more power is largely a thing of the past (carbs are cheaper, that's all).

People like to criticize it because they don't understand it. I plan to upgrade to some sort of EFI (390 GT) as soon as I see something that doesn't require a rocket scientist to install and tune. That BOSS system looks prtty promising...

http://www.retrotekspeed.com/products/bossefi/bossefi-system/bossefi-single-quad.html
 

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I was looking at that same BossEFI system the other day. Not only is it about $700 cheaper than either Mass-Flo's or Edelbrock's EFI kit, but it's more stealthy, letting you keep your existing intake manifold instead of getting a new one with fuel rails welded to it. And since they offer a version that doesn't need a return fuel line, the computer must be pretty accurate. It shouldn't be any harder to install than a new 4bbl carb.
 

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Before you get too excited, why not replace the hood to cowl seal on your car with a fresh one. Of course it's quite possible you don't even have one at all. If it is missing or crummy, all sorts of nasty fumes get sucked into the car's interior through the cowl vents. While you're at it, you'll want to make sure the fit of the hood at the rear is close enough to where the seal is functional.
Secondly you might take a look around your shifter and look for missing plugs in the floor pans. A suprisingly small opening in the floor pans or transmission tunnel can let all sorts of fumes in. Exhaust fumes can even revert into the trunk area and then on into the passenger compartment.
I have personally had all these problems make my cars stink inside while driving. Once the openings were taken care of so was the smell. SWMBO's Fox Mustang at one time reeked of gas fumes while driving, windows open or closed. A new cowl to hood seal fixed it right up. I was going to reinstall the missing factory charcoal cannister setup but it turned out to be unneccesary. I'll probably put it on sometime anyway, since I already bought it.
 

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A lot of folks complaining about exhaust or fuel smell have rear trunk seal problems. Midlife doesn't, except last Saturday, when I inadvertently forgot to close the trunk lid. As I went for my 11 mile loop, I could smell exhaust...not strong, but it was definitely there.
 

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An excellent point! And one I forgot. Also our old cars have "vented gas caps" which happen to vent gas fumes right under the edge of the trunklid.
 

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Discussion Starter #12
I'm not exactly sure, as I don't know much about EFI, except that I recall an article that showed an EFI swap with a return line of some sort to the fuel filler pipe(?) I just assumed it sent vapors back into the tank (instead of the garage 24/7
 

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Discussion Starter #13
Yup, it's that old vented cap I smell. And the carb. Both smell even when the car sits for days. That's my issue, not so much when I am driving around.
 

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Discussion Starter #14
Thanks for everyones' input, I appreciate it.

I agree about all the seals and gaskets for exhaust fumes. But, I don't get any exhaust fumes in the car unless I come to a stop and they waft into my open window. Under way, cruising, no exhaust fumes...though a cop pulled me over once, nice guy, was following and thought I had a big gas leak, but nope, just the cam.

The smell of gas is when the car is not running. Its vapors from the gas cap and the carb, strong after I shut off, but always present.
 

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BluEuc said:
I'm not exactly sure, as I don't know much about EFI, except that I recall an article that showed an EFI swap with a return line of some sort to the fuel filler pipe(?) I just assumed it sent vapors back into the tank (instead of the garage 24/7
EFI Pumps a lot of fuel up to the engine, where it goes to the injectors, and then through a regulator. All unused gas goes back to the tank. Mine is in the drain of the tank, but someone recently asked if there would be a problem with the weight of the fuel preventing it from returning correctly.. Not sure about that one.
 

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My car does the same. It's a 200 six, mild cam installed. I was on El Camino Real and at stop lights yesterday and the same thing for me, exhaust fumes waffle in through the window as I was waiting for the light. All seals are good and hood is straight on.

After I park a while, when I get in the car, I smell gas fumes. Once underway, it's all cleared up.

I haven't driven the car in a few years so I had forgotten about all the fumes. I am definitely considering one form of fuel injection if I do a 302 swap.
 

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BluEuc said:
To the point...I think an EFI swap(hydrocarbons vent back into tank) and a modern roller cam would be a "cleaner" ride, smell no worse than a 90's 5.0? Any EFI guys notice this after their swap? Thanks for your input!
I feel your pain BluEuc. I just finished a complete restoration of my fastback (blasted, painted, all new seals, tank, cap, Ford Racing crate motor, Magnaflow exhaust, fuel lines, carb ...). It has been dynotuned and then tweaked again after some miles and runs great.

That said, I'm going EFI. Not only could the mileage be greatly improved, but it runs like a beast until it is fully warmed up (even with working automatic choke). Maybe I'm getting old as well (is 38 old?), but I'd like it to be a bit more civilized. As a side benefit, it would be nice if it smelled a bit better.

Good luck with yours!
Jeff
 

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My previous '65 was mostly stock except the previous owner tossed the 4100 for a generic Holley. I never noticed a gas smell from it but I did get some fumes after refuelling. I think this is an indication the filler neck hose needed to be replaced. It was probably 40+ years old...

I have to admit, the only car I had that had a performance cam was a '69 Firebird and it was a factory Ram Air III cam. I don't recall smelling gasoline fumes but I wonder if it's just my fading memory?

Dean T
 

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Hmmm. Something to think about is with an EFI swap, you'd STILL have a vented gas cap making fumes back there. Underhood EFI is a closed system so you would be eliminating fuel fumes up there.
If you have a chance to look at something like an '85 Mustang GT with the ai cleaner removed, you'd see a Ford/Holley 4180 carburetor. The bowl vents are not vented to the atmosphere like aftermarket Holleys, but to hoses that lead to the charcoal canister. In addition such a GT also has a tank vent line that runs the length of the car to vent those fumes through the charcoal can too. (I have a 4180 in the garage though I think I tossed the vent hoses and SWMBO's car is a "counterfeit" '86 GT).
Seems to me it wouldn't be a terribly hard project to add a charcoal can to a car and the necessary hoses if you wanted. The one from the tank wouldn't be too fun to fabricate though. I've heard that some '60's California Mustangs had tanks that were vented somewhere other other than just through the cap, but I've never seen the setup. No doubt someone here has. Such cars might also be donors for some direct swap fuel vapor controls.
As an aside, EFI "return" lines return excess fuel at low pressure to the tank (not fumes). This supposedly keeps the pump from working so hard as it can work at a consistent set pressure, the excess is constantly bled off. Also this recicultaing of the fuel is supposed to keep it cooler. Not all EFI setups have return lines. A '90's Dodge Neon for example has a "dead head" setup without a return line. Apparently for most purposes it works just as well.
 

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Here's my take on EFI vs Carburetor.

A carburetor is essentially a mechanical computer. It uses various analog inputs, primarily throttle position and amount of vacuum and "computes" an output of fuel as determined by the "programming". The programming consists of jets, power valves, accelerator pump size and cam choice, secondary settings, etc.

A modern efi setup simply replaces all of the mechanical programming with digital programing. At the same time it incorporates additional inputs that were not directly possible with a mechanical computer, such as coolant temperature, barometric pressure, air/fuel ratios, etc. Obviously the digital solution is a much cleaner approach. That's the reason that no modern car uses a carburetor. With the sensors and programming avialable, the fuel curve can be tuned to make the car burn gasoline in a much more efficient manner. This, in theory, should reduce hydrocarbon emmissions significantly. While really good carb tuner could approximate the tune of an EFI at any given condition, it would be impossible for the carb to maintain this tune as environmental factors change (like altitude, road grade, and temperature) as well as various other factors like fuel octane rating, engine temperature, etc.

On top of all that, a modern ECU does a much better job of controlling the ignition and fuel subsystems together, which is critical to engine efficiency.

My hat is off to Donát Bánki and János Csonka, but let's face it. If the ECU would have existed, they wouldn't have needed to invent the carburetor.

Phil
 
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