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AMC 258 w/4.0 head & EFI |
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7Xpacemaker
AMC Apprentice Joined: Jul/23/2009 Location: Bentonville,Va Status: Offline Points: 96 |
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I have learned a lot about fuel injection by doing this Megasquirt system but I am sure that I have a lot more to learn. I agree with Wrambler that I will like the "no tune" that you get with fuel injection. If I want to tune it, I'll use my laptop. Personally, I am tired of the various amounts of ethanol that different stations can have. With that being said, it is next to imposssible to keep a carb tuned when the mixture of gas varies. I have been having trouble for the past couple of years with the Carter WA1 carbs on my Hudson. (yes, it has two carbs- "Twin H power") the carbs tend to seize up if the linkage is not exercised periodically. This never happened until ethanol. If I can get everything operating correctly with the AMC, I will be making the switch on the Hudson too. Some may think that the gas can not contain more than 10% ethanol. They couldn't be more wrong. They vary up to as much as 21%. I stopped at one chain gas station on my way to Florida in May and within 25 miles of getting the gas, my mileage went from 21.3 to 15.8 mpg. After I ran that tank out I got gas in Florida and my mileage went back to 21.3 mpg. My point to the story is this- With today's fuels it is impossible to keep all of your carbs set correctly. Just my .02 cents worth....
Edited by 7Xpacemaker - Jul/19/2011 at 6:19am |
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C.J.
1981 AMC Concord 1977 AMC Hornet AMX 2001 Firebird Convertible LS1 1978 AMC Concord 1982 AMC Spirit GT 1974 AMC Hornet |
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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Remember Doug from the Nest? Try upper 20s @ 55mph with a 258, CARB and automatic Mid-20s at 65 Top that with EFI. I've not checked my Eagle 4.0 with T5 yet, but I know it's doing pretty well from as slow as the gas gauge moves down. I checked the speedometer against my GPS device and they agree at all speeds so checking mileage should be fairly accurate after 3 or so tanks. |
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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PROVE IT. Prove it was 20% - federal law says 10% - besides, did you know that it's actually expensive to blend ethanol (unless you are in Iowa where there is a tax advantage) At least around here the dept of ag drives around with test equipment checking pump outputs and ethanol levels. You mess up, you are fined and/or closed down. I'd love for those claiming 20% ethanol to run a test and prove it beyond this "my mileage dropped so it MUST be more" bunk. So far all anyone has is hearsay, speculation and conjecture often based on "well a friend of my cousin's second wife's half brother said.......". If anyone can prove it, then do so - and we'll finally see some facts and I might believe it. |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19612 |
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I don't think there's that much variance Bill, but there can be +/- 1-2% in some states. SC allows distributors to blend the ethanol and gas themselves. We've had problems in my brother's Ford truck (98 F-250 w/351) with that fuel. After a couple tanks he has to run a good cleaner through it, so he just switched brands. We know for sure that particular distributor blends fuel himself (has several stores in the area). I'm not sure if it's alcohol content (seems to be a bit better when gas prices are down though!), the stores have water in the storage tanks (they are all fairly old), or what, but there is something about that gas! Most vehicles run fine, just a few are a bit sensitive. I can tell a slight difference in my motorcycle -- it runs okay with that gas but obviously runs a bit better with almost anything else. Not sure if FL allows distributors to do the blending or not, but when ethanol is cheaper than gasoline there is the temptation to put a little more in. As you stated, that's not often the case though. Since ethanol absorbs water there could just be more moisture in the fuel through the tanks... or on purpose.
I don't think you can compare an EFI car with a carb for fuel efficiency. An EFI car will get more mpg consistently. A carb depends a lot more on conditions, an EFI system makes running adjustments. So yes, you can get good average numbers with a carb, but check it during the worst conditions and the EFI will get better. Averaged out over a one or two year period EFI will win for power and mileage, though I don't think it will be more than 2-3 mpg. The big win for EFI is that it will put out fewer pollutants over that time period too. EFI is the main reason oil change intervals went from an average of 3K to an average of 5K (from the manufacturer) -- carbs tend to run a little rich in most conditions. A little rich is better than a little lean when you can't precisely control the fuel mixture, and running a little rich will contaminate the oil faster than the correct mixture. So there is more of an economy gain than just mpg. Of course many have the 3K oil change interval so ingrained (and the oil change stores still "recommend" it!) that the extended interval is ignored. Once an EFI system is set up it's as reliable as a carb, or more so. An owner installed system is only as reliable as the installation, and there are more things that can go wrong (wiring connections and sensors), but in general I've had no more engine control related issues with my car with EFI than I did when I was running a carb, or compared to my J-10 (with carb). It's true that if something does go wrong you can't fix it on the road as easily -- no just keeping an extra set of points/condenser in the glove box -- but then it rarely quits. |
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Frank Swygert
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Online Points: 16591 |
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Online Points: 16591 |
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And EFI is more maintenance free.....is it more efficient than a well tuned carburator? No. a well tuned carburator will work just as well as fuel injection.......but I know people will not agree with me. I used to fool with the carburators on my cars so they would start with one pump of the gas pedal......yeah, I worked on the choke and the choke pull off too....
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19612 |
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The carb is only good for a comparatively narrow range of conditions though. Within those conditions I agree with you -- a carb is as efficient as EFI. Outside that range the carb starts to fall off -- more so as the conditions get further from the tuned range. That doesn't happen with EFI. That's why the guys at the track have portable weather stations and tune carbs all day long, to keep as close to an ideal mixture (for power) as possible. A street car is tuned to operate in a wider range, but still falls off efficiency as conditions change. Most people buy a carbed car and leave it alone. If you're a real carb guru you could probably tune it 3-4 times a year and stay closer to the most efficient range, but most simply won't or can't do that. So a carb is at it's most efficient range MAYBE 20-25% of the time at best, depending on how much the weather changes in a particular location. Down south here 20-25% is probably about right, the further north you get where there are wider extremes in temperature the more that percentage of time when the carb is "right" is going to fall off.
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Frank Swygert
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Thikstik
AMC Addicted Joined: Mar/20/2008 Location: Alabama Status: Offline Points: 1327 |
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Re carb efficiency...I agree that efi AND computer control win out. Consider that carbs run super rich when choke is on...and most dont have perfect adjustment. I love getting a near perfect driv-off on a cold day with 1 half throttle pedal tap , then one more tap to calm down the hi idle step. But sure, its not as perfect as efi. Alot of carbs in the past had aneroids for barometric pressure adjustment and they had hot idle compensators for , well, hot idle conditions. Thats neat stuff, but most carbs dont have such things.
Re fuel. Maybe some of the problem is octane varience. Maybe some of it is moisture. I personally experienced some gas from a Shell that would not even light off if poured on the ground. This was on a 4 wheeler single cyl engine that a buddy said just quit when he used their gas. It never even sputtered despite hot ignition. Pulled plug and cleaned/dried and it woudnt spark AT ALL. Thats when we poured gas on ground , and it wouldnt light! The carb had to come off and be totally purged and spark plug tossed, and new gas b4 it ran. I couldnt believe it. Station was getting all kinds of complaints and new cars were stalling , but mostly just running rough with CEL on. My theory on that gas was that the nitrogen and water was forming some strange brew . (they have that nitrogen cleaner). It was just at that 1 station.
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75 gremlin x, jeep 4.0 headed 258,
264H Cliff cam, intake,header. 390 holley. I want a 282 VAM motor! AC/PS/PDB. 72 AMX , 304 2bbl, 3speed, now disks...probably will sell, want an automatic /AC. |
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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>>Since ethanol absorbs water there could just be more moisture in the fuel through the tanks... or on purpose.<<
LOL - one has to wonder what ELSE is in there........... EFI is richer when cold, too..... thus the temp sensors all over the place. It simply takes a richer mixture on a cold engine. Maybe some folks just don't like setting up carbs properly, or the thinking and measuring involved. But a good carb with proper settings will start, go, and not have issues like so many describe. Wonder why all drag racers running classic or older cars aren't converting over to efi? |
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7Xpacemaker
AMC Apprentice Joined: Jul/23/2009 Location: Bentonville,Va Status: Offline Points: 96 |
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TWO new cars were taken to my friends Chevrolet dealership in northwestern Pennsylvania because one would barely run and the other would not run at all. Long story short- the gas was drained out and a sample was sent out from each vehicle. It turned out that there was 21% ethanol in the gasoline. You can take or leave my information or call it "hearsay", it matters not to me. No matter what I say it is all hearsay to anyone else. I have also gotten good mileage from carb'd vehicles as well. My daily driver (84 miles per day) was an '81 Concord/ auto with a two bbl carter. The best I could get out of it was 22 mpg at 70 mph. I had the car tweaked as close to stoich as I could without detonation. I am an aircraft mechanic by trade and definately have the skills to properly set up a carb. My intention when adding to this thread was not to stir up other people's emotions. I apologize if I have. I sometimes come across wrong, I guess. |
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C.J.
1981 AMC Concord 1977 AMC Hornet AMX 2001 Firebird Convertible LS1 1978 AMC Concord 1982 AMC Spirit GT 1974 AMC Hornet |
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