ConcoursMustang Forums
1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1966 Mustang => Topic started by: bryancobb on December 05, 2011, 08:00:19 AM
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These guys on VMF are trying to tell me I should be getting better than 20MPG on my concours, stock, 66 C-Code Convertible, with C-4 Automatic.
I can't remember the gears I have in the rear, but it was the normal bone-stock ratio...I think? 2.73 ??
Are they blowing me smoke? I was under the impression that 11-13 would be more accurate.
http://forums.vintage-mustang.com/vintage-mustang-forum/636830-calling-all-engine-experts.html
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Bryan,
The stock gearset is most likely a 2.80. I had the same setup as you (interestingly enough, my car was also Nightmist Blue), and I regularly knocked down 22-23 mpg with a stock 289, C4, and 2.80s. The car didn't have A/C.
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My 68 fastback with 289 auto and 2.79 gears gets 15-17 mpg. In 1974 I had a 1967 GTA coupe with 289 auto 3.00 gears that got 20+. That was leaded gas. Today if I use Ethanol I can count on a mile or two less mpg. Five years ago we had a 67 coupe 200 6cil with auto and 2.82 gears it would get 22-23 mpg.
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I STAND CORRECTED THEN. If you guys want to read the thread there, and see if you can help me find why I am running slobbery rich,
by all means contribute. I'm at the point that I am thinking somebody may have enlarged my jets in the past or something.???
http://forums.vintage-mustang.com/vintage-mustang-forum/636830-calling-all-engine-experts.html
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I'm getting 18MPG in my '65 w/ 289 C-4 & Autolite 4100.
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I drove from Massachusetts to California in a 66 Mustang "A" code Fastback, 4 speed, 3.00:1 rear axle. Here are the numbers: distance - 3,177 miles; fuel used - 176 gallons; driving time - 48 hours; ave speed - 66.1 mph; mileage - 18.1 mpg. I got at least 10 hours sleep each of three nights stop (Joliet, Ill; Cheyenne, Wy; Ely, Nv). I learned to keep traveling records, mileage, costs, etc, from my father, a WWII USN pilot.
My 66 "A" code hardtop, C4, gets 13.1 mpg in mostly city driving with the lousy California gas. This is over 20 years of records. My 66 "K" Fastback has a 10.4 mpg average but is only driven about 250 miles a year (mostly up the street to "stretch its legs"). Anyone who claims over 20 mpg in a Mustang V8 needs to get their mileage using at least 1,000 miles worth of consecutive records.
Jim
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Here's my tag. I am not absolutely sure the gears inside are what's shown on the tag. My carrier came out of a 67 and it's the wrong one. I intend to get the right 66 unit in the future.
Can some of the experts tell by the pics what gear set I have. I wish I had counted teeth when I had it out.
(http://i950.photobucket.com/albums/ad350/bryancobb/tag.jpg)
(http://i950.photobucket.com/albums/ad350/bryancobb/machinedspots.jpg)
(http://i950.photobucket.com/albums/ad350/bryancobb/piniondone2.jpg)
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Your Tag indicates a 2.80 gear ratio. The top W# is the axle model, to the right of the gear ratio is the Date ( year-month-week) The last number grouping is the plant coding. The best every, freeway, in my stock, 65, GT, 4 spd is 19 MPG. Two previously owned stock 66, C code autos, right at 15 MPG. Just about the same for a stock 66, 6 cyl. auto I owned for 30 years. I think todays terrible gas, California, and the awful stop and go traffic really takes a toll on getting any kind of decent milage. With the 428 CJ: never checked. Brian
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My car is a MAR 66 Metuchen car. I'm pretty sure the TAG and axle housing and axles are original to my car.
The differential has obviously been changed. I'm not sure what I have. Maybe a REAL SHARP expert
could see enough detail to tell me what ratio I have.
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I STAND CORRECTED THEN. If you guys want to read the thread there, and see if you can help me find why I am running slobbery rich,
by all means contribute. I'm at the point that I am thinking somebody may have enlarged my jets in the past or something.???
http://forums.vintage-mustang.com/vintage-mustang-forum/636830-calling-all-engine-experts.html
Bryan, DID Kurt run test your carb?? he should have noticed any enlarged jets during the rebuild/restoration and run test.
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How about some basics. What is the number on your carburetor? Did you open it and verify the jet's size? They should be stamped "50F" and have a hole diameter of 0.049inch. Over time they get "smaller" with a build-up of gas additives and other crap that in there. Many mileage problems can be traced to a blown (or leaky) power valve too.
Jim
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Recall, in my parents factory 65 convertible they had in the late 70's, getting low 20's (think it was 21 or 23 on a long trip one time - fairly flat trip to so Cal.
A code 4 speed unrestored car that Ford purchased from them as a contest car in the 80's
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Bryan, DID Kurt run test your carb?? he should have noticed any enlarged jets during the rebuild/restoration and run test.
You may know more than I, but I don't think Kurt has the capability to run a carb on an engine.
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How about some basics. What is the number on your carburetor? Did you open it and verify the jet's size? They should be stamped "50F" and have a hole diameter of 0.049inch. Over time they get "smaller" with a build-up of gas additives and other crap that in there. Many mileage problems can be traced to a blown (or leaky) power valve too.
Jim
Jim click on the link above and go read the thread on VMF. There's pictures of it.
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At this stage, replace the carburetor with an off the shelf rebuilt one and see what you get.
Jim
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You can get close to knowing the rear Axel ratio by jacking up the rear Axel and counting the tire revolutions to one turn of the drive shaft.
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Rotating the one tire and then counting the rotation of the pinion will work but there are a couple of things to check. They deal with whether you have an open differential or a Limited Slip Differential. Here is a link to a website that can help:
http://www.jedi.com/obiwan/jeep/misc/gearratio.html
and I will copy some of his words of wisdom here:
So, assuming you've got an axle up in the air with the driveshaft disconnected & neither wheel on the ground:
If you turn one tire & the other one either stays still while the pinion rotates, or the other one rotates backward while the pinion stays still, or something in between, then you've got an open diff or a very weak LSD (like a Trac-Lok with too many miles on it). In this case, you need to secure one wheel (perhaps by lowering the tire onto the ground), then you can figure your gear ratio by rotating the airborne tire TWO full rotations and counting the number of times the pinion rotates. 3.73 turns means 3.73 gears. If you only rotate the tire once, then 1.865 turns means 3.73 gears.
If you turn one tire & the other one turns the same number of turns in the same direction, then you've got a good LSD or locker. In this case, you can just rotate the tires ONE full rotation and figure your gear ratio by counting the number of times your pinion rotates. 3.73 turns means 3.73 gears.
Good Luck Bryan!
Fred
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Thanks,
I just haven't checked. I'll do it this weekend.
I don't remember doing it but knowing my way of thinking... I would have confirmed that the unoriginal differential had the same ratio as the tag, while I had it out, or I wouldn't have put it in.
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Bryan, it might be best to get over to Mo's Speed Shop in Dallas http://www.mosspeedshop.com/ They have a chassis/rolling road dyno with an excellent diagnostician running it; name's Jeff. He's very good with carbs. I think it's worth the money (maybe $100 or so for an hour) to get you pointed in the right direction.
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Bryan, it might be best to get over to Mo's Speed Shop in Dallas http://www.mosspeedshop.com/ They have a chassis/rolling road dyno with an excellent diagnostician running it; name's Jeff. He's very good with carbs. I think it's worth the money (maybe $100 or so for an hour) to get you pointed in the right direction.
++1 I'll definitely do that!
Didn't know about them.
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Please keep everyone posted on what you find out!
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Will Do! I'm all wrapped up into restoring the convertible top frame right now!
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My 66 Mustang "A" code coupe, 4 speed, 3.00:1 rear axle consistently gets 18 mpg on 93 octane. I've achieved just over 19 on a couple of occasions. Don't know what I did differently to get 19, but I did get it. 20-22 with an automatic seems like a stretch.
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With gas at $4/gallon, many of us have renewed interest in fuel economy.
Although not related particularly to it's 289 big brother, there's a nice little article regarding the 200 six cylinder in Shop Tips Vol. 6 No. 10 June 1968. Author Ak Miller takes a stock 1967 6 cylinder 3-speed which he measures at 65 horsepower, and through a series of performance upgrades increases the horsepower to 100. And then runs a miles per gallon trial with an averaged 36 mpg!
Now admittedly some of his modifications aren't exactly Concours (headers and swapping carburetors), but some wouldn't be visible to a judge - Carburetor re-jetting, ignition timing, and camshaft upgrades.
Interesting reading and a good source of improvements for the six cylinder crowd - and by analogy their eight cylinder big brothers.