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My MPG is poor |
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1967AmericanSW
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Joined: Feb/10/2008 Location: Arizona Status: Offline Points: 317 |
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Posted: Apr/30/2008 at 8:49am |
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TIres: 195/75R14
Ignition set to 4 BTC Engine appears to be OK, no smoke on cold starts, nothing. Agree about high highways speeds being an issue on this car; I (probably) have 3:15 gears which would explain the definite motor revving at speeds much past 60 MPH, etc. Let me 'futz' with the timing, alignment, etc. and go from there. Thank you everyone for your tips |
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tyrodtom
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Joined: Sep/14/2007 Location: Virginia Status: Offline Points: 2869 |
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Posted: May/01/2008 at 7:11am |
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I not sure most people realize why automatic transmissions hurt mileage, besides the little bit of slippage you'll always have in the non lock-up auto, they've all got hydraulic pumps in them, thats what powers the hydraulic servos that control the bands in the trans. I've seen a chart of how much hp the various automatic transmissions consume, the lowest was around 15-20 for the Powerglide, to over 40 hp for the 450 Turbohydramatic, and 727mopar. It didn't have the more modern lock-up autos on the list, they would be a little better, but they still have the hydraulic pump also.
When I first got the 74 Hornet I was talking about it was a auto. , a 2.7? rear end, I drove it about 2 months that way, it got around 15-18 mpg, I put the 4 spd from a wrecked 79 Spirit, also the disk brakes and electronic ignition from it, all at the same time, it jumped to a easy 20 . How much was due to the transmission change and how much due to the ignition there's no way to know. The rest of the mileage gain was due to the 2 bbl manifold and the valve job, gasket match, and very careful tuneing. The super-tune I was talking about took over 2 weeks. But the final results were worth it to me.
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66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.
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billd
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Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 22784 |
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Posted: May/01/2008 at 7:27am |
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You make some good points. Hydraulic pumps need power. It's the same reason on a lawn tractor with the hydrastatic drive they recommend adding 2 hp to your requirements.
e.g. I go in and say I need 20 hp to mow my grass due to grass type, slopes, etc. for hydrastatic drive, they say bump that to 22.
It's more for a car........ and when you are only talking a couple hundred ponies anyway for a 6 (or less?) it's a chunk you don't want to part with.
Conveniences and luxuries cost - either $$ or power. (or both)
In my wife's case, it's a must, she's restricted, so there's no choice. But I'll drive anything that moves.
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purple72Gremlin
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Charter Member Joined: Jul/01/2007 Location: Illinois Status: Online Points: 10096 |
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Posted: May/03/2008 at 12:12am |
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Thikstik
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Joined: Mar/20/2008 Location: Alabama Status: Offline Points: 1121 |
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Posted: Sep/10/2008 at 3:34am |
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I would go for more timing....set it until ping , then back off. Also, make sure vac advance is working.
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75 gremlin x, jeep 4L headed 258,Clifford 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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biscuit
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Joined: Sep/10/2007 Status: Offline Points: 27 |
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Posted: Sep/10/2008 at 7:18pm |
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You could put on a 4.0 head and fuel injection.
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purple72Gremlin
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Charter Member Joined: Jul/01/2007 Location: Illinois Status: Online Points: 10096 |
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Posted: Sep/10/2008 at 7:23pm |
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poormansMACHINE
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Charter Member Joined: Jun/28/2007 Location: Shoemaker-Levy9 Status: Offline Points: 12357 |
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Posted: Sep/10/2008 at 7:32pm |
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Yup........and people dont do the math right either.....[/QUOTE] Hey hey, I can count to 21. |
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purple72Gremlin
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Charter Member Joined: Jul/01/2007 Location: Illinois Status: Online Points: 10096 |
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Posted: Sep/10/2008 at 7:36pm |
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Hey hey, I can count to 21. [/QUOTE] Did not mean you PMM |
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matt167
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Joined: Apr/01/2008 Location: New York Status: Offline Points: 1439 |
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Posted: Sep/10/2008 at 7:45pm |
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my '65 196, with BW automatic, gets 19 MPG and it's well worn. this is highway
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