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#1
03-31-2005, 06:18 AM
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The facts:
69 GTO Matching numbers 400 with Comp Camps 260 Magnum (212, 212 at 50, 440/440 lift), Q-jet, ram air exhaust manifolds, 2.5" exhaust system, stock distributor with Pertronix Turbo 400, Holeshot 2000 converter 3.55 gears How can I get better than the 10 mpg or so I get? I may switch the gears to 3.08. Anything else I could do? |
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#2
03-31-2005, 06:18 AM
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The facts:
69 GTO Matching numbers 400 with Comp Camps 260 Magnum (212, 212 at 50, 440/440 lift), Q-jet, ram air exhaust manifolds, 2.5" exhaust system, stock distributor with Pertronix Turbo 400, Holeshot 2000 converter 3.55 gears How can I get better than the 10 mpg or so I get? I may switch the gears to 3.08. Anything else I could do? |
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#3
03-31-2005, 07:07 AM
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If you go back to a mild camshaft grind
and install the higher rear end ratio you should be able to get 16 miles per gallon out of it. The only other thing that would help is transplanting an OHC 6 cylinder engine or trading it in on a Toyota. |
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#4
03-31-2005, 07:24 AM
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HPP had an article (Jan 2004) on the installation of Crane's adjustable vacuum advance, in which they picked up 1.5 mpg.
The article says engine modifications, and today's fuels, can cause the stock advance canister to not work optimally, or not at all, so you are not obtaining the optimal spark lead. Summit sells Crane kit 99601-1. Its inexpensive and may make your car run better anyway, so its worth a try. I bought the kit, but have not put it on yet. |
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#5
04-02-2005, 01:06 PM
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dont drive it, THESE are muscle cars designed to go fast, dont turn too much & hopefully stop.
GM wasnt looking for gas milage, only BEATING the competition. just my opinion
__________________
1969 Early 01D JUDGE #s MATCH RA III 4 Spd (Concours Restored) 1969 PRO STREET GTO 2500 lbs. ALL ALUMINUM 505 1969 RARE All Glass GTO (FOR SALE) YOU NEED THIS AC Cobra Kit Car 521 670 HP/715 Trq LOOKING FOR V PARTS !!!!!!!!!!!! |
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#6
04-03-2005, 11:56 AM
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I have a supercharged 428 in my GTO and my mileage went from 6 yes six mpg on the highway to 14 by installing a 200 4R overdrive trans.
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#7
04-03-2005, 08:07 PM
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All you have to do is recalibrate your odometer!
__________________
Gold Goat goes orbit orange at pontiacsonline.com |
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#8
04-04-2005, 07:47 AM
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a gto is not about gas milage,sell or trade it for a bug
__________________
home of the never ending list of pontiacs 2 69 gto converts 1 69 gto htp auto trans 1 69 gto 4 speed 1 69 gto judge 1 75 ta 1 79 formula 1 80 formula 1 81 ta 1 89 formula 1 96 ta 1 66 mustang 1 84 mustang 1 89 25th anniv mustang convert [email protected] 
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#9
04-04-2005, 07:48 AM
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i think there is a bug forem on the net
__________________
home of the never ending list of pontiacs 2 69 gto converts 1 69 gto htp auto trans 1 69 gto 4 speed 1 69 gto judge 1 75 ta 1 79 formula 1 80 formula 1 81 ta 1 89 formula 1 96 ta 1 66 mustang 1 84 mustang 1 89 25th anniv mustang convert [email protected]
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#10
04-04-2005, 02:14 PM
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My Goat runs high 10's and with OD can cruise at 2000 rpm on the highway. Mr. Nobs how about yours?
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#11
04-04-2005, 04:04 PM
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Not to sound TOO smart-ass, but inquiring minds want to know--what mileage does your 10-second Goat get, Bob W48? Better than the 10 mpg 71 T/A gets?
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#12
04-04-2005, 05:35 PM
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I get 15 mpg with my 4100 pound, 2.73 geared, 400 w/ turbo 400 62 Grand Prix and it runs 13.80@100 mph. I think you should get better then 10 mpg.
__________________
Eric 1969 GTO - 461, turbo 400, Continental 13", 3.08 gears. - 12.59 e.t. @ 108.43 mph, 1.898 60' 1978 Oldsmobile Cutlass Supreme- 461, turbo 350, PTC 3500 converter, 9" 3:50 gears. = 11.39 e.t. @ 117.55 mph, 1.599 60' on E85 |
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#13
04-04-2005, 07:14 PM
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I got a 66 caddy, 429 that will get 13-14 on the highway!
__________________
"My ol' man is a television repairman...he has an ultimate set of tools!....I can fix it..." J. Spicholi |
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#14
04-04-2005, 07:34 PM
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Pontiac6269,
You have 2.73 gears while my GTO runs 3.55s. There's the difference. I think I'll be swapping to 3.08s as that's the lowest I can go with my 12 bolt's 3 series carrier. |
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#15
04-05-2005, 12:09 PM
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While you change to the 3.08 make sure you take up the advice to swap the th400 for the tr2004r overdrive trans , due to the shorter first and sec gear, your car with the 3.08 will acselerate as fast as a th400 with a 3.73 rear ratio . 3e is 1on1, 4 is 0.67 , so you have your stoplight funn AND you highway crusing milage and top end speed with it , nouw ask yourself wat will be the smart thing to do!!!!
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#16
04-05-2005, 02:22 PM
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Let's see, a TH400 has a low of 2.42, so the overall low in front of a 3.73 is 9.03, while a TH2004R will have an overall low of 10.25 with a final of 2.5, but one with a 3.08 rear will have a low ratio of 8.47 and a final ratio of 2.06, right? Figuring on spending most of the time in third or OD, it sounds like it would be more fun to swap the trans and leave the rear alone! A lot more responsive.
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#17
04-05-2005, 04:19 PM
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Kind of a oxymoron. MPG and GTO. Try this, push it around, you'll get great mileage with it that way.
Seriously, get a overdrive and a really tall gear. Good luck.
__________________
Should you ever find yourself the victim of others peoples bitterness, smallness or insecurities, just remember, things could be worse. You could be them. Check out my sons blog, www.driftundertheradar.com  |
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#18
04-05-2005, 10:49 PM
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<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Shadowjack:
Let's see, a TH400 has a low of 2.42, so the overall low in front of a 3.73 is 9.03, while a TH2004R will have an overall low of 10.25 with a final of 2.5, but one with a 3.08 rear will have a low ratio of 8.47 and a final ratio of 2.06, right? Figuring on spending most of the time in third or OD, it sounds like it would be more fun to swap the trans and leave the rear alone! A lot more responsive. </div></BLOCKQUOTE>............Eather way 3.08 / 3.55 its a win win situation . i got 3.42 with the od trans . due to the high perf engine , i will have serius traktion problems as first and sec gear will act like 4.11 / 4.56 . thing is he didnt askt for FUNN ,but more mpg!! , but yes your right trany swap alone will dubbel the funn lololol |
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#19
04-06-2005, 05:52 PM
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Shadowjack if you look at my original post I said it gets 14mpg on the highway. I have no idea what it gets around town but its not good.
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#20
04-06-2005, 08:04 PM
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Man, I have the TH400 and Iam changing my 2.93 Rear to a 3.55 posi as we speak...costing me $900...did I make a mistake? I can still change my mind.
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