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Author Topic: Low end Power?  (Read 5708 times)

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Offline AMCLOVER258

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Low end Power?
« on: June 20, 2014, 03:30:01 PM »
So i am New to the Eagle family. I have an 82 $ door with the 258. On the highway the car runs amazing i can keep steady at 85 90 with no problem however i have 0 take off... that car will not even Chirp a tire. is that normal lol?
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Offline eaglefreek

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Re: Low end Power?
« Reply #1 on: June 20, 2014, 04:10:10 PM »
Quote from: AMCLOVER258 on June 20, 2014, 03:30:01 PM
So i am New to the Eagle family. I have an 82 $ door with the 258. On the highway the car runs amazing i can keep steady at 85 90 with no problem however i have 0 take off... that car will not even Chirp a tire. is that normal lol?
Yes, it is quite normal. I assume you have and auto transmission and would bet you have 2.35 gearing in your axles which don't help at low speeds. Also, the stock 258 camshaft is too "mild".
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Offline AMCLOVER258

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Re: Low end Power?
« Reply #2 on: June 20, 2014, 06:20:49 PM »
 >:( Darn.. So a new cam and all that lovely head stuff would help get'r moving a little more?
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Offline Mernsy

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Re: Low end Power?
« Reply #3 on: June 20, 2014, 06:25:50 PM »
Is your tranny shifting gears early by any chance?
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Offline AMCLOVER258

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Re: Low end Power?
« Reply #4 on: June 20, 2014, 07:47:27 PM »
NO, it is weak though, it doesn't shift very smoothly.. like even if i put it in 1st gear( its a 3 spd auto with the OD) it takes off a little better but wont turn those tires!
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Offline Mernsy

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Re: Low end Power?
« Reply #5 on: June 20, 2014, 08:23:26 PM »
The 4.0l head and cam swap will turn them.
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Offline carnuck

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Re: Low end Power?
« Reply #6 on: June 21, 2014, 11:47:43 PM »
No overdrive unless it was swapped in. Just a lockup converter. Swapping to 2.72 ratio will help you a lot and STILL give good freeway performance. Taller than stock tires kill the power too, because it actually CHANGES the effective gear ratio. Low profile tires will give you take off power again.
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Offline AMCLOVER258

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Re: Low end Power?
« Reply #7 on: June 23, 2014, 04:35:24 PM »
So 2.72 Ring and pinion and find someone to put it in.. i dont think i could go Low prof's that would look rediculous lol
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Offline Mernsy

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Re: Low end Power?
« Reply #8 on: June 23, 2014, 04:57:34 PM »
Quote from: AMCLOVER258 on June 23, 2014, 04:35:24 PM
So 2.72 Ring and pinion and find someone to put it in..

You have to change gears in both diffs.
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Offline BenM

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Re: Low end Power?
« Reply #9 on: June 23, 2014, 06:00:58 PM »
With the 2.35 gears it's like having a four-speed transmission that will only start in second. The lockup will definitely feel like another gear, it's more noticeable with 2.35 gears.

Back in the old days you really had to suffer, I have a Pontiac with an ST-300 (another GM two-speed transmission mostly unrelated to the famous Powerglide) and a rear around 2.9. It is positively glacial until you got the thing up over 40, even with a V8. I guess the point of that is even with the wide-ratio automatic you should have it could be worse.  ;)

With the '82 you probably have a better chance of being able to swap the front gears for a 2.72 set, and the 2.72 with the wide-ratio lockup transmission is a pretty good compromise, 3.08s in a sedan or wagon are a good choice as well, it depends on if you do more highway miles or not. There are a couple of threads here that discuss the things you have to look for to see if your front end can be changed, not all 2.35 gears can.

Play around at http://www.grimmjeeper.com/gears.html and you'll see the RPM to speed. The "Dodge TF 999" has the correct wide-ratio gears. To see the difference with the narrow transmission used in 80 and 81, first is 2.45 and second is 1.45. For fun, my two speed ST-300 is 1.77 in low. These are all 1:1 in high, but they slip and act like a lower gear if they don't lock up, the calculator does a nice job of compensating for that as well.
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Offline Eagle Groupie

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Re: Low end Power?
« Reply #10 on: June 23, 2014, 07:03:03 PM »
Quote from: AMCLOVER258 on June 23, 2014, 04:35:24 PM
i dont think i could go Low prof's that would look rediculous lol

Time for some Photoshop! :)
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Offline carnuck

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Re: Low end Power?
« Reply #11 on: June 24, 2014, 01:13:04 AM »
If you plan taller tires, 3.08 is far better and leaves room for O/D down the road. I'm surprised no-one has taken me up on the  2.72 vacuum front diff (70K miles and rarely in 4x4) and Model 20 with 2.72 gears for $100 for the pair.
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Offline Baskinator

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Re: Low end Power?
« Reply #12 on: September 15, 2014, 08:47:20 AM »
Quote from: carnuck on June 24, 2014, 01:13:04 AM
I'm surprised no-one has taken me up on the  2.72 vacuum front diff (70K miles and rarely in 4x4) and Model 20 with 2.72 gears for $100 for the pair.

I probably would if I wasn't on the opposite coast :/
« Last Edit: September 15, 2014, 08:47:51 AM by Baskinator »
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Offline carnuck

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Re: Low end Power?
« Reply #13 on: September 15, 2014, 12:52:39 PM »
That's always the way! I know of a wagon for parts in Spokane, WA that will be crusher bound (if not already done)
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Offline IRON HORSE

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Re: Low end Power?
« Reply #14 on: September 15, 2014, 05:06:04 PM »
    Hello, Is your vacuum advance working ??? if it's not working you won't have power during accleration, but will cruse OK. Another thing to check is the kickdown linkage from throttle to transmission. This boosts the trans pressure when you step on the gas, and lowers the pressure when your stopped and in gear. If this linkage fails in the low pressure position the trans will slip and eventually fail.  Just my two cents .... Later, Iron Horse  :o
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