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Author
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Topic: Soggy bottom end
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Dubz
Gearhead Posts: 1890
From: Manitoba Canada
Registered: Oct 2002
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posted 08-10-2005 03:34 PM
   
now that i've been driving it for a good while, i've noticed some problems with the car, the bottom end has little to nothing, under 30mph it has hardly any power at all, but above that it starts to SCREAM, it's great on the upper end, but the bottom is severly lacking. At first i thought it was the transmission kickdown, but when shifting manually it still has little under 30mph.Now i'm wondering if it's just the highway gears being the problem, or if i should look somewhere else. 30mph with 26" tall tires, and in first (2.46) would be 2500rpm, and that may just be too low to make decent tq to move this heavy car. Also wondering if it's maybe tuning, either carb or timing related...lighter secondary springs to come in sooner, or re-curve the distributor (running about 15 inital, 38 total) vaccum advance disconnected, not sure when it's all in by as i don't have a tach in the car as of yet. Also wondering if it's just a mis-match of parts, as the plan hasn't come together for exhaust, and gears, so the intake and carb are probably not doing so well. Engine for those who don't know it's
74 351W stock bottom end & cam
stock exhaust
RPM air gap intake
1" 4 hole carb spacer
1.7 rockers
Holley 670cfm vac sec
C6 tranny w stock convertor
9" with 2.75 gears
all in a Gran Torino weighing an est 3600lbs.
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66-408-stang
Journeyman Posts: 60
From: lafayette, in usa
Registered: Nov 2000
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posted 08-10-2005 04:36 PM
Stock heads? The stock cam should produce real good torque right off idle. Try more intital advance and then a weaker spring to bring it in sooner up to the point that you get ping then back off just a little. Then the carb may need some tuning - how do the plugs look? With stock exhaust you may need to richen it up a lot. Steeper rear gears would be great but I ran a similar combo and found these things to make a basically stock 351w to run great considering how stock it was and in a heavy car. BTW, as the motor makes more torque right off idle you will see the converter stall at higher rpm, just what you want.
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66-408-stang
Journeyman Posts: 60
From: lafayette, in usa
Registered: Nov 2000
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posted 08-10-2005 04:44 PM
BTW, I actually lost off idle torque when I tried a 4-hole spacer on my rpm intake. Obviously, an open one is hugely flat off idle! Get that sucker above 3500 and it was a different story. I tried back and forth street driving in dis-belief that the 4-holer would reduce off-idle torque. Tried different jetting and idle feed restrictions but could never justify its use.
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Dubz
Gearhead Posts: 1890
From: Manitoba Canada
Registered: Oct 2002
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posted 08-10-2005 04:49 PM
I was thinking of trying to run without it, but i'd need a spacer of some kind as the fuel inlets can't get past the vaccum fitting in the intake otherwise. Might just try to find a plug for the intake to see if that's the problem.[This message has been edited by Dubz (edited 08-10-2005).]
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68 Coop
Gearhead Posts: 2911
From: Mesquite, NV. 89027 M&M# 4256
Registered: Oct 2004
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posted 08-10-2005 05:06 PM
I bought my spacer at the Zone, which has an insert to make it a 4 hole. Got it for $25 or so I think.------------------
William
68 Coupe
289
Edelbrock 600
Performer Intake
Headers/X-pipe/Flowmaster 30's
C4
8"rear/2:79gears
"Restomod in Progress" Good friends are hard to find, even harder to leave, and impossible to forget.
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grego37
Gearhead Posts: 365
From: los angeles,CA,USA
Registered: May 2004
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posted 08-10-2005 05:54 PM
throw a set of 3.50's in the rear, that will wake it up.
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Dubz
Gearhead Posts: 1890
From: Manitoba Canada
Registered: Oct 2002
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posted 08-10-2005 06:12 PM
I have a used set of FoMoCo 3.56 gears in the garage, but i'm not sure i am technically educated enough to tackle setup of a gear set myself.and i was hoping that i'd get a used 28 spline trac lock before i did the swap so i only have to do one setup, and save one setup kit, and or paying someone to do it one of the times. If all it is, is gears, i can live with it till i get the trac lock. [This message has been edited by Dubz (edited 08-10-2005).]
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grego37
Gearhead Posts: 365
From: los angeles,CA,USA
Registered: May 2004
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posted 08-10-2005 06:16 PM
Its worth paying someone to do it.
There is skill and experience involved.
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