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Old 08-15-2002, 11:56 AM
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Question Cam, gears, convertor and weight???

Hey All.
With getting ready to build my Hemi motor later this year, I was wondering, how actually does Gearing, car weight and Convertors equal your decision on cam selection?
My gremlin with me in it will weigh around 2800 lbs and I have a 2 speed powerglide and 4.56 gears. Im thinking about dropping my gears to a more cruisable 4.10 or 3.73 and getting a 2500-3200 stahl convertor.
I figure with my Hemi's 375 -425 horses and 500 ft lbs of tourque I wont need a ton of deep gearing.
Im thinking about going a cam with around 470-480 lift, 280 degrees of duration and about 224-230 at 050.
Do you think this combo of cam will be alright with my gearing, convertor choice? Also, my redline with my Hemi will be around 5500 rpm's and if it matters I'll be running a low profile 2X4 intakw with small AFB carbs. HG

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Old 08-15-2002, 12:39 PM
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You definitely won't like the 4:56s! I would go with 3:54s on the street but the 3:73s are ok if you don't want to look too wussey with high gears. I run 3:23s in my 354 hemi (set up similar to yours), 3000# Willys and am very happy with them, but I never race it either. With 28" rear tires, I cruise at 60mph, 2000RPM. If I had 4:56s my engine would be turning over 2800rpm - too noisy to listen to my Spark-O-Matic!

Be careful on the converter - just get the stall that you need to idle without stalling out all the time. This is a place where more is not better. Too loose and it will kill mileage and generate too much heat on the street. My first guess is that a 2000 converter would be better suited to your car on the street.
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Old 08-15-2002, 12:55 PM
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Stall speed is directly related to the amount of torque your engine produces-the more torque, the higher the stall speed. For example, a converter with a 2,800 to 3,200rpm rating might provide approximately 2,800rpm of stall speed behind a mild small block V8, but about 5,000rpm behind a big block making 800-plus ft-lbs. of torque. While most converter manufactures list stall speed ranges, those numbers are very, very general guidelines; true stall speed is impossible to measure do to vehicle variables.
You definately don't want to overshoot your stall speed. High stall converters are mainly to allow high-idle big cam engines to not stall or load up and to launch into there power band. Try and stay conservative like willys said unless you're only seeing track. A trans temp gauge is a must. Personally I wouldn't go too crazy on the gears either. That's a lot of engine with good low rpm power to launch. Go enough to make her snap but keep it drivable. Willys right on the money.
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Old 08-15-2002, 06:20 PM
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Hemmi,gears will relate to cam shaft cause of rpm range,you want to keep your rpms usable.Too much cam not enough gear you won't see peak power till extremely high speeds,also you'll proably do your driving befor the power band.To much gear not enough cam will result in a car that leaves the light like an animal yet winds out early.
Car weight can also factor in that you need less torque to launch it.In whih case you could compansate for a low compression ratio.Running a bigger cam can result in less low end torque.But with a light car you can get away cause you don't have no weight to launch.
Converter is there to comensate for higher idle qualitys of bigger cams.Also the bigger the cam the higher the RPM range Ex.1000-3500(stk) to 3500-7500(big) a converter can allow you to launch in or closer to your RPM range(which is where you make the power)
Also compression is important.
224-230@050 would probably be good w/3.73-4.10.As long as you ain't got little short tires.
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Old 08-16-2002, 06:56 AM
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I forgot the tire size on here. Im running 31 inch by 18.5 inch Mickey Thompsons. Thas why I thought 4.10-3.73 somewhere. HG
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Old 08-16-2002, 07:31 AM
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Send me your email address and I'll send you a graph I made that shows engine RPM resulting from speed,ratio,tire size. The you can make an informed decision.
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