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That's the million dollar question. To let you all know what's going on my dad & I are building the pickup into a monster HP street machine. Here's what's going on. We are dropping a 351 Windsor & stroking it out to be a 408, using AFR 205 Heads, Victor jr Intake Manifold, 770 Holley Street Avenger Carb, Crane Cam that's 244/255 @ .050", getting rid of the 3 speed manual & throwing in a C4 Automatic. The question is what stall should I use. I'm half ass thinking of at least a 4,000 stall but not sure. Have no clue as to what size gears. I've been told that 4.56 gears would be the best. Just want ya'll to know this will be driven on the street so I want most of the power in the 3000 to 6000 rpm range. Any help will be greatly appreaciated
 

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Indo-Canuck-Yankee
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Well, first of all, it ain't no Mustang so I have no idea why you're posting on this forum. To answer your question however, sounds like a ridiculous combination for the street daily driver, you'll need a tranny tougher than a C4, and good luck driving it.
 

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Once the motor is completed, get it on an engine dyno. This will tell you where it makes peak torque (rpm) and where it makes peak HP. That will tell you what stall converter you need. You want the car to launch at peak torque, that's what gets it moving. Unless the motor is built to spin to about 7K, I would most likely go 4.11's. The C4 is no problem. I would look up JPT in Eaton Falls, Michigan. 1000 HP with one of their C4's is no problem. Also remember a torque converters stall is not fixed. Lets say at some point you ad N2O...it will stall higher.

Ron

As a added benefit, the engine dyno will also tell you if your carb is big enough.
 

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gears/stall

ok you have a decent starting poing point,
by posting engine specs, except you forgot one,
the vehicle weight
find out what it is then you can decide stall and
gear, the more weight you have the tighter the
convertor you choose
if you weigh over 3500lbs
then it would be wise to drop 10 degrees duration
on the cam, build some trq down lower to heave
the boat, 408 is good for all types of power,
if you weigh more than 4200lbs then then
205 heads might be hurting you...

post the weight then a choice could be
chosen easier

dont cheat and look up the weight on the title
take it to the local packing house, or somewhere
 
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