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Is my converter too tight?
I am building a 406 SBC that's going in a 69 Camaro.It has AFR 195 heads ,10:1 compression 4:10 rears Th350 trans. Comp Cam 294s.I have a 3200 RPM stall in it now. Do i need to order a JEGS 3800?I can hold the car back with the brakes till about 2500 RPM's with the 3200 stall.
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If you are running a dual plane intake manifold, your converter stall is just about right for a 400 with that cam.. You cannot evaluate the true stall speed of a converter by trying to load it up against the brakes. (especialy with street tires) The engine will always overpower the brakes well before the converter maxes out.
If you want to know the real stall speed, get some racing slicks and look at the tach reading right at launch ater a good burn out to heat the slicks. As long as the tire do not spin, that is the real stall speed. Another way to see the real stall speed is to drive slowly in "D" allowing the trans to shift normally. As soon as it shifts to 3rd, mash the brakes and gas hard at the same time, The tach will monentairly flash to the true converter stall speed, just before the trans auto downshifts. Do not do this repeatly without letting the trans and converter cool, by driving the car easy at say 50+mph to cool the converter and trans. Different ashfaults will give different tire traction. Concrete is usually the best. Torque converters are generally "rated" for stall behind a typical 350ci motor. Your 400 makes more torque than a 350 so your actual maximim stall speed (with good traction) will be a little higher than 3200 rpm. Probabily around 3400-3500 with slicks and a proper ignition curve and carb set up. That cam will need a very agressive spark curve with lots of inital at idle to maximise low end torque and throttle response. I have a similar 400SBC with a B&M "3600" stall and it actually a little too much. Actual stall is about 3800-4000rpm behind this 406CI motor. It was spot on 3600 behind a 350ci motor. Get some good tires and try the 3200stall first. Last edited by F-BIRD'88; 03-15-2008 at 12:20 PM. |
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