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  #61  
Old 04-02-2013, 12:16 PM
carpoor carpoor is offline
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John, I would not worry about that. Where do you shift the car at? Even if you trapped 120 MPH - you would only be around 6,000 RPM at the stripe. I have 3.73's in my car, and will be on a 26.5" tall tire. I expect around 106-109 MPH, and have a low RPM big block. I did the math, and I should be right where I need to be when it crosses the stripe. For best possible ET, you always want to be about 200-400 RPM past the RPM where you make peak power.

Don't give it a second thought, go have fun!
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  #62  
Old 04-03-2013, 10:53 AM
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what transmission do you have? Honestly with automatic I have not paid attention to the shift point under high acceleration.
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  #63  
Old 04-03-2013, 11:55 AM
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Muncie 4 speed, my 4th is the same 1:1 ratio as 3rd gear in your TH350.

Do you have a tachometer? I would experiment manually shifting it. See where it likes it, the ETs will show you where that is. Take a pen and a small note book with you. Record shift points, launch RPM & technique, tire pressure, etc.

When I sold my 2000 Z28, I gave the buyer a note book to dummy proof driving the car. It had shock settings, launch RPM, staging technique, tire pressure settings, and how to adjust them for track conditions. I had the car dialed in pretty well. My ETs generally never varied more than a few hundreths of a second.
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1972 SS 454 Chevelle LS5/M21/12 bolt 3.73 posi
1969 Malibu COPO L72/M20/12 bolt 3.31 posi
1968 Malibu LQ9/4L80E/12 bolt 3.73 posi
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  #64  
Old 04-04-2013, 12:11 PM
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yeah got a tach. Talk to me about launch rpm?
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  #65  
Old 04-04-2013, 05:41 PM
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What tires do you have? Size? What do you know about the torque converter?

All of that will affect how the car leaves. I got my best 60' times with the Z28 by bringing the RPMs up to 2500-2600 while holding the brake, then going wide open on the third yellow. Any lower, and the car left soft. If running a street tire, I don't recommend that method. On street tires, I always take a little bit of slack out of the driveline. Then on the 3rd yellow, let off the brake and roll the throttle to the floor as quickly as the tires will allow.
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1972 SS 454 Chevelle LS5/M21/12 bolt 3.73 posi
1969 Malibu COPO L72/M20/12 bolt 3.31 posi
1968 Malibu LQ9/4L80E/12 bolt 3.73 posi
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  #66  
Old 04-05-2013, 07:36 AM
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I took some time to read up on torque converters and now have a much better understanding of how they work. The torque converter I have is a Hole Shot 3200. Although wide, my tires are street but I don't have size off top of my head. I also now understand why my 406 runs on the hot side. I didn't realize the higher the stall, the higher the temps run in the transmission.
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  #67  
Old 04-05-2013, 01:35 PM
carpoor carpoor is offline
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John, do you have a transmission cooler on it? Also, 400's have siamesed bores with steam holes. They don't have the exact same cooling passages as the rest of the early SBC engine family. They tend to run a little warmer. Also, things like DCR, cam overlap, etc - will affect engine temps. Hell, even the size of the exhaust system will somewhat dictate how warm an engine runs.

Based on what you've told me, I would load the converter a little bit at the line. On the third yellow, pop the brake and let it roll forward, then roll the throttle to the floor. (DON'T JUST MASH IT UNLESS YOU WANT TO DO A STARTING LINE BURNOUT) See where it shifts just leaving it in D. If it shifts low and falls on it's face, experiment shifting at different RPMs.
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1972 SS 454 Chevelle LS5/M21/12 bolt 3.73 posi
1969 Malibu COPO L72/M20/12 bolt 3.31 posi
1968 Malibu LQ9/4L80E/12 bolt 3.73 posi
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  #68  
Old 04-05-2013, 06:56 PM
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I would look into the trans cooler for sure. Carpoor was right when he talked about the many factors that can dictate the engine temp. I know that the trans cooler helped me a lot.
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  #69  
Old 04-06-2013, 09:58 AM
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Something else I want to suggest since you will be on street tires, race with a full tank of gas. I even go one step further, I remove the valve stem in the spare tire. Then using some small tubing hooked to an old washer pump, I fill my spare with water. It adds weight to the right part of the car.

There are other tricks like trimming down the bump stops on the upper control arms. It will give you more suspension travel. (I went one step further and completely removed mine)

I am dedicated to making my car hook on a limited tire. (Reproduction Good Year poly glass G60-15s)
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1972 SS 454 Chevelle LS5/M21/12 bolt 3.73 posi
1969 Malibu COPO L72/M20/12 bolt 3.31 posi
1968 Malibu LQ9/4L80E/12 bolt 3.73 posi
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  #70  
Old 04-11-2013, 01:18 PM
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Yes it does have a heavy duty trans cooler but original radiator. The previous owner did the build up. The converter is a B&M 3000 stall not 3200. I thought I'd call the owner and ask him what times he got. He did say without good racing tires you can't really launch using the converter or it will just sit an spin. Your suggestion to roll the throttle carefully without breaking loose would be my best bet.
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