Best stock et before today at 3685 pounds was 13.83 @ 98.21mph for my automatic. Today ran stock tires - trap and a 4.30 gear. Then down loaded a 87 diablo tune.
Results stock: 2.10 60' 5.82 330' 8.90 1/8th @ 80.24 13.83 @ 98.21 Old times.

Added 4.30 gear today results:2.04 5.73 8.80 @ 79.89 13.67 @ 100.93

Today added 87 diablo tune results: 2.05 8.74 80.81 13.54 @ 103.25

I learned that the converter is tight to get a good 60'. A 4.30 gear flys through 1-2-and 3rd gears before the 330' mark. RPM at 1320' is 5800 rpm. It makes 4th gear work hard but IMO waste torque and usage of the first 3 gears. Anything above a 2000 launch smokes the tires. I left at 2000 and let it roll a few feet then eased into it quickly.
I was happy to see 103.25 mph but the et does not match the mph due to converter. I ran 22.44 mph out the back door as good as most sticks.
So auto's will have a tough time to match the sticks based on the converter IMO.
I was thinking the gear alone would help the car more but not so far with my mods.

RPM at 60mph is 2450 rpm on way home.
Hope this helps some for the auto's.

 

those are still decent gains and decent results. Thanks for posting them. :drive:

 

Why the 4:30's as opposed to the 4:10's if you din't mind? I don't know about gears and I was looking to get some 4:10's. Thanks for your advice in advance.

 

I wanted to test a theory about gears in an automatic. I knew that most sticks would go with a 4.10 from 3.55. So to better equal out things(auto vs stick for my own peace of mind) I went with the 4.30. Mostly to see if the MPH gap could be closed between a stock 3.55 stick and a stock 3.31 auto. I think you will note most stock sticks ave 101 to 103 mph in the 1/4. Now we know a 4.30 gear in a auto will put you over 100 mph almost 101. I plan to go back later and try a 4.10 to make better use of the first 3 gears. After I try some other mods. You can also see that the stock converter holds these back. I want to add I have nothing but praise for the sticks :worship: . It's my own little project trying to make this auto a little faster. 4.10's would be a good deal for an auto IMO. Good Luck.

 

Good info Scott....Glad to see you're still tiinkering bro...

John

 

Good idea testing the 4.30's but are you planning on switching those to 4.10's? That's what I will be putting in next. That should help you out for sure.