Switching to 4.30 gears

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nathan 73 dart

nathan 73 dart

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I recently foung a set of 4.30 center section for sale with a suregrip. My car Has a 440 with eddy heads balanced looking to top out somewhere near 6000 rpm. It has 28" tall mickey thompson drag radials with 3.55 gears. I'm curious if this would be to much gear and what others experiences have been with them.
 
nathan 73 dart said:
I recently foung a set of 4.30 center section for sale with a suregrip. My car Has a 440 with eddy heads balanced looking to top out somewhere near 6000 rpm. It has 28" tall mickey thompson drag radials with 3.55 gears. I'm curious if this would be to much gear and what others experiences have been with them.
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Someone has a calculator to figure it out.....

Chime in if you know where to find it or a link!
 
Here's a link to an interactive calculator.

http://vexer.com/68rt/speed.html

When you say you want it to top out at 6000 rpm when do you want that? In the 1/8th mile or 1/4 mile? If your running 1/8th mile the 4.30's will work good for you. If your running 1/4 mile their probably a little steep unless the engine is built pretty stout.

If your just talking top speed either should top out at 6000 rpm. It's just that with 3.55's you'll be running about 133 mph at 6k and the 430 gears will be running about 111 at that speed.

BTW: If your running an automatic there's an adjustment called "torque converter efficient". Every torque converter varies but a 95% setting will get you close.
 
nathan 73 dart said:
I recently foung a set of 4.30 center section for sale with a suregrip. My car Has a 440 with eddy heads balanced looking to top out somewhere near 6000 rpm. It has 28" tall mickey thompson drag radials with 3.55 gears. I'm curious if this would be to much gear and what others experiences have been with them.
Click to expand...

I think with a 28" tire, you'll be happier with 4.10s, you will see better then 6k through the 1/4 mile, even with 4.10s & a 28" tire, i would run a 29" tire with 4.30s for a 440 if it was me.
 
Thanks for the info the motor has been built up some. I'm just not sure how high I can safely rev up the motor. I'm thinking with the 4.30 gears I would be in the 6500 range on the 1/4 at the end. Is that to many rpm's for a balanced 440.
 
................430s will b perfect with a 28in tire.............kim.........p/s u r supposed 2 gear 1o% over redline...........
 
Im going to a 4.30 also but i want a 30in tire for1/4 mile and hopefully ill shed alot of weight off the car and its a 440.
 
We have changed from 3.91posi to a 4.30 spool with a 26" tall tire have not run it yet. Sounds like I will be looking for a taller tire.
 
nathan 73 dart said:
I recently foung a set of 4.30 center section for sale with a suregrip. My car Has a 440 with eddy heads balanced looking to top out somewhere near 6000 rpm. It has 28" tall mickey thompson drag radials with 3.55 gears. I'm curious if this would be to much gear and what others experiences have been with them.
Click to expand...

It should be fine, one of my friends ran 4.30's in his 451 Dart with 275/60 radials for years and they worked good in the 1/4 when he had a hyd cam, when he switched to a solid he went to a 29x11.5 to keep the RPM's in range, it was running 98-99mph in the 1/8, 117-118mph in the 1/4.
 
Hey do you want to sell the 3.55s ? are they a posi 489 case 8 3/4?
 
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