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 Post subject: 4.30 gear????
 Post Posted: Mon Dec 01, 2008 8:36 pm 
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Joined: Wed Nov 19, 2008 12:02 pm
Posts: 36
Location: Alabama
I need more help!!! O:)  I got one of those "ebay deals" on a nodular strange center section for my 9inch that had a 4.30 gear already installed. My question is should I stick with it or what? This is my first big HP, big tire car and I need some advise on the gear size.

Heres what I have so far:   434 sb chevy(not even in the truck yet), 400 trans with a brake, 4500 stall converter, 32-14 tire.  Not sure of the weight yet est. around 3000 lbs.


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 Post Posted: Mon Dec 01, 2008 8:40 pm 
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Joined: Wed Nov 19, 2008 12:02 pm
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Location: Alabama
I have 2 tracks within equal distance from me one is 1/8 and the other is 1/4. I'm sure the 400 will do better on the 1/4 but I'm curious if anyone has run one on an 1/8 mile track.

Wanted to go with the glide but funds are gettin low and the 400 was just sitting there so i figured I would give it a go.


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 Post Posted: Mon Dec 01, 2008 9:19 pm 
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Location: Florida
Stick with it, the 434 makes a bunch of torque, the 400 just adds to it. Short shift the 1-2 and you should gain a little ET.


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 Post Posted: Mon Dec 01, 2008 9:46 pm 
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My 3500lb 55 Studebaker with a pump gas 434 went 10.0s @ 135 at Rockingham Super Chevy back around 1999 in street trim with a 33x15x15 inch DOT M/T tire, a 5:13 gear and a PowerGlide.  Ran that same combo in the eight mile and best it ran was high 6.40s @ 106 or so.

At "The Rock" the engine was turning about 7700 at the finish line and I don't remember what it was doing in the eight mile but that gear was a little too low for a quarter and a little too high for an eight.  For eight mile only I probably would have gone with a 5:57 and for quarter mile a 4:88 would have been about right.  

With your tire being a little short a 4:56 might be about right but hey, if you already got that 4:30 why not use it until you use it up, especially since you got that way low gear in that turbo.

FYI, building a decent Glide isn't that expensive depending on what you have to give for a useable one to begin with.  If you decide to try one then don't fool with anything less than a 1:76 planetary cuz you'll be wasting your time and money if you try to run a 1:82 behind that engine.  If you need help with one of those, then there's about 4 of us here that build our own that can help out and Ron Owens or Matt Summers can provide you with parts at a decent price.  Just yell if you need help!

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 Post Posted: Mon Dec 01, 2008 9:48 pm 
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I'd prefer the P/G, but the 400 will certainly work fine if built right and worth using if you already have it. If you don't have a trans-brake for it yet, I'd go with a glide before investing any more money in the 400.

As far as gear ratio, it depends on the power and rpm range of the engine. With a 4.30 gear at 6500 rpm (using 5% converter slip) the speed would be 137mph. Will it make enough power to go 137mph in the 1/4? Does it need more rpm than 6500? or less? Mid 10's would normally be 125mph in the 1/4, 137 mph is well into the 9's.

For best ET you need more gear. If keeping rpm down for longevity and less maint is important, stick with the 4.30.

Rick


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 Post Posted: Mon Dec 01, 2008 10:19 pm 
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What kind of HP is your 434 making?  I run a 434,  glide , 32" tire and 4.57 gears.  3050lbs I run high 9.50's and 6.00's in the 1/8th.  1/4 mile rpm is 7500 and 5500 stall.    Matt

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 Post Posted: Mon Dec 01, 2008 10:25 pm 
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Joined: Wed Nov 19, 2008 12:02 pm
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Location: Alabama
Yeah the trans is in the shop getting a brake right now so that money is already spent.  As far as the engine, the guy who did my machine work (he's pretty reputable around here) estimated over 600 hp so i'm thinkin the power will be there.

Thanks for the info Ken. I'll keep you guys in mind if and when I  go to the glide.


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 Post Posted: Tue Dec 02, 2008 7:14 am 
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get the book from hp written by Carl monroe about power glides very good book with all the tricks and how toos of a racing glide and it also explains how it works =;

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 Post subject: Re: 4.30 gear????
 Post Posted: Tue Dec 09, 2008 3:02 pm 
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dun2run wrote:
My question is should I stick with it or what?

That depends on your goals, and use of the truck.

If lowest et is all that matters, and traction isn't a problem, you'll need a lower gear. Drag cars need more gear, and converter, for best ET, than most think they do.

For lowest et, the engine needs to be out of breath at the finish line. For some engines, badly out of breath.

I'd run what you have, look at finish line rpm, then decide if you want to turn more rpm. If so you'll know how much more gear to give it.

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