What gear?

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75dartsport

75dartsport

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Ok since I found out today that I currently have a 3.55 gear and not the 3.91 I thought I had.. Help me out. My car is a 1970 duster. Full interior so probably around 3200lbs. 360 284/484 mopar cam. 750 holley. 727 with 3500 stall. Had it at the track 3 weeks ago ran a best of 8.23 I think. Never used 3rd gear shifting at 5800rpm. Was running out of fuel in second about 5300. I fixed the fuel problem and ran a 8.15 last week. Still didn't use 3rd gear. Thought I had a 3.91 gear but turned out to be a 3.55. How much would a gear help me out on times? I'm running a 28" tall tire. What gear should I run. It will only be for the track every now and then. Otherwise it'll have the 3.55 in it. Any help is appreciated and if you need any more info let me know. I have access to a 4.30 and a 4.56, but if it really isn't going to help much then I'll leave the 3.55 in it. I really like the 3.55 on the highway it cruises nice at 70mph.
 
3.91 or 4.10 is going to be the best street/strip gear...

next time...look at a 904 trans with a 2.74/1.54 gear set.....
 
I probably needed to add that when at the strip it will be 1/8th mile only. Most all the tracks around here are 1/8th mile.
 
For the 1/8 I would try the 4.56. I had a 360 with a similar cam and it slowed down anytime I shifted above 5000-5300. I think you might gain some with lower shift points but I don't know what the rest of your combo is.
 
Personally, I think the gear you have sounds great. A steep gear on the street just plain sucks. You can have just as much fun with your 355's at the strip, you still have to have a good reaction time and run on your index,(very exiting and tricky stuff). Tell you the truth, the 320's in my challenger seem kinda steep with my 10" converter. Now, if you had a overdrive transmission....
 
Seeing you want the best of both street and strip,get yourself some smaller tires for the strip.Maybe some 26 inch if your not into swaping gears every time you go racing.Just a thought..
 
I tried different shift points as low as 5200 and it ran its best times at 5800. As far as the gear I don't mind changing it. It will be a strip gear only not a street gear. Just want the gear that will produce the best times with my combo.
 
4:56s for sure, there is just nothing like the pull of the steep gears, short tracks like steep gears, I ran 4:88 with 28" tire for 1/8th mile. Its all in your 60' so ya the gears will help you, plus it keeps your rpm in your power range on shifts. its a win win.
 
I know its hard to tell. But if I go from a 3.55 to a 4.56 what kind of time improvements could I expect as long as it still hooks up?
 
Was hoping to get a little more input before going with a gear
 
My vote is to go with what most everyone else says----4:56 or 4:88s BUT i'd get a seperate pumpkin & set it up with a spool & only use it for the track.
Now if you plan on a solid/roller lifter cam later on or perhaps a motor that you plan to "buzz" higher, you can, naturally, go toeven higher gears......
 
Somebody already mentioned the gear calculator...
Unless you want to swap center sections just for the occasional trip to the track (seems to be a bit much to me), How about a set 14" wheels for the back. You're running some kind of DOT tire now, right? Mickey Thompson has a set of 235/60-14s, that are 25" diameter, and I'm sure sticky enough. That's fully lowering your gearing by more than 10%, bringing your rollout from almost 88" to 78 1/2". IIRC, your gearing will be real close to 3.91 w/28" tire, with less mass to get moving!
Me, I'm kinda lazy, I'd rather just swap my wheels and tires.
(although at some point my quest for quick will lead to bigger #'s than my 3.55s)

Again, just another opinion,
Tom
 
I have 391 in challey and was going to put in 355s wanna trade
 
No, I love the 3.55 for cruising. Thanks for the offer though.
 
Ok guys I,m going with the 4.56 any guesses on what kind of increase in times I can expect?
 
71beater said:
Scampman408...PM sent
Click to expand...
x2!



75dartsport said:
It will only be for the track every now and then. Otherwise it'll have the 3.55 in it.
Click to expand...
I don't mean to sound rude, so I hope I do not come off that way.
Since you obviously like driving the car with the 3.55:1 gears in it why even bother changing gears for limited track outings?
Why not just maximize the car with the 3.55:1 gears that are in it?
Sure stiff gears will get you a better numbers at the track, but if your car can only get those bragging rights numbers with a 'track set-up' what's the point?
 
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