Built 273, what sure grip ratio with a A833 3.09 first gear

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It's a big drop all righty, but it occurs at a slower roadspeed than if you had a 2.66.
Example with 3.55s and 27s;
6000 in 2.66 low is 51mph,and in second it's 4330
but in 3.09,it's only 44mph and in second its 3730.
With the 3.09, you get into second a bit sooner, that's all; and if it's still spinning........ it makes no difference.
But I guess you could always take 3.09 first to 7000/51 mph, and then second will be the same, dropping in at 4330.

But say you went with 3.91s. Well you'd probably want to short-shift first, soz you'd have something to pull from in second.
For instance, again with 27s, you could out-shift first at 5500@ 37mph and get into second at 3410. Ohhhhhhh , that big 286cam might not like that,lol . But the car is sitting at 37mph, so I think she'll get over it lol. There is a lot less wind-resistance at 37 compared to at 44, or especially at 51, so that leaves more power to accelerate.
I ran 4.30s x 3.09 for a bit with a 360 and that was nuts, cuz the 360 wound those up in a heartbeat. 3.91s were better, and for me 3.55s are just right.... for a 360 with a 230@.050cam.

One problem I often see, is when cruising in traffic at 32mph, which might be 2700rpm with 3.55s and 27s. That big 286 cam is not gonna like trying to pull from 2700 if you feel the urge to nail it. So on the downshift into 3.09, the Rs will climb to 4360, and away you go. But the deal is you had to downshift.
But there is no good gear, for a 273 with a 286 cam, to pull away in second. Even 4.30s will only increase the second-gear Rs at 32 mph..to 3280rpm.
So IMO, I would gear it for a good blast off from 32 mph,in 3.09 low, with whatever gears it takes to make me smile. ....... and with 3.55s that is 4360 with 27s.....which looks pretty good to me,lol.
And let the rest be what it will be. It's a streeter; it's gonna have other problems, chief if which is traction.
If you don't care about 32 mph, then work it out for whatever speed you do care about.
Myself, I like to be at or just over, the powerpeak, when I hit about 60/65 mph in second gear. And the magic number is 3.61s.... rounds to 3.55s. But my cam is a 276 advertised.........and so;Your power peak will be considerably higher.For you, I see 3.91s in your future....... and overdrive. 3.91s would get you 60=5800 in 2nd........and in 4th, 60=3030..... A GVOD would drop that to 2365.
Yeah the starter-gear is racy at 12.08, but so is your cam.If you find traction, that 12.08 is gonna come in real handy. And that starter gear makes it so you can practically just dump it and go, when you're behaving yourself........which is gonna be like 95% of the time........after the novelty wears off..... The novelty of buying tires twice a summer and getting imprudent driving tickets,and nobody wants to ride with you anymore,etc.... Even your son suddenly has homework all the time...................lol
You'll love it, I know I did,lol. But yeah traction will be the big deal.
 
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stroker402 said:
I agree ! I have a pair g78x14 26" tall, Snow tires I'm going to install this spring and see how they hook . heard rumors that snow tires hook fairly well on the street or track. They have been in my basement for 50 years and still look like new , nice and soft still. should be interesting. I just want to burn m up !
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G's eh? I haven't seen those since about 71/72. They didn't hook on my 1970 340 Swinger340/4speed/3.55......... That car went 98@3310#, in the qtr which,is 245hp, IIRC.That was 1971.
 
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AJ/FormS said:
It's a big drop all righty, but it occurs at a slower roadspeed than if you had a 2.66.
Example with 3.55s and 27s
6000 in 2.66 is 51mph,and in second it's 4330
but in 3.09,it's only 44, and in second its 3730.
With the 3.09, you get into second a bit sooner, that's all; and if it's still spinning........ it makes no difference.
But I guess you could always take 3.09 first to 7000/51 mph, and then second will be the same.

But say you went with 3.91s. Well you'd probably want to short-shift first, soz you'd have something to pull from in second.
For instance, again with 27s, you could out-shift first at 5500@ 37mph and get into second at 3410. Ohhhhhhh , that big 286cam might not like that,lol . But the car is sitting at 37mph, so I think she'll get over it lol. There is a lot less wind-resistance at 37 compared to at 44, or especially at 51, so that leaves more power to accelerate.
I ran 4.30s x 3.09 for a bit with a 360 and that was nuts, cuz the 360 wound those up in a heartbeat. 3.91s were better, and for me 3.55s are just right.... for a 360 with a 230@.050cam.

One problem I often see, is when cruising in traffic at 32mph, which might be 2700rpm with 3.55s and 27s. That big 286 cam is not gonna like trying to pull from 2700 if you feel the urge to nail it. So on the downshift into 3.09, the Rs will climb to 4360, and away you go. But the deal is you had to downshift.
But there is no good gear, for a 273 with a 286 cam, to pull away in second. Even 4.30s will only increase the second-gear Rs at 32 mph..to 3280rpm.
So IMO, I would gear it for a good blast off from 32 mph,in 3.09 low, with whatever gears it takes to make me smile. ....... and with 3.55s that is 4360 with 27s.....which looks pretty good to me,lol.
And let the rest be what it will be. It's a streeter; it's gonna have other problems, chief if which is traction.
If you don't care about 32 mph, then work it out for whatever speed you do care about.
Myself, I like to be at or just over, the powerpeak, when I hit about 60/65 mph in second gear. And the magic number is 3.61s.... rounds to 3.55s. But my cam is a 276 advertised.........and so;Your power peak will be considerably higher.For you, I see 3.91s in your future....... and overdrive. 3.91s would get you 60=5800 in 2nd........and in 4th, 60=3030..... A GVOD would drop that to 2365.
Yeah the starter-gear is racy at 12.08, but so is your cam.
You'll love it, I know I did,lol. But yeah traction will be the big deal.
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Ya, what he said! :poke:
 
273 said:
Hows the streetable is that cam?
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At least the way I have the 273 dialed in , I think the cam is very streetable . It doesn't buck , cruises real nice at 35 mph in forth gear. It sounds NASTY ! And all the power I want from a little 273 . I don't have any issues with it at all , as you can here in the videos .
 
stroker402 said:
At least the way I have the 273 dialed in , I think the cam is very streetable . It doesn't buck , cruises real nice at 35 mph in forth gear. And all the power I want from a 273 . I don't have any issues with it at all , as you can here in the videos .
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Thats what I thought, your about the 5th 273 guy on here running a 280 + cam and all say they work reasonably well for the size. Ones even got a tunnel ram :) Thanks

Kind of wish my valiant still had its 273.
 
273 said:
Thats what I thought, your about the 5th 273 guy on here running a 280 + cam and all say they work reasonably well for the size. Ones even got a tunnel ram :) Thanks

Kind of wish my valiant still had its 273.
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Come on over, I think I got a 65 here somewhere. We'll have to search through the sheds to to find all the parts tho, lol.
When I got it ,"It was a low-mileage ,complete running engine"lol.
Or I could sell you a nice teener
Or a 340
Or a real engine, a 360
lol.
I'll take rear quarters in trade, for a 68 fb Barracuda., and trunk extensions.
Don't hesitate, jump in the truck right now. It's bound to fly out the door in less than oh say another 20 years,lol. I've only had it since about 74...............
I got a good used 340 cam for it somewhere too. and some J-heads. A Weiand Xcellerator and I bet I could find a carb for it too.
I bet you could dingle-ball it and go racing.
 
stroker402 said:
65 barracuda formula S streeter built 300 hp 273
9.5 compression 920 heads
ld340 intake manifold intake ports matched to heads
holley dp 650
1 5/8 semi fender well hooker headers
2.5 head pipes to flowmasters,
a A833 4 speed 3.09 low first gear
3.55 rear gears
Erson solid cam short dur. high lift. 510 lift , 286 duration advertised , 2000-7000 rpm range
72*overlap. Pretty snotty cam for a 273 teener. built similar to the 66 d-dart or 65 golden commando's barracuda "gold fish" specs .
Question is :
would there be any advantage going to a 3.91-4.10 rear gear ratio.
The starter gear with the present 3.55 ratio is 10.9 . 26" tall tire being used . I have to shift pretty quick with a 3.55 gear already. 4.10 would be Really be quick and has no advantage IMO . I'd like to take it on the freeways with 26" tall tires . It's not a race car by any means .
what are your opinions ?
video of 273 with open headers www.youtube.com/edit?o=U&video_id=Lur52zZxN9Y
Thanks .
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Your link just opens my U tube page and your car is no where in site.
 
AJ/FormS said:
Come on over, I think I got a 65 here somewhere. We'll have to search through the sheds to to find all the parts tho, lol.
When I got it ,"It was a low-mileage ,complete running engine"lol.
Or I could sell you a nice teener
Or a 340
Or a real engine, a 360
lol.
I'll take rear quarters in trade, for a 68 fb Barracuda., and trunk extensions.
Don't hesitate, jump in the truck right now. It's bound to fly out the door in less than oh say another 20 years,lol. I've only had it since about 74...............
I got a good used 340 cam for it somewhere too. and some J-heads. A Weiand Xcellerator and I bet I could find a carb for it too.
I bet you could dingle-ball it and go racing.
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Car already came with a 380 hp create engine with less than 5000 miles on it.
 
I have something similar using a low first gear Aussie 4 speed (1st: 3.32:1; 2nd: 2.00:1; 3rd: 1.43:1; 4th: 1.00:1), 318 engine in a light weight car (3 series BMW), mostly used to road course track days, going from 3.45 in the rear to 3.15 made a huge difference in overall driveability, mostly working 2nd and 3rd gears on the track. Runs mid 14's on the strip.
 
HardVG said:
I have something similar using a low first gear Aussie 4 speed (1st: 3.32:1; 2nd: 2.00:1; 3rd: 1.43:1; 4th: 1.00:1), 318 engine in a light weight car (3 series BMW), mostly used to road course track days, going from 3.45 in the rear to 3.15 made a huge difference in overall driveability, mostly working 2nd and 3rd gears on the track. Runs mid 14's on the strip.
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Those are pretty nice splits; 60-71.5-70.
 
well As I mentioned earlier in the posts , I have the snow tires mounted now G78x14 like Brand new , But they are a little taller that I thought. They are 27" tall soooooooo , what do you guys recommend now for a rear gear. I was going to stay with my 3.55's that are in there now but I came across a sure grip 4.10 . Thinking about that ratio since I knocked alot off with the taller snow tire .

snow tires.jpg


snow tire size.jpg
 
run it with those old tall tires and the 3.55 gears, that will give u an idea about those who have suggested less rear gear like 3.23. snow tires may seem to be soft, but they put less rubber to the pavement. and ancient tires will not last long. your initial post asked about what advantage to changing rear gears-but you did not say what u are looking for - more revs, more gas mileage, quicker acceleration, what. stick with the 3.55 gears and go play with as wide a tire as possible
 
For a streeter; Run as much rear gear as you dare with that engine, as that's the only way to keep it on the pipe.
Imagine your powerband is from 5000 to 6500, about 1500
With 3.55s and 27"tires;you will be on the pipe from 37 to 48, 59 to77, 81 to105,and 113 to147.
With 4.10s, you will be in the zone.................. from;32 to 42, 51 to 66, 70 to 91,and 98 to 127
With 4.56s.......................................................from;29 to 37, 46 to 60, 63 to82, and 88 to115
>Now look at the numbers in the mph-window from zero to 60 mph.
With 3.55s you're in the zone for 13mph.With 4.10s it's 19mph. with 4.56s it's 22mph
The more time in the zone, without tirespin, the quicker you will be.
>Also look at how fast you need to be going to find the zone.
With 3.55s it's 37mph, with 4.10s its 32mph,and with 4.56s just 29mph
The sooner you get into the zone, the sooner you start shaving time.
> also look at the 65mph cruise rpm.With 3.55s; 65= 2867, 4.10s are 3311, 4.56s are 3682,...
>or what can 2850 get you? 65 w/3.55s, 56 w/4.10s, and 51 w/4.56s
>look at hammer-down at 32 mph in second gear, my favorite.
This will be; 2710 with 3.55s,3130 with 4.10s, 3480 with 4.56s...If you can't break the tires loose at these rpms;you'll need to put a little toe on the clutch, downshift, or get some skinnier tires lol. Downshifting at 32 mph into first will get you 4360/5040/5600 well wudja lookit that, the 4.10s at 5040,are right on target.
I also say this, cuz with that cam and just 9.5 Scr, she's bound to be soft on take-off. the 4.10s will help with that, but you might have to slip the clutch some until the power comes on. The solid lifter spec was a smart choice , IMO,otherwise you'd probably be yanking that stick .
 
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Marcohotrod said:
run it with those old tall tires and the 3.55 gears, that will give u an idea about those who have suggested less rear gear like 3.23. snow tires may seem to be soft, but they put less rubber to the pavement. and ancient tires will not last long. your initial post asked about what advantage to changing rear gears-but you did not say what u are looking for - more revs, more gas mileage, quicker acceleration, what. stick with the 3.55 gears and go play with as wide a tire as possible
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Fuel economy is not an issue , since it's only driven for a few months out of the year . I'm not worried out burning up the snow tires . I'm not drag racing the cuda but I'm looking for quicker acceleration . I may occasionally jump on the freeway heading to a car show ( maybe a few miles) , If I stay at 55mph with the 27" tall tires I don't think the engine will be screaming that bad with 4.10 gears . Just thinking 3.55 gears and 27" tire , the cuda will be a dog all around. I like going fast ! lol I use to drag race a 65 dart convertible with a mag crate 402 stroker that ran 11.3 on the motor. 10.9s on the bottle.

raggie 5-11 driveway Gooddddddddd.jpg
 
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I like the 4.10 gear with 27" tall tires for overall street / strip. I'm just out to have fun with this classic 273 cuda . that's what it's all about .
 
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