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What gears to go with out back


robs70monte

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Well im going threw my Monte 8.2 10 bolt i haven't taken it apart yet so i don't know what gears are it but i know its not a posi and its make some loud noises i have a posi carrier and some 3:31 gears they any good for this combo?,Its a mildly built 350 .30 over flat tops camel back heads,268h comp cams cam, performer intake and a holly 680cfm,headers with glass packs and a th350 with a shift kit stock converter. that all i can think of for now let me know if i forgot any thing i plan on dragging the car this year and i hope to run some ware in the 13s

Any help is appreciated

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Not sure exactly what you are asking. If the car came with a 350 SB, it likely has 2.73 gears. By comparison, 3.31 gears usually came with the 454 and should give you better acceleration, better ETs, but less top end speed and less gas mileage. There are web sites that can give you anticipated performance based on the specs you have.

 

I'm not an expert, if you need more you need to get some of the drag guys to comment on this. Dave? Bill?

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I'm not a rear end guy myself either,... well at least when it comes to cars, but I would say that it depends on what you want. I like the 2.73 because it gives me good gas mileage on the highway and sufficient acceleration, but if you want to go from stoplight to stoplight as fast as possible, I would say the higher ratio is what you want.

 

Hopefully one of the drag guys will speak up at some point.

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ask CRAZY DAVE.....he will help his chevelle launches real good if you have read his past threads...331's for highway driving hands down, for strip and top end stuff 373 or 411's...

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I debated the same thing a couple years ago when I did my 12 bolt. I had bought a set of 3.31's from e-bay but one of my friends convinced me to go with 3.55's. I'm glad I did the 3.55 these are big heavy cars.

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Rob,

 

I don't know what your plans are regarding rear tires, but they will also affect your car's performance (i.e. acceleration, speed, mileage) because your OVERALL drive ratio includes the gear ratios of your tranmission, the "rear end" ratio AND the size (diameter or height) of your rear tires.

 

Here's a very useful web site if you want to see the performance results of changing any or all of these factors:

 

http://vexer.com/automotive-tools/speed-rpm-calculator

 

You will first have to edit the axle ratios (i.e. change 3.23 to 3.31), select "automatic transmission", edit the transmission gear ratios (i.e. 2.52 for 1st and 1.52 for 2nd in a TH350) and edit the vehicle weight (I used 3850). Then edit your tire profile or height and torque converter efficiency.

 

Now select a forward gear (1, 2 or Drive) and move the throttle slider up to the rpm limit you plan to set (watch the digital displays not the gauge needles). It will show you the mph (for that rpm), your predicted quarter mile ET and Speed and even give you a required horsepower estimate for that set up! I had to play with it awhile to get it set up but it very helpful once you figure it out.

 

Whether you choose a 3.31 or a 3.55, you could run a taller tire on the street for more efficient cruising and a shorter tire on the strip for beter launch and acceleration. It's a common practice, of course.

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Some of the 350/2barrel cars came w/10 bolt BOP(Buick/Olds/Pontiac) rears right from the factory. Make sure you know exacly what you have 1st. I redid my BOP w/ 3:55s. It was a little pricey but I heard that theyre real strong and it helped get my old 355ci into the 12's. Either way a gear change is going to feel like you gained 100HP and put a nice smile on your face....Enjoy!! Al

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Your only choices for your BOP are Richmond 3:55/3:90/4:11, and I think Motion makes a 3:75 now. The Eaton posi unit is Pricey @ around $550 but its for 3-4 series gears so if you ever wanted to go more radical in the future you could just throw 411's in there. The Ring and pinion is around $250, plus another $100 for the install kit and another $200 for the install. Just a heads up.

 

 

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I'm going to get the summit catalog out tonight and order up some gears ect.. Im going to get some eagle h beam rods and some speed pro .125 dome pistons and light weight vlaves for the camal backs figure while I have the motor out do it up agin but better this time around

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I would try to come up with a honest plan as to what you expect to get out of your monte. .125 dome pistons really pumps up the compression on a small block. H beam rods are great, I run them myself you will need to get the assembly balanced. Lots of 350s have cast cranks including our montes. H beam rods are overkill on a cast crank. There are a lot better heads out there now than the camel back heads I would consider that before putting a lot of cash into a head that has limited capabilities as compared to more effective heads.

I am not trying to put a damper on your party but I want you to be happy with it when you are done.

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I see you are selling a set of vortec heads in the for sale section. They are a whole lot better than the heads that you have on the motor and you don't need dome pistons

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I dis like the center bolt valve covers and I don't have a vortech intake I have a set of camal back heads I might try also but for now I want to see what I can do with the 882s if I don't like them ill go with the camal back heads

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