[johnv805]

I have a camaro with a 327 ci 300 hp engine, 3.55 posi rear end, and a TKO 600 (.64). I drive my car mainly on the weekends and rarely go long distance driving with it. I want more acceleration so I am thinking of upgrading to a 3.73 gear ratio. Is that ideal or should I go higher.

[Eric Kammerer]

What size rear tire do you run?

Just based on your 1st ratio and rear ratio now, you are over 10:1 multiplication, which is pretty optimal for a street car.

http://www.chevyhiperformance.com/te...ing/index.html

With a 327/300, I am going to go out on a limb and suggest that the rear axle ratio is not the most limiting factor on off the line acceleration.

[rojo]

I doubt you would notice the difference, it's only 5%. The 3.55 or 3.73 is a great choice with the 2.87 TKO600 first gear. I'd spend my money on the engine.

[johnv805]

I'm currently running 225/60R15 and maybe considering changing to 275/60R15. If the 3.55 is a great choice then I might just spend money on the engine.

[idoxlr8]

With the 255's I would stay with the 3.55 gears, Even with the 275's your gears and the 1st gear of the 600 are enough to roast the tires at will. Traction is the limiting factor.

[68RS-SS]

I've currently got the TKO600 .64 OD and 3.73s. It's truly a nice combo but in my opinion what you have is slightly more ideal. There's times when I'd like a tad more out of my gears. I have a 12-bolt with series 4 carrier so can't go down any more otherwise I'd be happy to trade. My wheels are 17" and probably a little taller then what you currently have or similar to what you're planning on. I'd leave it alone and enjoy it.

[SIDEWAYS]

Originally Posted by johnv805

I have a camaro with a 327 ci 300 hp engine, 3.55 posi rear end, and a TKO 600 (.64). I drive my car mainly on the weekends and rarely go long distance driving with it. I want more acceleration so I am thinking of upgrading to a 3.73 gear ratio. Is that ideal or should I go higher.

With a 327 and a .64 od, and the fact that you rarley go on long distances, you would be MUCH better off with the .82 OD unit and a 3.55-4.11 rear. You will never end up being able to use 5th gear. I have a 509, TKO600 .64, and 3.90's...and 5th is still too tall for what I do, unless I'm on the highway. Will likely end up with a TKO w/.82 OD and change the gear to 3.55.

[Steiner]

Originally Posted by johnv805

I'm currently running 225/60R15 and maybe considering changing to 275/60R15. If the 3.55 is a great choice then I might just spend money on the engine.

If you go to a 275/60 your acceleration is only going to get worse. The tire is going to get taller which is the same as going to a numerically lower gear, almost like going to a 3.23. The calculator says if you put a 275/60 on you would need to go to a 3.73 just to get back to where you are now.

I think a 4.11 would put you where you want to be with your current tire size given that you rarely do any highway driving. Gears are probably the cheapest thing at this point unless you want to spend the money on engine work. If you're thinking about gears you ought to spend $50 to do a dyno run to find out where your power band is than set your gears up to be fun where you do 95% of your driving.

Play with the calculator:
http://www.keislerauto.com/speed_analyzers.php?sa=gm_5

[Vegas69]

Originally Posted by SIDEWAYS

With a 327 and a .64 od, and the fact that you rarley go on long distances, you would be MUCH better off with the .82 OD unit and a 3.55-4.11 rear. You will never end up being able to use 5th gear. I have a 509, TKO600 .64, and 3.90's...and 5th is still too tall for what I do, unless I'm on the highway. Will likely end up with a TKO w/.82 OD and change the gear to 3.55.

How is that going to help his acceleration problem? I disagree with you. In anything other than a race enviroment, the .64 gear is perfect for crusing at 80 around 2500 rpm with a 3.73. One of my favorites when I'm not racing.

I do agree that a little lower rear gear would help that little engine. I don't think swapping from a 3.55 to 3.73 is going to make you happy though. More power is what you need.

[Eric Kammerer]

Originally Posted by SIDEWAYS

With a 327 and a .64 od, and the fact that you rarley go on long distances, you would be MUCH better off with the .82 OD unit and a 3.55-4.11 rear. You will never end up being able to use 5th gear. I have a 509, TKO600 .64, and 3.90's...and 5th is still too tall for what I do, unless I'm on the highway. Will likely end up with a TKO w/.82 OD and change the gear to 3.55.

Vince, keep in touch if you decide to change to the TKO600RR (0.82 OD). That is what I bought because that was what was available in 2004, and my mild 402 seems like it might like the 0.64 5th. I don't know when/if I will be recovered enough from my accident to be able to swap trannys, but if you wanted to change to the 600RR, maybe we could work something out.

I am just out west in Downingtown, so you can't be too far from me.

[SIDEWAYS]

Originally Posted by Vegas69

How is that going to help his acceleration problem? I disagree with you. In anything other than a race enviroment, the .64 gear is perfect for crusing at 80 around 2500 rpm with a 3.73. One of my favorites when I'm not racing.

I do agree that a little lower rear gear would help that little engine. I don't think swapping from a 3.55 to 3.73 is going to make you happy though. More power is what you need.

As far as acelerating, and given he want maybe a 275/60/15 tire, I think a 4.11 is what I would go with, maybe even deeper being its a 327. But the fact that he RARELY see's the highway, I just think the .82 is a better choice, b/c now you have a 5th gear that you can use around town and on the back roads. The .64 is apprx a 1000 rpm drop from 4th to 5th, and not all motors will like that AROUND TOWN. Right now, my motor screams in 4th, but lugs in 5th. On the highway...different story, you can run whatever gear you like. Depends on what your intentions are.

I ran my TKO 600 .64 with a 3.31 rear and couldnt use 5th unless I was doing 65 min, and it really liked 75. I have 3.90's now, and still cant really use 5th around town/backroads - my primary type of driving. Highway - feels like I could use 3.42 or even higher though.

He may have the trans already, so its a mute point. I wish they would make an OD trans with a .7x OD ratio. But keep in mind, a 4.11 gear becomes a 3.37 with the .82 OD, and 2.63 with the .64. You really need to know how your motor runs at various rpms before making decisions about transes and rear gears IMO.

[68Lemans blue]

.64 and 3.73's with 225/60-15 nice and happy here...... Happy motoring

[johnv805]

I drive my car to work about once a week which is a 12 mile commute and when I use it on the weekends the longest I will drive it will be 15 miles. I never race my car on the tracks. I don't want my 1st gear to run out quick. Here are my engine specs.

327 ci 210hp
Edelbrock Head Gaskets (Compressed Thickness 0.038 in.)
Flat top pistons
Compression Ratio 8.75:1
Bored out 0.02 over
Pertronix Ignitor II Electronic Ignition
Flame Thrower II Coil
MSD-6AL Ignition Control Box
Edelbrock Performer Air-Gap 2601 Intake Manifold
Edelbrock Thunder Series 1806 Carburetor (650 CFM)
Edelbrock Performer 60759 Aluminum Cylinder Heads (70cc Chamber, 185cc Intake Runner, 2.02 Intake, 1.6 Exhaust)
Edelbrock Performer-Plus Hydraulic Roller 2208 Camshaft (Duration 280/290, Lift .462/.479)
Full Length 4-into-1 Hedman Hedders
Flowmaster Dual Exhaust with 40 Series Delta Flow Mufflers

[TMessick]

IF you decide to change your rear gears, I'd go to 4.10's -- I don't think the change from 3.55 to 3.73 will be significant enough for you to really feel it much.

As far as the comments about the usability of the 0.64 5th gear, I guess I'm special since I found 5th usable behind my 307 even with 2.73 rear gears. It wasn't exactly a rocket ship in 5th, but would run down the road OK at 55mph. Of course my engine was mildly cam'd and carb'd and ran a lot of spark down low to keep things running smooooth. If your engine doesn't like low RPM, you can end up with issues with the wider 4/5 spacing... (Finally changed over to 3.73's now, but am still working through re-bleeding the brakes and getting it back on the road).

From your above description, I think I'd spend some $ on cylinder heads 1st. With the 70cc chambers and 8.75 compression, you're losing some torque and efficiency. Cam is a bit mild (212/222 at 0.050" if I'm reading the specs right) and probably won't like to rev too high, but should play decent on a street motor. Maybe go a step bigger if you're OK losing some bottom end to pick up higher RPM power...

[johnv805]

What cylinder heads and cam would you recommend?