Alright have a 69 camaro w/ 350, M21, and 10 bolt rear (not sure of gears). Used to just cruise around town, but want it to have some get up and go.

My problem is that it seems that my top speed seems to only be about 70mph
maybe im just crazy but i would think that even my little 350 could go faster than that.

What could i change to fix this? while keeping same motor and transmission.

If you plan on using the same motor and transmission, your only other options are a larger rear tire diameter (may look silly) or new gears in your rear end.

Do you know what your current ratio is? If you topping out at about 70, I'm guessing 4.11 or 4.55 gears. Too high for highway travel. You could go all the way down to 2.73 or 3.08, but because of your M21, it may be difficult to get off the line nicely.

A good option are the mid 300 gears... 3.42, 3.55 or 3.73.

First thing though... check to see what you have.

I was going to get the ratio way for sure, and want to go with the 3.73 option. On that note my other question is that ive looked into getting a whole rear end package and the they give options for the gears you want, but none of the gears seem familiar. For instance i want the 3.73, but their closest option is 3.75; is this the same thing or different.

Also im sure wrong place for this but figure ill save myself some time. What would an upgraded ignition due for me

Alright have a 69 camaro w/ 350, M21, and 10 bolt rear (not sure of gears). Used to just cruise around town, but want it to have some get up and go.

My problem is that it seems that my top speed seems to only be about 70mph
maybe im just crazy but i would think that even my little 350 could go faster than that.

What could i change to fix this? while keeping same motor and transmission.
Is it drag limited (power) or RPM redline limited to 70 MPH?

redline limited

with a 25" tall tire, and a roughly 5000 RPM redline, 70mph at redline is probably low 5's in the axle. You got some deep gears. put the axle on jackstands, car in neutral. make a mark on the driveshaft and a mark on the tire. count how many turns it takes with the driveshaft to complete one rotatation of the tire. that's your ratio.

the only upgrade i would do to your ignition is change to an HEI to get rid of your points if you're still running a stock distributor. you said you just cruise around town, so no need to spend money on some trick ignition box. just more stuff under the hood to break. HEI or a points eliminator kit and go.

if your clutch isn't slipping and you have a tach in the car, give us a speed and what RPM you have at that speed, bet we can get pretty close to what's in the car now.

with a 25" tall tire, and a roughly 5000 RPM redline, 70mph at redline is probably low 5's in the axle. You got some deep gears. put the axle on jackstands, car in neutral. make a mark on the driveshaft and a mark on the tire. count how many turns it takes with the driveshaft to complete one rotatation of the tire. that's your ratio.


As long as he has posi that is true, now that I am typing this why would someone install 5.xx:1 gears and not have posi or spool or something, but just in case.

Once the car is up in the air, spin a tire, if the other spins the same direction then you have a posi, locker, spool, something and just follow his directions above. If the other tire spins in the opposite direction or doesn't spin then you have an open differential and need to do a little more math that described above.
Make sure only one tire spins and the other stays still. Take the number of turns of the driveshaft and divide by two that will be your rear gear ratio.

Oh, and what size rear tire are you running?

I was going to get the ratio way for sure, and want to go with the 3.73 option. On that note my other question is that ive looked into getting a whole rear end package and the they give options for the gears you want, but none of the gears seem familiar. For instance i want the 3.73, but their closest option is 3.75; is this the same thing or different.

Also im sure wrong place for this but figure ill save myself some time. What would an upgraded ignition due for me

What you have to remember is, no matter what rear gear you use, with a tranny that has a final drive ratio of 1:1, you are still going to be running high in the RPM range when you use even a 3.73 gear. The only way to get low RPM's with a 3.73 is to get an overdrive tranny(TKO-600, T-56). You are not dropping the revs that much going from a 4.10 to a 3.73 rear gear. True, you will drop it some, but not that much. Here is just an example of the RPM's you would drop using a 24 1/2" overall tire diameter. At 55mph and a 3.73 rear gear, the RPM's are 2815rpm. With a 4.10 rear gear and a 24 1/2" overall tire diameter, the RPM's are 3094rpm. Now, take that same tire diameter and 4.10 rear gear using an overdrive ratio of .64:1, your RPM's at 55mph are 1980rpm. It's the tranny's final drive ratio that is killing your highway revs and the only thing an ignition upgrade will do is make the car get to the high revs faster. It will do nothing to drop the revs. If you are hell bent on keeping the same tranny you have now, is going to a higher gear ratio(lower numerically).

I am in the same boat as you. I have a Powerglide and 4.10's. At 55mph, I am turning 3094rpm. My tranny is original, but I am going to replace it with a T-56 so I can keep my 4.10's and not kill the engine on the highway. I drive my car everyday so I need to drop the highway revs. I 100% plan on keeping the original tranny, but only put it in storage. You can do the same or you will HAVE to get higher gears.

Using the calculator I have, with a 25" tire, 70mph with a 5.08 rear gear, the RPM's are 4782rpm. With a 5.38 gear, the RPM's are 5064rpm.

How about a 26" tire and 5.88:1 Yeah! (Edit: Thats what I came up with in trying to guess his rear gears, not what I am suggesting)

But, seriously an overdrive trans is the way to go.

Imho, the best gears out there are 12-bolt 3.31's AND 10-bolt 3.36's!!

Please do yourself a favor and pull the cover and see just what you have, write down the numbers and come back and we will help you decode everything!

As for installing drag gears in a 10-bolt, DON'T THINK SO... Unless it's a later 8.5" rearend!

pdq67