1970 CUDA 440

[1970CUDAAAR]

Hi!

Please provide me comments on the following 4 issues that I have with my CUDA:

1) NOISY REAR-END
I have a 3:23 ratio differiential which is noisy when I accelerate the vehicle. I tried some special oil which is supposed to illiminate or redcuce the noise. The noise has recuce a bit but not enough for me - it is still somehow annoying to me when I drive it. Should I replace the differential. I'm also considering moving to a 3:55 ratio. Will this increase the RPM too much?

2) COMPRESSION RATIO - ENGINE

We did a compresssion on the engine and it give 10 to 10 on all cylinders. I checked with a friend that does racing and he told me that I dont need to worry in my case as my CUDA is essentialy a street machine. Some machanic told me that I need to ajust the varves.

3) I have the following cam set up:
CAM : COM21-223-4 "Comp BB Mopar Extreme Energy Cam"
LIFTERS : COM867-16 "Comp Cam Lifters Hydraulic BBM
TIMING SET : COM2104 "Timing Set Double Roller Comp BB Mopar"

With this set up do I need to increase my STALL to eg. 2,500 or 3,000 to make it more punchy when I push the gaz full trottle?

4) I find the car to be too noisy when I drive it = noise comming from the body or road. I'm thinking of addind some barrier between the floor trunk or else to recuce the noise - I saw some stuff on Year One which is supose to resuce the moise - SUGGESTIONS PLEASE

Thanks a million!

 

[pschlosser]

Hi!

Please provide me comments on the following 4 issues that I have with my CUDA:

1) NOISY REAR-END

2) COMPRESSION RATIO - ENGINE

3) I have the following cam set up:

4) I find the car to be too noisy when I drive it

1. Rear End - The noise is likely something mechanical. It could be wear, a bearing, a U-joint, it may be something else. Those noises can be a challenge to pinpoint. I would not expect a magical oil, special or not, to make much of a difference. In my experience, when the differential is wearing out, it seems noisier on deceleration, not acceleration. That said, the differential can take lots and lots of abuse before it fails. I've driven some cars with very noisy rear-ends for long periods without much issue. Just make sure it has the correct amount of oil in the differential, and it may last for another 10 years or more.

As for the ratio, a higher ratio does indeed translate more torque to the wheels, and 3.55 is kind of the next step from 3.23. The higher ratio you go, the less friendly the car becomes to highway and long-distance driving. For those living in dense population areas, when they rarely drive their cars on freeways, the higher ratio is not an issue. Keep in mind, if your tires don't "hook up" and grip at 3.23, it's possible a higher ratio won't make things significantly better. Perhaps, with the addition of a sure-grip differential, wider and softer (they don't last as long) tires can help.

2. Compression - if the compression is pretty even and consistent across all cylinders, that is something you can be proud of. Many of us on engines with 100K+ miles don't see this, yet still enjoy some street performance and turning people's heads.

Most Mopar V-8 engines use hydraulic lifters (unless the engine has upgraded to a different type, like a roller lifter) and so, there isn't a periodic adjustment needed to the valve. If compression is low due to valve wear, adjustment won't correct this. If you hear lots of valve noise, when the engine is idling, then this is something to investigate further.

3. Camshaft - Your specs are not too far from the factory 440 High Performance specs, so I would expect similar behavior to OEM. The OEM 440 HP has a great deal of torque in the lower end, so I'm not sure a higher stall convertor will make significant difference, compared to the changes you'll see in casual drivability.

4. Noise - These cars ARE noisy. To some, that is part of their charm. They are not like the modern, rubber-frame-mounted, highly-engineered modern copies of the vintage muscle car. Road noise transmitted to the frame is not easy to block out with deadeners, because the entire frame and car become the speaker. That said, many restorers add (peal and stick butyl foil) material to the interior to help mitigate noise and to minimize (header-radiated) heat. Improving the types of tires, and suspension bushings will probably do more to reduce noise than adding insulation.

Other things, such as a wearing differential, U-joints, glass-pack exhaust, and noisy air filter can contribute to the noise, overall. But for the most part, these are noisy cars and that often equates to lesser weight and higher performance.

The well-tuned 440 HP, even with factory specs, is an amazing performant engine. And in these relatively light vehicles, such as the E-body, coupled with their legacy suspension and engineering, they are a thrill, possibly even scary, to drive. Investigate to make sure what you have now, is running in top condition. Sometimes, overlooked issues and resulting performance loss, lead us to believe we need a change and more $$$ spent rather than research, testing and repair.

 

[Xcudame]

I agree with @pschlosser, the rear end noise might be something other than the rear axle gears. Check the U-joints. Going from 3.23 to 3.55 gears will increase rpm by 10%. Not sure what you mean by compression 10 to 10, but what you want is all cylinders bring close to one another. Actually a leak down check is a better indicator of engine health in my opinion. The camshaft will be fine with your torque converter. Although the 110° lobe separation is great. Howard Cams are a better choice, but you got what you got. These cars are 50+ years old! Get a nice stereo and crank up your favorite tunes. This will help with the noisy rear gear if it is the gears!