Does a C-4 need an aftermarket converter with a stock GT roller cam?

[kyle67]

I have 1.7 roller rockers on the car. It is fully tuned and runs well, just still has a little shake to it, most notable at idle. Anybody else seen this?

 

[joesgt281]

Regarding your subject question, I'd say no.
I had a C4 w/stock convertor behind a 351 with roller cam (moderately wild) and 1.7 rockers and it ran great.

 

[2ndgen]

I have 1.7 roller rockers on the car. It is fully tuned and runs well, just still has a little shake to it, most notable at idle. Anybody else seen this?

Hmm... a looser converter will not do anything about your shake at idle; not clear if that is what you are interested in addressing or if you just mention it to describe your cam...

The best things you can do for ANY C4 is a transgo shift kit and an auxiliary cooler.

That said, even though you may not NEED a looser converter, you might benefit from one depending upon your engine, rear gearing, and goals. If you get your car dyno'ed and look at it's power curve, it will be pretty obvious where your ideal stall speed should be. The stall speed of a converter is often misunderstood...

It is not the case that the car won't move until you hit the stall speed... I run a 3500 stall speed and can leave a stop light at 1200 RPM.
It is the case that below the stall speed a good torque converter actually multiplies (increases) your torque! Doing so does generate more heat, so with a loose converter ALWAYS run an auxilary cooler.

So if your engine really comes into it's own at about 2800 RPM, a 2500-3000 stall speed converter will allow your engine to reach the power band quickly when you floor it and also improve your torque where you need it most.

Where does gearing come in? Below the stall speed the torque multiplication is generating heat... so if the gearing on your car is such that at freeway speeds you are still under the stall RPM, you will be generating extra heat and getting less gas milage.

For mildly modified engines, I consider 3.25 rear gears and a 2400-2800 RPM stall speed to be the most fun combination. This is a generalization; far more information about your engine and goals would be needed to pick a converter.

I also highly recommend Andre at Edge racing converters, he will build you a custom converter for not much more than your typical B&M or TCI, and there are worlds of difference in performance. Andre will want to know a lot of details about your engine/cam/gears/goals before making a recommendation.

Good luck,
-Rory

 

[kyle67]

Thanks! I was actually thinking of going with a mild converter and some 3.25s with a posi in the 8 inch. I have a factory 5.0 with 95 cobra heads, and the roller rockers I mentioned. The cam is stock 95 GT. I am running a performer intake with a Edelbrock 500 cfm carb. It runs well, just not what I would consider to be a fast car.

 

[Starfury]

A torque converter and gears would really wake that car up. You've got more than enough power to scoot along.