I was wondering if someone could tell me where my power bands peak at. I have a 428 with ported heads, CJ valves, headman headers, performer RPM intake, 2" carb spacer, 770 holley, Hydraulic flat tappet Comp cam, .513/.520 lift, 262/270 duration, 110 lobe seperation. It is in a 76 F250 4x4 w/C6.
The reson I am trying to find out is, I just rebuilt the trans and installed an ACC stall convertor that was suppose to be 3000 stall. But now that I have it together it is stalling around 4200! And my shift point has been increased to 5500. My thinking was if the power band is aroung the 4200 mark, I will need to return the stall for the 3k model.
Thanks for any help.

 

I can't tell you what your power band is but I am going to wish you luck with the ACC converters. Everything I have read is that they are never accurate with their claimed stall and they don't hold up to much power. But, I do not have personal experience with them.

 

When you stay "stall" what do you mean? Hit the gas and it hits 4200 rpm right away? Or the proper definition of "stall" - power brake it (with the parking brake on) and it revs all the way to 4200 and holds there?

royalchoppers might be on the money with the "too much power" statement.

Depending on how much power your putting out, a converter might slip all the way to the red-line.

 

With your shift point being at 5500 it makes me wonder if your problem is in your valve body. I wouldn't think that your converter would dictate the shift point.

 

I want my shift point up there. The problem is the stall is to high. Is it possible that valve body is causing that also?

 

I think your problem with the higher than desired stall is because of the ACC converter. They are known for not having accurate stall compared to their claimed stall. Check out the Precision Industries website. They have some of the best converters and provide lots of information.

 

Hitting the throttle and the revs you reach is called "Flash Stall" and is what you launch at unless you are a power braker.

 

What I am refering to is holding the brake in 4 high, slowly step into it and at 4200 it finally locks up to the point that I cant hold it with the brakes anymore. Then it lantches.

 

I tried smashing the throttle off the line and it seemed to kick in at say time as holding the brake(4200).

 

That's the whole problem with convertors, same one in a different vehicle(or motor) will react differently. You can't just sell a "3500 stall" convertor, as every motor will make it react differently.

 

Before I ordered it I spoke to ACC tech and gave them all the ins and outs of my truck and engine. The guy i spoke to said this one should stall at 3000. He also said by braking and holding it at 1800 then smashing the gas I should get 3500.

 

Thanks Larry, that was the point I was trying to make

 

I know NOTHING about this crap, but from what I've seen my friends go thru with race cars I know they are the DEVIL!! LOL!! The MORE power(torque) you put thru them, the more they will stall. So your big 428 is able to push thru it more then a 360 can. It will "seem looser" with a big motor.

Gawd, I love my clutches!!

 

Maybe this will help. You can see the stll in action.
YouTube - 3000 rmp stall

 

Just an update. I put the factory covertor back in. I now know it is nothing to do with the new trans. One major observation, my shift point went from 5500 to 5000. That tells me that it was still slipping 500 rpm at 5000. Is this correct?