400 sbc build

[deano1977]

hey guys im new here im going to start my rebuild of my 400sbc. im looking for aluminum 64cc heads im going to reuse my internals but I have a comp cams cl 12 212 2 cam specs 280/280 480/480 110 degree lobe separation I just want a torque monster any advise would be great!

 

[rich weyand]

Comp Cams says 2000-6000 rpm for that cam. That's not a torque monster.

The 12-235-2 cam would give you an rpm range from 1000-5200, with 490 ftlb @2500 rpm in a 400 sbc with 9.5:1 compression. THAT is a torque monster.

Cams are cheap. Don't spend a lot of money and time building around the wrong cam.

 

[85c10owner]

In a 400 sbc that cam will make plenty of torque. That is a pretty common set up and would run good. Yeah there are better grinds available. Im not a big fan of comp cams but I know a few who have used the magnum line with great results.

This 406 build uses a similar spec`ed lunati cam and would be easy to copy.

http://www.superchevy.com/how-to/148-0306-chevrolet-406-big-block-torque/

 

[Green79Scottsdale]

Comp Cams says 2000-6000 rpm for that cam. That's not a torque monster.

The 12-235-2 cam would give you an rpm range from 1000-5200, with 490 ftlb @2500 rpm in a 400 sbc with 9.5:1 compression. THAT is a torque monster.

Cams are cheap. Don't spend a lot of money and time building around the wrong cam.

I am with Rich. You are probably giving up anywhere from 30-60 ft/lbs of torque by going with the cam you have. A different cam will give you a bigger monster torque motor.

Don't go too big on the runner size for the heads (180cc, maybe 190cc?), dual plane intake, 1 5/8" headers and dual exhaust with H-pipe as close to the collectors as possible, and a carb matched to the whole combo, and you will be a happy man!

 

[85c10owner]

The 400 sbc can take more camshaft than your regular 350 engine. The 280 magnum in a 400 will make more torque than his tires can handle. And there is no way to say how much power would be lost or gained without using a dyno. I know of a 402 bbc which has a very similar bore and stroke to the 400 sbc and that engine is a hand full. There are mu h better camshafts available but the 280 will not be a turd in a 400 sbc.

 

[firebane]

What Rich is getting at is that you have a cam that starts to make torque around the 2000rpm mark. With our trucks being so heavy you want all the torque you can put to the wheels right from the get go.

If your looking for a torque monster you'll never be spinning the truck to 6,000rpm but perhaps maybe 4-4500 rpm instead.

Most people aren't pushing 6,000 rpm unless its a well built engine for horsepower instead and if you want to spin 6,000rpm perhaps its time to look into a LS

 

[85c10owner]

What Rich is getting at is that you have a cam that starts to make torque around the 2000rpm mark. With our trucks being so heavy you want all the torque you can put to the wheels right from the get go.

If your looking for a torque monster you'll never be spinning the truck to 6,000rpm but perhaps maybe 4-4500 rpm instead.

Most people aren't pushing 6,000 rpm unless its a well built engine for horsepower instead and if you want to spin 6,000rpm perhaps its time to look into a LS

Just because the book says 2000-6000 doesn't mean that's the only operating range. That cam in a larger engine like the 400 sbc will start making power sooner than 2000 rpms. Think about it, it's basically a bbc engine in a small package. Only difference to the 402 bbc is the heads. The 280 magnum in a 400 sbc will make more torque off the line than any street tire can handle. It's up the the OP but since he hasent come back I don't think he even sees these replys.

 

[bucket]

Just because the book says 2000-6000 doesn't mean that's the only operating range. That cam in a larger engine like the 400 sbc will start making power sooner than 2000 rpms. Think about it, it's basically a bbc engine in a small package. Only difference to the 402 bbc is the heads. The 280 magnum in a 400 sbc will make more torque off the line than any street tire can handle. It's up the the OP but since he hasent come back I don't think he even sees these replys.

I tend to agree with this. The 2K low range was given to the entire SBC family as a blanket statement. The average 400 with that cam would likely start making power below that 2K estimate, which should be a good match especially if the converter is a little on the loose side of things and the rear gear ratio isn't of the highway type. Even from a dead stop, 1700-1800 rpm would happen real quick.

 

[Green79Scottsdale]

 

[Don5]

I think this topic has been discussed and argued, before. Just saying. I am going to sit back since I commented on the last thread that had this similar question in it. I am also pretty sure the same guys weighed in on it as well.

BTW- Rich do you have a computer program that can run the numbers if you punch in cam stats, piston size, compression etc to arrive at torque and HP numbers?

 

[bucket]

To be honest, we could all discuss it till the cows come home and it doesn't really matter too much. We don't know enough of the other important details.

But what we do know is this:

Everyone has different driving styles and "wants" in an engine build.
That specific cam might not be the best choice.
That cam is by no means the worst choice either.

 

[rich weyand]

BTW- Rich do you have a computer program that can run the numbers if you punch in cam stats, piston size, compression etc to arrive at torque and HP numbers?

I use the Comp Cams Camquest software to compare the Comp Cams products. I don't usually offer much of an opinion of other company's cams. I figure the Comp software ought to do pretty well for their products, at least in comparing one cam to another. The software requires the entry of LOTS of engine parameters, but I have several standard setups now so that one is usually pretty close to what somebody is asking about.

 

[rich weyand]

To be honest, we could all discuss it till the cows come home and it doesn't really matter too much. We don't know enough of the other important details.

But what we do know is this:

Everyone has different driving styles and "wants" in an engine build.
That specific cam might not be the best choice.
That cam is by no means the worst choice either.

Of course. But he said he wanted a "torque monster", and with that cam he's 50, 60 ftlbs below where he could be. That's all I said.

As far as hooking up a lot of torque, the 1970 Buick GSX Stage 1 455 had 510 ftlbs of torque, and was a lot lighter than our trucks. It only had 370 hp, but it would smoke 425 hp Hemi Cudas and 525 hp Chevelle LS-6s in the eighth mile. Not in the quarter -- they caught up when they could get winding. But stoplight to stoplight, that thing was unbeatable.

 

[bucket]

Of course. But he said he wanted a "torque monster", and with that cam he's 50, 60 ftlbs below where he could be. That's all I said.

I understand, but is that comparing peak torque? You might have to sacrifice a whole tot of usable torque to gain that extra torque right off idle. Excellent off-idle power doesn't mean much when you are wanting to pull a trailer up an interstate incline at say, 2800-3000 rpm.

Again, we just don't know nearly enough information to give excellent advice. Hopefully the OP will chime in with some info and intended usage.

 

[85c10owner]

You have to remember that the 280 Magnum which is [email protected] will act much different in a 400 than it would in a 350. The 400 is bbc bore and stroke pretty much. It can take more camshaft and not loose torque like the shorter stroke engines will. It will depend on the heads but if you put a camshaft that is around [email protected] in there it will make a lot of torque but it will be done really fast. It wont make it to 5200 rpms. It might go there but the power band will long have dropped off. Read the "impersonator" engine build I posted. It`s a very similar engine and makes a lot of low end.

Another thing to keep in mind is gearing and tire size. That is going to determine a lot and if this is a auto is it a stock stall? Is there a mild stall? Some converters will have better torque multiplication than others depending on what they were designed for.

Again, the OP hasent been back to comment on this so why bother going round and round about it? Until he comes back to give some more input it eally doesnt matter what cams we suggest.