Hello eveyone,
I am in the planning stages of my next project and, I would really like to hear your advice or comments. I am planning to build a 406 for my '72 Vette. I would like to build something with about 9.5-to-10.0 to1 compression, Edelbrock performer RPM intake, headers,etc. The car is automatic and I will probably run something around a 3.55 to 3.73 rearend, with about 2000 to 2200 stall. This car is a weekend crusier. Probably won't see much if any track time. I would like to use a hydraulic flat tappet cam. Does anyone have any suggestions as to which cam would be good in the engine? Any personal experiences with this engine?
I know my specs are kinda vague but, as I said, I am just planning right now. Any advice would be greatly appreciated.

Thanks,

Mike

 

You're lucky. It's a 72, so you don't have to observe strict smog laws. That frees you up on cam choices a little.

Since you want a streetable 400 with good torque, but not so much emphasis on ragged idling drag race cams, I would go with a cam that will make good power to around 5600 rpm. A cam like that would have amazing torque down low and in the midrange. And by not revving much beyond 5600 rpm on a regular basis, you will not need to spend the massive extra bucks on forged crank and rods. In fact, a hypereutectic piston would be a good choice.
(But DO spend the extra money on having those rods shot peened and polished, and use ARP connectors everywhere).

The lobe separation angle should be wide so that there isn't much overlap between intake and exhaust lobes. What this will do is dramatically smooth out your idle. So I'll give you some general guidelines:

1. If you want a buttery smooth idle and perfect street manners, look for a LSA of 112 to 114 degrees. You'll also get the best vacuum too.
This cam will give you a lower peak power, but will broaden out your torque curve. Off-idle response will be excellent and extremely powerful.

2. If you want a slight lope in your idle, You can try about a 110 degree LSA. This will also give you a little more torque peak, and still acceptable idle quality.

3. If you like a pronounced lope, and a peakier midrange instead of so much bottom end emphasis, you could go to a 108 LSA. Anything under that will start to get somewhat ragged for traffic light to traffic light travel. And hard to drive slow.

I would suggest an Iskendarian 230/230 (@ 0.05") hydraulic flat tappet with a 108 degree LSA if you like #3. The Isky cams have VERY strong midrange torque, with a very attractive lope in the idle. I'd shift this at 5600 to 5700 rpm, but you can occaisionally probably pop up into the 6000 rpm range. (Just don't make a habit of that if you choose to save thousands on cast, instead of forged parts).
The symmetrical grind Isky demands a good exhaust system. Make sure you have good full-length headers and a good true dual exhaust system, preferrably with some kind of crossover.

If you want to run your stock exhaust, or stock manifolds, (which I don't recommend), then by all means, get a dual pattern grind. Something like a Comp, Edelbrock, etc. Also try to use a dual pattern grind if the heads don't flow that well, such as stockers. (For you, the Edelbrock heads would permit you to use single pattern if you combined it with a great exhaust system).

I think Edelbrock's cams run well, and are dyno matched to the heads and intake combo that you want to run. But they are a bit mild. Which is okay for you.

I'd stick with around a 230/230 @ 0.05 with narrow LSA's or a 232/242 @ 0.05 with wider LSA's. And stick with stock lift ratios on the rocker arms if you don't want the extra wear on the springs. That's a decent street combo.


[Modified by MoMo, 4:41 PM 10/5/2002]