I have a set of Motown 220 heads. Does anyone know anything about these heads? Will they make good power for a well built 406? I'm looking for approx. 550 to 575 HP...  

World uses these heads on a 600 horsepower 427 small block. So, spin your engine several hundred rpm more and use a slightly larger solid roller cam and it's probably possible.  

Thanks GibTG... I have a 400 SBC .30 over; with SRP flat top pistons. Scat 5.7 rods, Scat forged crank, Comp Cams XR292R solid roller cam, cam specs are as @ .50 .254 I .260 E, .582 I .588 E, Comp Cams belt drive, Super Victor intake, Hedman Elite 1 3/4 headers, MSD ignition, Have not decided on a carb yet. Any ideas? Engine is in a 71 Chevy Pro Street truck by the way. Thanks....  

I think that combo should be on the borderline of your 550 horsepower goal. Maybe could try some 1.65:1 rockers on the intakes to help get you there if the valvetrain can handle it...

I would probably recommend a 780 or 800 Mighty Demon.  

850 mighty demon with annular boosters  

Nice...

That's a good point.  

Annular boosters are suppose to give better throttle response right?  

My valve train should handle 1.65 rockers. The heads are set up for a .700 lift solid roller. Why just on the intake side though? Not sure if it makes a differance but I have 2.08 intake valves. Thanks for all the replies.  

that carb with annular boosters will give your truck better throttle response as well as increased crusin drivability,as the boosters are more efficient at lower rpms than a standard dogleg booster.also,u want to accelerate the intake valve as fast as possible,thats why Gib mentioned the 1.65 rocker,as the cam you have is a mild roller that is not really aggressive compared to other roller cams.but on the plus side,if u increase the rocker ratio on that cam,you will have .624 lift after u factor in the lash.good luck with it  

The bottom line is that the annular boosters do a better job of breaking up the fuel at low speeds. This is an attempt to regain the fuel distribution and quality that is reduced when switching from a two plane manifold to a single plane manifold and from a "solid" manifold to a "air gap" manifold - both of which can induce puddling and poor atomization if not addressed. Annular boosters can make HUGE improvements in low-end power for engines that focus on top-end.

The rate at which the exhaust valve opens is not nearly as critical as the intake valve. The intake valve must be opened a sufficient amount for the engine's demands, and if it isn't huge drops in volumetric efficiency and power will result...

Think about the three most significant aspects of an engine's induction: the vacuum the exhaust system creates in the cylinder, at and around the piston's maximum speed, and the air's inertia while entering the cylinder. Two of these three events occur relatively early on in the induction cycle so you can understand that if you can have the valve opened as far as possible during these events you can reap large benefits in terms of being able to induce air and fuel.

So, in many cases I favor "split-ratio" rocker sets as the added lift is so much more vital to the intake side. Added ratio on the exhaust can help gain a few horsepower in some cases and will usually help on the extreme high-end, usually helping most out of the engine's tuned range.  

well said......  

Ok thanks. It makes alot of sense. I realize that my cam is a little mild compared to an all out racing cam as far as rollers go. but this is what Comp Cams tech line recommended. Would I be better off going with a differant cam? I already have my 1.5 roller rockers. And the cost would be about the same. I really want to stay streetable and be respectable at the track on weekends. It may be a stretch but I would like to see mid to low 7's in the 1/8.  

you have to remember that comp cams designed these cams with street use in mind,and from what ive seen personally,they work very well and are very reliable,if everything in the valvetrain is spot on.i would personally use a 1.6 rocker on the intake with your combo,to accelerate the intake opening.you are on the right track,good luck with it  

Thanks BigCam. My buddy has a set of 1.6 rockers he will let me try. Once i get everything together and running i will compare them both and see what happens. Again, thanks for the info...  

your welcome......