Ok, I am thinking of this combo for my new 406:
Factory 400 block .030
Scat 4340 3.75 crank
Scat 4340 I beam 6in. rods w/7/16 cap
SRP -16 dish forged pistons
Brodix Race Rite 200 Heads w/67cc chambers
Comp Pro Magnum rockers
Victor jr. manifold
Holley 750 mech/dbl pump
Hooker 1 3/4 super comps
I would like you guy's to help me pick a cam. I was thinking of a solid flat tappet maybe a comp 306s or maybe a lunati 401A5? I am open for suggestions. Or do you think a hyd. roller would be better?

Your compression ratio is only 10.0:1 with those pistons, way too low for the Comp 306s.

With your compression ratio about the biggest cam I would recommend is 280* advertised, 230* duration @ .050, 108* LSA.

With that cam in a 406 you will be shifting around 6000 RPM so a hydraulic roller cam would be ideal. And as long as you are shifting at lower RPMs you might as well use the Performer RPM Air gap (dual plane).

Eric do you think I could get away with boosting the compression up to 11:1 without having any detonation problems?

On 93 octane sorry.

I suggest if you prefer a certain brand to call them and have a professional set you up with what they feel is the best cam for your application. Or call Comp Cams they work with Brodix on matching up heads and cams. The thing is you need to be very specific with your info you supply to the guy about what you have and what you want. Things such as how much time it spends on the street. Are you concerned with low rpm tq ? What rpm range are you wanting to try and shift at. A hyd Roller would give you the better of both worlds figuring about a 6000 shift point with those heads and 400ci.

Steve

It will see more time on the street, but I am looking for mid 11 sec. et in the quarter. Manual trans.

Definitely go roller if you can take the hit $ wise. you will be able to get more out of it with the roller grinds tq and hp should both go up with the proper grind. I always like having a custom ground cam for my particular application because even though a lot of small block builds are close in most cases the cars are not and what the driver does with them isn't always the same. This is why you see a whole lot of guys who buy crate engines first change is jerking the cam out for a swap. (Another reason I do not care for crate engines) There are just to many variables that can play into it unless you just have a really common strait forward setup which we all know almost no one has the exact same car setup and the same expectations from idle characteristics and so on. I'm not saying a off the shelf grind isn't out there that will make you grin, heck there are thousands out there but I like mine to be as precise as humanly possible for me. :D

Steve

Thanks Steve and Eric, I have been trying to figure out this build for a while, looks like I will be looking into a roller cam. bite the bullet dollar wise lol.

JCDubs, I am in the middle of a 406 build myself. I am using 5.7 I beams and -12 dished pistons. The cam I picked is the comp 280. I picked this cam because I am running AFR 195's and according to Lingenfelter...the 280 is the perfect choice for all around performance for my set-up. I agree with Eric on the 306 being too much cam. I would call Comp and speak to the tech-line folks too. We have some awesome engine builders here @ TC, but I like to hear what the manufacturer suggests too ;) Good luck with your build up!!
Dano:beers:

I have flat tops and 72 cc heart shaped combustion chambers running 10.6:1 with Victor Jr. heads and RPM Air Gap and I am making 524 hp with grind number XR276HR which is two lines below a grind that is similar to the one run in the Z/28. (spec number wise). Because of the larger displacement of the 406 (compared to the 302) it doesn't act any where near as radically, having a noticeable cam, but relatively smooth idle. I was looking for a broad torque curve and a 6200 RPM shift point in a HEAVY car.

Your needs may vary. I would suggest investing in a Desktop Dyno program, and if your serious about performance a desktop drag strip simulator as well. CompCams sells one that just happens to have their complete cam catalogue (for an additional nominal fee), that allows you to plug your motor design into their car simulator. I highly recommend it for the entertainment value alone (or am I just strange because I would rather build virtual engines and race them than kill space invaders).


Larger Dave

An extra half point of compression would help a lot. I am a bit more anal than many on matching compression and camshaft but IMO you are leaving big power on the table if you do not.

With your mid-11 goal I would look at 10.5-10.75:1 compression and for a cam something real close to the XR288HR. That cam is 288/294* advertised, 236/242* @ .050, .520/.540" lift, 110* LSA. The Vic Jr or the RPM Air Gap would work well with this combo (I like the Vic Jr personally).

To get your compression ratio to 10.5:1 I would look into a -12cc dish piston. Use a zero decked block and a .035" thick head gasket. The other option would be to have your heads cut down from 67cc to 63cc (should be about a .024" cut).

PS. If you get a Comp hydrauliuc roller special order it with the two piece core and have them put it on a small base circle while they are at it.

Ditto 280/230 cam!!

I have a 292/230 in my about 9.5 to 1 406 that I pulled to make room for my 496 and it was soggy down low!!

pdq67

I'm running the CompCam280H/230 cam but in a flat tappet hydraulic. I don't think you'll get much better times with a roller of the same size (maybe .2 or .3 better????).
I'm getting ready to go big.... just don't know what yet.

I know we aren't talking about them here, but please consider a decent solid lifter cam!

And save some money.

Somebody please run a CC 282S through D2k or EA using his combination..

pdq67

An excellent cam for that setup is a 288/296 Ultradyne HR8.
A Hyd Roller it has 234/242 @ .050. Lift is .530/.530 on a 108 sep.

Shift anywhere from 5400-6000 Rpm your choice.

You might consider a single pattern version depending on your heads too. Should make for more mid range torque.

BTW, Lunati and Bullet can make the cam for you.

Ditto 280/230 cam!!

I have a 292/230 in my about 9.5 to 1 406 that I pulled to make room for my 496 and it was soggy down low!!

pdq67

How`s that 496 running ? Any track times with it yet?

jc, we have almost identical short blocks. I run the same pistons but use Eagle for the crank and rods. I use AFRs but I beleive the race rites outflow them...anyway, I absolutely love my XR294. I have run a best of 11.26 with it but have yet to run with my new 8" converter in the quarter. I am expecting/hoping for 11.0x.

If you are just looking for mid 11's then you could go smaller on the cam (XR282 or 288) and could certainly do it with a flat tappet cam if the budget is tight.

I had run an 11.74 with the mild Performer RPM hydraulic flat tappet so I would think a low 240's solid would get you in the mid 11's.

Thanks alot guy's, Can't say that enough. I will keep you guy's posted.