Well, the 406 has been apart for a long while now, things have gotten better so it's gone back to the machine shop. Right now it's getting cleaned and the block is getting decked. Something that I should have done before but didn't. Compression should be about 10.2:1. If anyone is familiar with this build up it's a mild 406, stock crank and rods, good rod bolts, hyper pisonts. 288XR roller cam, 220cc protopline heads. 2800 9.5 ACT stall, 3.23 gear. Car ran 7.8's in the 1/8 with so suspension work and on pep boy 255/50/16 tires. The car always smoked, always. burned a lot of oil. took it apart, found out i had put the second ring upside down, in all the cylinders. Now that I am putting the engine back together I have found the MORE syndrome kicking in. I am getting the 294xtreme roller cam, which is a step up from the 288. I had the heads flowed, and I don't have the numbers yet, but mike at the machine shop said they flowed 290+ at .750 lift. the problem that I am having is this, do i put the engine back together the way it was, 288XR roller and RPM air gap intake, or put the 294XR roller in it with a single plane. according to desktop dyno, with as accurate info as I can put in it, with the 294XR cam and single plane intake would make almost 600hp. Now I'l all for running stock parts as hard as you can, but if I start making this much power, the mains are starting to worry me, as is the stock harmonic balancer. the car ran great before, and was as streetable as my stock 89 305 TBI. I don't want to get into a situation where the car is no longer fun to drive, or I start blowing stock parts up. I thought about putting it back together the way it was, and then changing the intake and cam later on. Any ideas? I was going to order parts tonight, but decided to wait till I talk to a few people. Thanks.

I'd save some money and get a set of 2352 or better forged pistons If I were you because I've seen 2many 400's windowed when the hyper piston came apart. The long stoke short rod makes the piston rock more than any other sbc high rpms with that rocking and a hard brittle piston can equal a disaster.

Also a set of 3.73's would help considerably.


L2352 are a little lighter but can be used without balancing the dampner as long as the rubber ring is in good shape will work fine .



PS if you decide to sell the 288 cam PM me a price I have a 350 I'm building.

I pretty much agree. There is no way i would run stock rods and crank at the rpm levels that motor will spin to. Its not gonna be pretty the first time you really get on it.

I agree as far as pistons/rods go.You need to have a good set of forged slugs,as well as a quality I beam connecting rod.

While it would be best to go with a forged steel crank,I am still running a cast unit,although I won't say I should be.But I really think that it being a hydraulic roller as opposed to solid will help keep the revs down just a touch,so you PROBABLEY can survive a while with the stocker.The key,I have found,is to keep reciprocating mass as low as possible,and use your head.When your already pushing parts beyond their limit,one wrong move will ruin your whole day!

I think the rods would be Ok to about 6500 max most 400's don't
like to rev and the hydraulic roller as mentioned previously don't like real high rpms either valve float usually occurs before 6500 rpm. Match your cam to your max rpm you will be fine. Just remember to get you some forged pistons if you make no other investment in this motor keep your block around for a few more builds.

Lf you were to take a hammer and hit a hyper piston it would break into many pieces (kinda like the biggest piece of a piston I found in one that shattered was about the size of gravel)

If you take a hammer and hit a forged piston it will bend and fold it won't come apart easily. (its insurance in its purest form.)

I thought the XR was a solid roller cam?

That's great that your heads flow so much at .750 lift but what good will that do you on a street motor. Before you pick out another cam, look at the flow numbers and base the cam on intake to exhaust ratio. My heads have a very high intake to exhaust ratio so consequently I'm running a single pattern solid roller. I would not hesitate going with a single plane intake for your application. You will lose a little bit of torque down low. The trade off will be worth it in the mid and upper rpm.

However, the combination of single plane coupled with the XR 294 will drive the peak HP well above 6000 rpm.


www.geocities.com/dzperf

Aren't hyper pistons be OK unless he detonates it. For a street car I would think the hypers should be adequate.

The rods are 5.7 reconditioned rods w/ ARP bolts. The pistons are KB 147's.

The cam is a 288XR hydraulic roller.

I talked to mike at the machine shop today and he said that 600hp is starting to push it on stock parts and he said 400 blocks aren't known for being really strong.

The smart thing for me to do is put it back together the way it was and run it.

I normally spun the motor to 6000-6300 with the 288XR cam. I don't know how much the second ring being upside down effected it. Mike seems to think that it's going to make a big difference.

The car never hooked, it would spin the tires at a 40 mph kickdown. I figure thats why the rearend survived.

Mike talked about putting main studs on it, then it would have to be lined honed. I put new GM main bolts in it when I built it last time. I don't know how strong those are. I noticed that ARP sells different main stud kits for 400's, I know the main bearings are bigger, which makes me wonder is the bolts the same? There wasn't a seperate part number for it.

Thanks for the advice guys.

what are the specs on these cams? It doesn't matter what the heads flow at .750" if the cams max out at .500 or so.

FOrged or Hyper, it all depends on the application. And how they break makes no difference, a melted forged slug or a shattered hyper. Both can destroy an entire motor. I thnk the hypers will be fine for you.

As for the intake I wouldn't be going with any single plane unless your heads flow super well and you don't mind giving up a buch of low end grunt. Seen 625+ on a 432ci. and dual plane.

Just because you put main studs in the block doesn't mean it'll need to be line honed, but it should be checked nonetheless. Most of the time if the line bore is good with bolts, the studs wont change it enough.

Your HP level will be fine for a stock crank, but a set of at least Eagle rods would be a little insurance.

Don't put gears in the car until you figure out where the power peaks at. Also take into account the tire height and ratio in the trans.

As for the desktop dyno, throw that POS away. It's all theoretical. Let your engine builder put together a combination that works together. If this Mike guy is all you make him out to be, then he should be able to put together a strong motor. I'm sure he's built a 406 or two.

The cam specs, for the cam I have now is

288/294 adv., 236/242 @.050 .520/.540 110 LSA

the specs on the cam I might get is

294/300 adv. 242/248 @ .050 .540/.562 110 LSA

obviously I am not running .750 lift, it's going to be less than that. I haven't gotten the flow sheet yet so I don't know what they flow at .600, which is more what I am concerned about.

I don't think that 242/248 is that big for a 400.

The first one you listed is an excellent cam. I've used it in a couple of my 383 buildups for customers. It's in our dyno mule that made around 470 fwhp on a 383. Made 510 with it with AFR heads for a customers Nova. I wouldn't go bigger than that, especially for a street motor. To get the potential out of it you'll have to run an intake setup that will sacrifice too much torque and you'll need too much converter and gear to keep it streetable. Wont be as much fun to drive/cruise.

Give me a melted forged slug over a broken hyper anyday. I've seen to many windowed blocks to EVER use hyper pistons in a 400.
When the rod and pin is done sliding up and down the side of
the bore it aint pretty. The only reason to build using hyper
pistons is if rules forbid forged. Just ask anyone who races with
motors making the kind of hp your talking. As posted earlier
detonation can happen with the quality of gas today thats
all it'd take. On a 11 to flat top 400 its 10 times more likely.

BTW I seriously doubt your hitting 480hp much less 600 not flaming just being honest.

Hey LilJayV10, what's up?

I thought you gave up on the car and were looking into other things? Anyways, glad to see you're sticking with it!

My honest opinion? Put the rings in the right way this time and see how it runs.

I can tell you from my experience, mine ran much better after I had my block honed and installed TSS gapless rings. No oil burning, no dealing with oil fouled plugs misfiring all the time. Amazing how firing on all 8 improves performance! lol

600 HP at 6500 RPM's? I think you're at a crossroads so to speak. Strip car or street car?