For a 400" engine? World Products Sportsman have been the budget choice for decades. Pocket port them as they will reward you for every penny spent on pocket porting. You will be hard to find a better iron head for the 400.


Ooops! Looks like Mr. Jackson beat me to that one.

 

This was my experience also. Even with BB heads....the guys wanting big $ good luck the 90s came and went.
I was lucky to get 100/pair for some decent 290s and square ports.....could not give away a perfect 396..threw it in a pkg deal with a virgin 400 which went cheap too. Who is building these anymore??(almost noone).

 

OK...some of the knowledgeable engine guys help me out, because I see a lot of posts like this, and a lot of answers, but I have some questions. For a compression ratio of 10:1, you're looking at a power band from 2,000 - 5,800 with an intake duration selected to attain that power band based on the displacement of the engine. Using the Wallace racing calculation tool, a 400 spinning at 5800 rpm requires a head that flows at 230 CFM (assuming an unrealistic volumetric efficiency of 100% for a street motor). For 90% (more realistic), the CFM requirement is 207.

Internet research (for whatever that's worth) indicates the stock 882 flows about 200 max, which isn't so far below the maximum required for the application, and the stock 041 flows up to 225 (couldn't find numbers for then 997). So why all of the advice to spend hundreds of dollars to purchase performance heads when the set of 041 heads will meet the calculated requirements? Some recommend using the 041, which seems like the logical choice to me also. Just trying to learn and wondering if I'm missing anything. Thanks.

MajD

 

Because there is not a head made by GM that is bigger than 165cc’s.....about 40cc’s too small for any kind of performance 400 build. You may get the CFM up there....but the port volume is too small.....and you are trying to suck air into the cylinder, bigger engine needs more volume.
Regardless of what the calculator says.....230 cfm will not get even a 350 into the 400 horsepower range.....and it is not all about peak flow numbers either, it is about low lift numbers starting at .200. GM heads have horrible low lift numbers.....and low lift numbers are important to get the air starting to move as the valve starts to open....
I was impressed at my L-79 after I did the heads on it.....but there were over 40 hours in those heads.....whoever has it now and takes it apart will ****.....but if I had to do it over again I would bolt a pair of Dart 180’s or the new Trick Flow 175’s on it.....
Even with all of the work done to my heads at that time.....it would have made more power with an out of the box Dart head.
I have Dart 200’s on my 406.....IMHO, there is not a better head you can bolt on a 406 for the money.....
To get an 041 head anywhere near what a Dart does would cost over $2000....and good luck finding a guy these days to port one properly....almost nobody hand ports anymore and there are no programs that I am aware of for GM heads....throw them away.

Jebby

 

Thank goodness you were up early jebby, and your brain working to capacity.
This is kind.of like people covering the end of a hose with thier thumb and the water sprays further so they think they have more pressure. All this stuff works together but they aren't the same.

 

Another issue with some budget heads is: small, valve spring pockets.
New heads come with a maximum cam lift suggestion due to the diameter of the spring and diameter of the spring pocket.
Can the pocket be enlarged? Yes. Is it costly? Yes. Will you be able to run a bigger cam? Yes. Is it worth the cost of machining the pockets larger? Seldom.

 

Jebby,

Thanks for the information. I know it's about more than peak flow numbers, but I was not aware that the GM heads flowed so poorly at low lift.

MajD

 

Jebby,

What is your experience / assessment of Vortec heads (062 casting) on a mild 400 build...say something under the 5500 RPM range. Thanks.

MajD

 

I have only built two engines using Vortec heads. They were both 355's.....and were twins......CPI injected Vortec setups with headers in mid 90's pickups. Comp X4270HR roller cams with 1.6 rockers. 10 to 1 compression. Absolute beast torque right off idle.....would rev to 5500 easily......and that is how you can expect a 400 to run with these heads but add even more torque and lower max RPM. Engines like that are fun for a car but get boring quick because you think it should rev higher. The Vortec intake port is still too small to feed an engine that large upstairs......174cc's I believe...they came only on trucks and for good reason......
A good 400 build needs a 200 head or better. I like midrange power so I went with the 200 although some will argue that a 215 would be more suited. I can tell you that my 406 on 275 Nitto's is as much as you need on the street. It presses the limits limits of the stock Muncie and suspension......I do have a host of upgrades in the rear of my car, but without slicks it is a wash in 1st and 2nd gear......I bought some slicks but have yet to try them, I am hoping for high 11's......
The point is that to make real power......you need a real head and anything else you put on it will be disappointing. The difference is pretty big.

Jebby

 

Chevy did after all put 325 cc ports on hi performance 396's.

 

My 882 heads:

 

Heck I can do better than that. Here's mine!

 

Bet that made some noise!

 

I've got a line on some iron eagle platinum 215's...
I'll need to change out the valvesprings, as they are set up for solid roller. I plan to go XR276HR, 10.1:1 compression (give or take)
2500 stall on the TH350
given the retro-roller lifters, any issues going with roller TIP roockers, as opposed to full rollers? I'd like to sue the stock valve covers.

 

roller TIP are a relative waste of resources ... Most of the friction is in the fulcrum & Not at tip ... want evidential proof? Simply look how GM engineered virtually all those newer LS & LT motors ... they have a nice roller fulcrum but a flat slider tip.

Roller TIPs have a relatively hi-friction ball-pivot fulcrum just like OE C3 rockers. There are some very good true roller rockers out there ... pretty sure you can buy genuine USA-made in Florida by Scorpion for about $200.
an example
If valve cover clearance is an issue, perhaps double-up on gaskets

 

The roller rocker has very little to do with friction reduction. An oily stock rocker is VERY SLIPPERY at the fulcrum pivot. No real friction there. The roller tip helps reduce side load on the valve guides theoretically. Stock GM conventional rockers are also not anywhere close to the 1.5 rocker arm ratio (actually around ~ 1.37) so there is some loss of lift there.

The main reason to use roller rockers is conventional rocker arm pivot ***** are not able to handle loads over 350 LBS of valve spring pressure over the nose of the cam. Roller cams require high spring pressure to prevent launching the HEAVY roller lifters at high engine speed. The conventional rocker arm pivot ball will not handle the load of a roller cam spring. Conventional rocker ***** will burn at the pivot and/or punch out at the bottom when loaded above that 350# pressure limit.