BBC-Aluminum heads?

[Bandit]

Hey all,

I am trying to justify the 2 grand + it would cost me to have a set of new aluminum Edelbrock or equivalent heads on my 402 Chevy Big Block. I am trying to guesstimate what kind of power and torque increases I would gain.

Sorry I don't have all the specs with me right now, but I'm currently running the following:

Block bored .010 over for 408 ci
Domed Wiseco 9:6:1 pistons
Stock oval port heads 2.19" Int 2.25" exh
stock stamped rockers
Comp hydraulic roller cam <.600 int/exh
Crane hyd. roller lifters
Edelbrock Performer intake
Holley 750 vaccuum secondaries
Hooker 1 5/8" primaries...2 1/2" dual exh w/H-pipe

Etc...basically your typical mild street build with the huffing advantage of the roller cam.
Never been on a dyno, but we estimate 400-430 flywheel hp/450 lb. torque.
I would like to squeeze out closer to 500 hp from her, how close can I get with just the heads?
Also, I want to keep the stock exhaust port locations for ease of header fitment. So no radical Brodix monsters for me.
I will likely combine the heads with an Edelbrock Performer RPM intake.

So:
1. How much power/torque can I expect to gain?
2. How much weight will I drop off the nose of the car?
3. Can I drop compression ratio a point or 2 (to support future procharger install) and still see a decent gain?
4. If you have any suggestions for runner size/chamber or head shape, I'm all ears!
5. This is a "tall-deck" block from a truck originally, will this mess me up?

Of course I know any estimates will be ballpark, there are like 30 different heads from Edelbrock alone that will fit my engine.

Sorry for the long post, but I value your inputs.

Paul

[EFI69Cam]

Hey all,

I am trying to justify the 2 grand + it would cost me to have a set of new aluminum Edelbrock or equivalent heads on my 402 Chevy Big Block. I am trying to guesstimate what kind of power and torque increases I would gain.

Sorry I don't have all the specs with me right now, but I'm currently running the following:

Block bored .010 over for 408 ci
Domed Wiseco 9:6:1 pistons
Stock oval port heads 2.19" Int 2.25" exh
stock stamped rockers
Comp hydraulic roller cam <.600 int/exh
Crane hyd. roller lifters
Edelbrock Performer intake
Holley 750 vaccuum secondaries
Hooker 1 5/8" primaries...2 1/2" dual exh w/H-pipe

Etc...basically your typical mild street build with the huffing advantage of the roller cam.
Never been on a dyno, but we estimate 400-430 flywheel hp/450 lb. torque.
I would like to squeeze out closer to 500 hp from her, how close can I get with just the heads?
Also, I want to keep the stock exhaust port locations for ease of header fitment. So no radical Brodix monsters for me.
I will likely combine the heads with an Edelbrock Performer RPM intake.

So:
1. How much power/torque can I expect to gain?
2. How much weight will I drop off the nose of the car?
3. Can I drop compression ratio a point or 2 (to support future procharger install) and still see a decent gain?
4. If you have any suggestions for runner size/chamber or head shape, I'm all ears!
5. This is a "tall-deck" block from a truck originally, will this mess me up?

Of course I know any estimates will be ballpark, there are like 30 different heads from Edelbrock alone that will fit my engine.

Sorry for the long post, but I value your inputs.

Paul

The tall deck is going to mess up your header location anyways.

For a 402 the ovals are hard to beat, but if you have have aluminum heads the edelbrock "Rovals" are one of the best flowing heads on the market short of AFRs and some of the huge runner heads like brodix.

Personally, I'd spend money getting a short deck block first, no sense carting all the weight and going through the bother of a tall deck block for only 402 cubes.

[Bandit]

For a 402 the ovals are hard to beat, but if you have have aluminum heads the edelbrock "Rovals" are one of the best flowing heads on the market short of AFRs and some of the huge runner heads like brodix.

What's a "Roval?" I have never heard this term before.

Guess I should have explained my situation better: I have been running this engine for about 3 years now. No problems, exhaust fits and the motor seems to work well with my suspension setup--but I could use a little more juice. Want to keep it streetable though and not ready to mess with nitrous yet.

I would prefer a new World or Shafiroff 540 , but it just ain't happening any time soon. Anyhow my 402 is going strong, would just like to upgrade a bit and shed some lbs. What problems would I have with aftermarket heads on a tall block--I thought they were the same dimensions, or if not, I could just use thicker gaskets?

Paul

[rocketman]

I you have headers now there's nothing change but the heads.

I don't the Edelbrocks heads,I would go with a AFR's,that small of a motor you don't want a crazy big head anyway.You might just port the heads you to,there good power alot cheaper than new heads.

If you are thinking a big cube motor like a 540,just go 632.

[EFI69Cam]

The edelbrock 454-O heads are the ones with the rectangular oval port. I would not put even the 305 CC AFRs on a 402. A 402 does not have the displacement to build any velocity through a port that size.
I have the GM version of the edelbrock ovals on my 540 and although I am considering AFRs, I will try my current heads first.

[rocketman]

if you could find some aluminun 396 hds those would be perfect for it

[442olds]

Good luck finding some factory aluminum 396 heads for less than $2000. For the money the eldelbrock/gm perf part head is the best there is and it uses the factory exhaust port location to boot. I have a set I'm working on putting in my vette now. I can't wait.

But what I really have to ask is, being a tall deck, how long are your conecting rods. if your still using stock length 6.135's, you must have one heavy piston to push around. And what's bore and stroke are you running.

[MarkM66]

On a small cubic inch bbc. I don't think cylinder heads would be worth the investment, as your stock oval ports can keep up pretty will with your cubic inch. I'd put your money in building a bigger engine.

[xx_ED_xx]

You can easily build a 540 out of that tall deck. If i understood you correctly that you are running a 402 tall deck now..

[neki67]

What's a "Roval?" I have never heard this term before.

Roval is in between Rectangular and Oval.

[rocketman]

Are using a tall block,sound like you have a ten over 396 block.

You could pick 50-75 horsepower and lose 100 pds.

[xx_ED_xx]

402 is a .030 over 396

[TD509EFI]

5. This is a "tall deck" block from a truck originally, will this mess me up?

I'm getting confused here... GM only made 366 or 427 tall deck engines, which one is this?

John

[xx_ED_xx]

What i was wondering as well...

[rocketman]

402 is a .030 over 396

I knew that.math was a little wrong

[rocketman]

5. This is a "tall deck" block from a truck originally, will this mess me up?

I'm getting confused here... GM only made 366 or 427 tall deck engines, which one is this?

John

Thats my question you can't get a 366 to 408 with a strokin it

[Bandit]

5. This is a "tall deck" block from a truck originally, will this mess me up?

I'm getting confused here... GM only made 366 or 427 tall deck engines, which one is this?

John

You are correct. Just seeing if you knew that... o not really, some yahoo told me awhile back that it was a tall deck, but I have since realized that it is NOT a "tall deck" motor. So that's what I get for listening to my punk friends.

So now that we got that out of the way, my original question remains: which heads? Again, they must be a stock-replacement bolt on, I do not have the ability to fabricate headers etc. in my current location (in Italy). I am mainly looking to pick up an honest 50hp, maybe lower my compression a point or 2 (the gas here sucks), and drop 100 lb. off the nose of the car.
I am thinking I will go with Edelbrock "rovals like some of you suggested, but they have may choices of runner sizes etc. That is where I would like advise on what to invest in. Also, can I lower the CR a bit and still see good power increase? I would like to end up with a 9.4-9.5 ratio if it will not cancel out my gains. Right now it's at least 9:6:1, maybe more since I have had the heads shaved once.

That is why I am consulting with all you engine gurus out there.
Thanks--

Paul

[malihoochie]

The Edelbrock heads have a "odd" chamber shape. Be aware of this, 'cuz many people find out too late. It is a cross between a closed & a open chamber. I'd go with a smaller set of Darts or Brodix heads with a conventional open chamber.

Hope that helps.

[kman67rsss]

I am running a 402 BBC .060 over with 11:1 cr and have AFR magnum 305 heads. rund good and has 385 HP at the rear wheels. thats close to 500 at the crank. so it can be done

[xx_ED_xx]

Hell i am confused? so bandit you have a 402? with what heads currently?