[bober]

Are 670 400 heads a good choice for a 400 build for HP or should I look for something different ? Thanks

[Navy Horn 16]

I'd start here:

http://butlerperformance.com/c-12347...der-heads.html

[61-63]

Good head with large valves and screw in studs from the factory. For a street engine that will run on pump gas you will need dished pistons to be 10:1 or lower cr. With aftermarket aluminum heads you can have the large valves, screw in studs, and run
higher compression with flat top pistons and run pump gas, but they are more money. Either head can be ported to really flow well. If you have plenty of money and the number 670 cast onto the center bosses isn't important I would say get aluminum.
To save a little money and/or if the 670 being on the head IS important I would say use the 670s.

[gtofreek]

They are good heads. There are some dished pistons from Icon that have a 14 cc dish for a 400. One 413 I did with 670's, came in at 10.1:1 compression, and made 479 HP, with an iron q-jet intake, and points ignition, on 91 pump gas. Made over 500 HP with a single plane intake, and over 500 ft. lbs. They are capable of making good power. I would say they are the best flowing, by far, iron D-port head there is.

[GRX]

They are good heads, but a set of 6X can serve just as well in my opinion. One thing most always over looked when using 670s is the cylinder notch needs to be at a different location than later engines because of their unique chamber.

[chiphead]

They're one of the better high compression big valve heads. I run them, and have for many years. Good stock port flow, later valve angle, typically come in at 76-79 CCs stock chamber.

The problem is by the time you rebuild and port a set for high HP use, you've spent more money than if you'd bought a set of 72CC aluminum heads. It's just not worth it, even if you get them free.

Spend the $2400 and get a set of aluminum heads. I wish I had.

[92GTA]

I'm running a set of totally stock (except for hardened seats, Ferrea valves, & Comp springs) 670 heads. I have a -23cc dished ROSS pistons from Butler, I'm at about 10:1.

I'm putting out ~450hp/550tq at the motor according to dyno sheets. Also have a ported Torker II and a 750 Holley 4150. Cam is in my sig. Engine is a 461.

I'm going to e-heads from SD perf in the future with a new cam so I can put down some real power.

[steve25]

Well if your going to push the compression ratio of your building a bit, there closed chamber is less likely to make for ping and knock conditions, there just a little more on the dirty side emissions wise in comparison to the 68 and up open chamber heads.

Flow wise they are basically as good in terms of high lift flow ( .550" ) as any other high comp D port heads from 68 on up, in fact they flow a good bit more Intake air in the lower lift range of .200"to .300" then any other D port iron head!

Just the right valve job and a 4 minute long Intake valve bowl clean up can take them from a stock 205 to 208 cfm up to 230 cfm .

A lot of people shunne them due to the large Exh air injection boss on the roof as part of the valve guide, but it does not really effect the stock Exh flow and that's why the factory put it there!