A12 heads 906.

[Cranky]

Iirc red (HP) vs blue(LP) painted valve springs would be the only difference between 906 heads with the stronger red springs coming on 335HP 383s & 375/390HP 440s.

Had a 70 383 330 horse Challenger (non RT), it had the blue engine but heads had the magnum (looked red) springs on it. 4 barrel with the 'big' manifolds and dual exhaust (with turn downs) and disc brakes. AC, PB, PS standard gauges. Bought it from the original owner who said the only things he did to the car was installed an Accel dual point, chrome valve covers and slotted mags which were still on the car when I bought it. 70 model cars were treated to the factory upgrade??

 

[Big D A12]

Just saw this thread and I am a little late to the dance. I know the engine for the original poster's car is already installed. I do want to provide the data that is out there on the A12 heads. Several references have been made in replies to this thread.

The 906 head castings are the same for the 440 and 383 cars for many model years. The differences applied to the valves and springs for the A12 are detailed in PIB #13. Hope this adds to the discussion.

D

 

[six-pack-mopar]

I have a pair of Mopar performance heads 3614476 that are similar to 906 heads but I believe they take an offset rocker assembly. From what I’ve been able to learn is they have the same combustion chamber as the 906 heads but they have more material that would allow you to do more porting. Is this something to put on an A12 car that already is missing the original motor? Thoughts? Thanks much for your input.

 

[33 IMP]

If it's not the original motor, I don't think it will matter what casting number the heads have. As long as they are iron, and look like 906s from the outside, with the valve covers on.
Quality offset rockers are expensive.

 

[Curiousyellow71]

I have a pair of Mopar performance heads 3614476 that are similar to 906 heads but I believe they take an offset rocker assembly. From what I’ve been able to learn is they have the same combustion chamber as the 906 heads but they have more material that would allow you to do more porting. Is this something to put on an A12 car that already is missing the original motor? Thoughts? Thanks much for your input.

You can grind to move the pushrod over for stock rockers offset or buy offset roller rockers. We are running a set of DC stage IV heads 3614476 clearanced for stock rocker offset. They have a lot of potential but unfortuntionatly lots of port work required if you want them to maximized. They respond to bigger valves and the thick castings are nice. They share similarities with the later 452 and 346 heads on the intake port. A 906 is a little different. My preference would keep with 906s on a a12 car but...the only one that would know likely is someone you told because externally with valve covers on they sure look the same to me. The short side of the intake port on a 906 is higher and is different then a stage IV. Unported I would guess the stage IV would be similiar to the other iron heads. Ours had work done before hand so we never flowed them on the flowbench stock.

 

[Dave6T4]

I always got a kick out of Chrysler bragging about "Magnum" heads on RoadRunner and SuperBee, when they were basically the same head on grampa's Newport

 

[71gtx471]

I think A12 906 heads came equipped with the heavy gauge stamped rockers.