906 heads

[freshayr]

I want to buy a 440 to rebuild to put in my 68 Coronet. This is just a street car..not a racer. I have found 2, one is a 68 and one is a 72. both have 906 heads. Are the 906 heads a good head?

 

[69 Runner]

The 906 is the casting used on all the big blocks from 68-71 (possibly some used a bit later) Do NOT be misled, there is NO SUCH THING as a "Magnum" head (I.E. what was used on say a 383 Magnum road runner motor)

Let me repeat. They are all the same casting. A 383 2 barrel and a 440 Six Pack used the exact same head casting.

All that said, if what you're building is a "driver" it really doesn't matter if you use 906s, 346s, or 452s. What you will want to have done is have hard exhaust seats installed, and it would be a good idea to have bronze guides (or at least inserts) installed as well. This will just help your motor live on the crappy gas we have to use these days.

Also, since you're going to rebuild the motor anyway it doesn't make much difference what year you use (unless you don't want a cast crank motor so don't get one with the fat balancer)

An "HP" motor is an "HP" only because of the compression ratio, cam, valve springs, carb tuning, distributor timing and advance, and exhaust manifolds. So if you find a smokin hot deal on a 440 that "isn't an "HP"' motor, don't pass on it. You're going to replace everything in the motor that made in an "HP" motor during the rebuild anyway, so it doesn't matter.

Hope this helps

 

[66_B_Body4ever]

I was unable to find part 1 of this article, but it will help you make up your mind which set to use. This shows part 2 of the article...

http://www.moparmusclemagazine.com/techarticles/5118_cylinder_heads_ii/index.html

Cheers!

Here's the first editorial I believe

http://www.moparmusclemagazine.com/images/mopp_0608_mopar_cylinder_heads/index.html

 

[Patrick]

The 906 is the casting used on all the big blocks from 68-71 (possibly some used a bit later) Do NOT be misled, there is NO SUCH THING as a "Magnum" head (I.E. what was used on say a 383 Magnum road runner motor)

Let me repeat. They are all the same casting. A 383 2 barrel and a 440 Six Pack used the exact same head casting.

All that said, if what you're building is a "driver" it really doesn't matter if you use 906s, 346s, or 452s. What you will want to have done is have hard exhaust seats installed, and it would be a good idea to have bronze guides (or at least inserts) installed as well. This will just help your motor live on the crappy gas we have to use these days.

Also, since you're going to rebuild the motor anyway it doesn't make much difference what year you use (unless you don't want a cast crank motor so don't get one with the fat balancer)

An "HP" motor is an "HP" only because of the compression ratio, cam, valve springs, carb tuning, distributor timing and advance, and exhaust manifolds. So if you find a smokin hot deal on a 440 that "isn't an "HP"' motor, don't pass on it. You're going to replace everything in the motor that made in an "HP" motor during the rebuild anyway, so it doesn't matter.

Hope this helps

It was 68 when the B, RB engines went to a common head. Before that the 350,361, 383, 383 RB used a head with smaller ports and valves than a 413 or 440 RB. Also the 426 MAX WEDGE had its own heads with monster ports.

 

[69 Runner]

True. And while a lot of the earlier 383s (and 361s) had 516 heads and the 67 440s had 915, which supposedly had the same valves as a 906 and later, not all did.

Not only that, but there are racers out there that seem to think the 516s are better for hogging out than practically anything else.

 

[Meep-Meep]

906's are great heads and share the same port floor as the 915, which are considered the best production heads by design (I know Max heads have huge ports but I believe the ports are not as efficient with the flat floor). I prefer 915's because of the closed chamber to promote swirl and reduce detonation, but the advent of quench dome pistons allows for superior closed chamber type combustion characteristics of any open chamber head. Hard seats will be mandatory for unleaded gas. The late flat floor heads (452, 346) have been known to produce good results, so I guess weigh the cost vs perf options to update the 906 or just go with the later induction hardened stuff.

...and yeah, anyone who claims that 69 440 magnum HP six pack heads are better than 69 383 2 BBL heads is pulling your third member!!

 

[beeguy]

I would without a doubt go with the '68 engine because your car is a 68. sure it's not the original engine but it's as close as you can get, I always look for a proper date code no matter what it just doesn't cost that much to do it .