383 heads

[jeff deakins]

Casting Number on heads are 3462346 are these considered 906 heads or something different
Thanks

 

[dadsbee]

Let me go read the numbers on my polisher counter weight...

...oh found another shot. They're called "906" heads because that's the end of the part number. 2843906

 

[PurpleBeeper]

Those would be "346" heads & considered good ones, very similar to "906" heads. They are listed from '71-'73. I "think" sometime about 1973 they started hardening exhaust valve seats (considered a good thing). I have 346 heads on my Roadrunner right now.

 

[jeff deakins]

Thanks

 

[Jerry Hall]

If I'm not mistaken, 346's are the same as 906's with hardened seats. I had a 72 RR GTX 440 with 346 heads.

 

[Kernel Sanders]

I'm going to start keeping an eye open for 346's then because I thought the 452's were the only ones with induction hardened exhaust seats for unleaded fuel use.

 

[69Bee]

FYI, these heads are quite old now, and the seat hardness will likely be gone or partial from repeated valve jobs. 906, 346, and 452 heads are dimensionally the same, but the latter two got induction hardened seats, and smog features. Do yourself a BIG favor, and have exhaust seats put in when you have whatever heads you get machined.

 

[Don Frelier]

I've run 906 heads on my 383 from a 70 for 22 years and over 30,000 miles. No issues with exhaust valves. The 50 year old iron is quite hard.

 

[dadsbee]

..and they've been work hardened by now anyhow Don. I'm in the same boat, my 383 Magnum was rebuilt in 1979. Still runs like a top. I also replaced all the valve seals before I painted to reinstall last year and gave all valves the "wobble test" and they're good to go. I always ran a bit of lead additive when lead was phased out and now run a 10 to 20% 100LL AV Gas to Shell 93 mix just to be safe.

 

[PRHeads]

If I'm not mistaken, 346's are the same as 906's with hardened seats. I had a 72 RR GTX 440 with 346 heads.

You would be mistaken.

There are no BB heads that are “the same” as 906 heads.
The 906 head is the best flowing and has the largest as cast intake runner volume of any of the open chamber heads that came in vehicles.

The later heads are “interchangeable” with 906’s........ but they aren’t the “same”.

 

[69Bee]

..and they've been work hardened by now anyhow...

That's not how it works, and once they start digging, they won't stop until the spring is loose. Mopars tend to do better due to a higher nickel content, BUT for $125 when the heads are being worked on is cheaper than having to go back in and do it the second time.

 

[dadsbee]

Yah okay, like I said.. 40 years since rebuild and runs just fine! If I had it apart of course, but there's no point at this stage of the game. The original OP's question was "are these 906 heads". They are not and as pointed out they don't have the flow of 906 heads...

 

[Garys1969RR]

Does the 915 flow as well as the 906 head? I heard they had the same port shape and size, just that the 915 is a closed chamber head. Is that right ? Same ports?

 

[Bee1971]

Good arcticle

http://www.moparts.org/Tech/Archive/bb/62.html

Another


https://www.hotrod.com/articles/cylinder-heads/

 

[PRHeads]

The 906 and 915 have the same intake port shape.
The 915 has a slightly different ex port than any of the other castings I’ve seen.

 

[Cranky]

They are pretty dang close that it doesn't make a much of a difference in stock form but you can also take any number of the same part number head and still get different flow numbers. It just depends on the quality of the casting. The worse part of a stock head is the undercut or valve pockets. Just porting that area will usually make any of them flow much better.....