69Ronrunner
Member
what are the diffrence between 68-69 open chambered 906 heads and 64-67 closed 516 heads? which head flows better? has a larger cc chamber? general thoughts
open vs closed
- Thread starter 69Ronrunner
- Start date
Funship32
Well-Known Member
My understanding is as follows: The 915 heads in stock form had a smaller exhaust valves (other than the '67 440) than the 906 heads plus they had smaller combustion chambers w/ more of a 'quench' area. The smaller valve 'issue', if you can call it that, is easily remedied (I had the larger valve put in my 915 heads with hardened seats) but the real advantage is that the 915 heads had more quence and a smaller combustion chamber and that supposedly made more power. I cannot attest to that but that is what I recall reading. As a side note: My understanding is that Chrysler moved to the open chambered heads and the larger exhaust valve more for upcoming emission reasons than for any performance reason. Not that they are bad heads but that was the reason for the change.
516 head - 1964-1967 close chambered head used on all big blocks except the 1967 440, different style ports than the 915/906 head, 2.08/1.60 valves, poorer flow than the 915/906 heads (maybe 15 cfm less on the intake, maybe a little more difference on the exhaust), chamber volume around 84 cc as cast
915 head - 1967 only, all 440s came with this head in 1967. Ports are virtually identical to a 906 head, flow about 230-235 on the intake as cast on the intake side. 84 cc combustion chambers as cast. HP 440s used 2.08/1.74 valves, non HP 440s used 2.08/1.60 valves.
906 head - 1968-1971, all big blocks used this head, ports the same as the 915, all 906s used 2.08/1.74 valves. Open chamber, around 90 cc as cast. The open chamber was for better emissions characteristics.
If you are trying to decide between which to use I would use the 906 head in almost all cases.
915 head - 1967 only, all 440s came with this head in 1967. Ports are virtually identical to a 906 head, flow about 230-235 on the intake as cast on the intake side. 84 cc combustion chambers as cast. HP 440s used 2.08/1.74 valves, non HP 440s used 2.08/1.60 valves.
906 head - 1968-1971, all big blocks used this head, ports the same as the 915, all 906s used 2.08/1.74 valves. Open chamber, around 90 cc as cast. The open chamber was for better emissions characteristics.
If you are trying to decide between which to use I would use the 906 head in almost all cases.
RustyRatRod
Well-Known Member
Matt, I hope you're right on the as cast chamber volume on the 516, but I think you're estimate is a bit on the big side. I hope it's not for my sake. lol
Also the 906's are for 68-70. 71 used the 346 head.
Open cambers suck. Wasted space IMO.
Rusty I just picked up a set of worked 516 heads that I would like your thoughts on. I'll get some pics.
Open cambers suck. Wasted space IMO.
Rusty I just picked up a set of worked 516 heads that I would like your thoughts on. I'll get some pics.
Funship32
Well-Known Member
Here is some more info that is a good read: http://www.moparmusclemagazine.com/...0_mopar_max_wedge_cylinder_heads/viewall.html
- - - Updated - - -
Interesting. I say that as I'd go the other way- I'd use either a 516 or a 915 head IF the engine was setup up for it. But then again, if I was going to go to the expense of getting a block setup for either the open or closed chambered head, I'd probably go with some Source 440 Alum heads and get better flow right out of the box. :icon_winkle:
You are correct, my mistake on the 68-71 quoted date
No worries. That artical is a good read but it states that the 906 was used in 71 which is not true.
RustyRatRod
Well-Known Member
Cool. I got 2 pairs. Gonna spend way too much on one pair, but they'll work for me. lol
Hey Mark, interesting I was actually not taking that info out of the article, just going based on memory. I had thought that the switch to the 346 was mid year 71. I consulted Chuck Senatore's book to be sure you were correct.
Similar threads
