906 Heads

[73RRSunroof]

I pulled my valve covers and found my 440 has 906 heads. Did these heads come on engines that were not stamped hp? Any idea what the backwards upside down B and 1 are for?

 

[Badvert65]

The '906' heads were the standard head casting for all RB and B engines from 68-72(ish). They are good heads and were used on everything from 383 2-bbl engines up to and including the 440-6bbl engines. No difference in the heads. The cam, crank, pistons, etc are what made the differences. The 906 heads are good heads but having them on your particular engine does not have anything to do with whether you have an HP engine or not.

 

[73RRSunroof]

Ok, I read somewhere the heads were what defined the HP. Thanks!

 

[Badvert65]

The 906 heads really woke up the B/RB engines as they had bigger valves than the 67 and earlier heads. The '915' heads were essentially the early heads with the bigger valves, and used on the HP engines only in 1967. In 68, all the B/RB heads (906) got the bigger valves (and a larger combustion chamber). The larger valves were in all big block heads after 68, but there are other differences (casting numbers) such as hardened valve seats, revised port shapes, etc. over the subsequent years. You really can't go wrong with any big block head from 68 on. The heads were only one part of the overall combination. Basically, if you have an 'HP' engine, you will have 906 heads, but having 906 heads does not necessarily mean you have an HP engine. What defined an engine as 'HP' was the intake, cam, pistons, etc that made up the rest of the combination.

 

[dadsbee]

..are there double springs in them?

 

[Badvert65]

..are there double springs in them?

Again, this depended on what the heads were installed on. They could have single springs, with or without a damper spring, heavy duty springs, etc. It really depended on when the engine was assembled and for what application.

 

[dadsbee]

I fully understand that, the question was for the OP !

 

[Challenger340]

2843906 Heads were used on all 1968 to 1970 BB Engines, castings are all the same "HP" and NON hp Engines, hp 906 head Engines merely had better V/Springs.

906 Open Chamber Intake Port is a High short side floor, with 2.08" Intake Valve the same Valve as the 1967 "915" Closed Chamber Head, which was the only High Intake Port floor Closed Chamber Head(same as the 906), the earlier Closed Chamber castings all being LOW Intake Floor ports.
The Exhaust Ports on the 906 and 915 are slightly different from each other, but similar Flow.
ALL BB Mopar Heads(except max Wedge) used a common 1.60" Exhaust Valves, except the "HP" version 915's starting in 1967 had the 1.74" Exhaust Valves, which by 1968 and the introduction of the 906 the 1.74" Exhaust Valve became std on all BB heads hp or non hp.

Head / Year / Engine / Chamber / Intake Port Floor / Valve Sizes
________________________________________________________________________________
2406516 / '66 &'67 / 383 / Closed / Low / 2.08"/1.60"

2780915 / '67 / 440 / Closed / High / 2.08"/1.60"
2780915 / '67 / 440HP / Closed / High / 2.08"/1.74"

2843906 / '68-'70 / 383 & 440 / Open / High / 2.08"/1.74

LOTS of other Castings earlier and later, 250's and 346,452, just trying to show the transitions in Valves & Ports specifically between '66 Closed Chambers to the introduction of the Open Chamber 906's in 1968

 

[PGio]

2843906 Heads were used on all 1968 to 1970 BB Engines, castings are all the same "HP" and NON hp Engines, hp 906 head Engines merely had better V/Springs.

906 Open Chamber Intake Port is a High short side floor, with 2.08" Intake Valve the same Valve as the 1967 "915" Closed Chamber Head, which was the only High Intake Port floor Closed Chamber Head(same as the 906), the earlier Closed Chamber castings all being LOW Intake Floor ports.
The Exhaust Ports on the 906 and 915 are slightly different from each other, but similar Flow.
ALL BB Mopar Heads(except max Wedge) used a common 1.60" Exhaust Valves, except the "HP" version 915's starting in 1967 had the 1.74" Exhaust Valves, which by 1968 and the introduction of the 906 the 1.74" Exhaust Valve became std on all BB heads hp or non hp.

Head / Year / Engine / Chamber / Intake Port Floor / Valve Sizes
________________________________________________________________________________
2406516 / '66 &'67 / 383 / Closed / Low / 2.08"/1.60"

2780915 / '67 / 440 / Closed / High / 2.08"/1.60"
2780915 / '67 / 440HP / Closed / High / 2.08"/1.74"

2843906 / '68-'70 / 383 & 440 / Open / High / 2.08"/1.74

LOTS of other Castings earlier and later, 250's and 346,452, just trying to show the transitions in Valves & Ports specifically between '66 Closed Chambers to the introduction of the Open Chamber 906's in 1968

@ Challenger340 Well done explanation and chart! Thank you for it!

 

[451Mopar]

If using them, the exhaust seats are not hardened for unleaded gas. Should use a gas additive or have hardened seats installed.
It's fairly common to rebuild with larger 2.14"/1.81" valves when porting the heads for performance.

 

[Dave6T4]

The 1968 440 in my 1967 R/T has "906" heads on it. So far, it as 70,000 miles on it since rebuild in 1990. It does not have hardened valve seats like "452" heads. I do not use those gasoline additives, and it still runs fine. My car lives a pretty easy life, of cruising and car shows, however.