906 or 915 ?

44o gts dart

Well-Known Member
Joined
Sep 28, 2014
Messages
122
Reaction score
47
Location
iowa
Quick question for all you knowledgeable people,,,, I am building a mild 440 for my dart,hoping for 450 horse. ,I have a virgin pair of open chamber 906’s that came with block,that I have to redo ,,,, but know of a set of ported and polished 915’s off a 67,,, stainless 2.14 and 1.8 valves,.HD springs, titanium retainers… which would YOU use… and what would be a fair price for the 915’s ( which were just pulled off a running engine ) thanks in advance

2E945A11-5950-45D3-9C98-4BAFB072FEBB.png
 

RustyRatRod

I was born on a Monday. Not last Monday.
FABO Gold Member
Joined
Jun 7, 2010
Messages
91,975
Reaction score
79,566
Location
Georgia
DO the 915s come with flow numbers? The 906s if redone and ported will be the devil you know, versus the devil you don't know.
 

1WildRT

Well-Known Member
Joined
Aug 13, 2021
Messages
410
Reaction score
698
Location
Modesto Ca
I like the 915's but I choose my piston based on the 915's... The wrong piston could make them a very bad choice...
 

PROSTOCKTOM

Well-Known Member
Joined
Oct 8, 2013
Messages
446
Reaction score
309
Location
West Central Indiana
In my opinion you do not need 915 heads or even larger valves to make 450 HP. It all boils down to your budget and how you want to make the power. Get yourself an Edelbrock Performer RPM intake and you'll already have a huge start on the 450 number.

Tom
 

roccodart440

Well-Known Member
Joined
Apr 19, 2010
Messages
6,634
Reaction score
3,216
Here is a recipe for [email protected],600 RPM

906 heads (blueprinted, 2.14 / 1.81, Stage 1 port)
10.5:1 comp dome pistons for 88cc chamber
Performer RPM intake
825 holley
284/.528/112 soilid
1.6 ratio rockers (yields .556 lift)
2.125 full length headers
 

44o gts dart

Well-Known Member
Joined
Sep 28, 2014
Messages
122
Reaction score
47
Location
iowa
DO the 915s come with flow numbers? The 906s if redone and ported will be the devil you know, versus the devil you don't know.
I asked him if he knew that number, but he did not. He said he just pulled them off his 383 bracket duster racer that was running 10.70’s. He is going aluminum… they are 3 hrs away so I have to figure another 150 in fuel,, he had them listed for 1200 almost 2 weeks ago,,down to 1k now,,, money is always tight on my end, so I was gonna offer 750 and I pick up,,,I assume I will have that in my 906’s for hardened seats, a good valve job and ports matched…. They are probably worth 150,, 1969 casting numbers( they been cleaned, mag crack checked,, new brass freeze plugs..I am leaning on staying with my 906’s,, my 1969 block will get deck, squared, bored and line bored, balanced rotating assembly… I just want a powerful , reliable,, stock looking engine… in a original m code dart.
 

496 polara

moparts id gch
Joined
Feb 23, 2014
Messages
604
Reaction score
747
Location
North Carolina
I would have either set checked over. Unless the 915's are a deal (like $500-600) and check out good (don't need any work) I would price out what it will take to get the 906 heads ready to run.

You may find it cheaper to buy a set of 440 source heads and be farther toward your hp goal. Even if you go that route have them checked out.Don't just assume they are ready to run.
 

44o gts dart

Well-Known Member
Joined
Sep 28, 2014
Messages
122
Reaction score
47
Location
iowa
I asked him if he knew that number, but he did not. He said he just pulled them off his 383 bracket duster racer that was running 10.70’s. He is going aluminum… they are 3 hrs away so I have to figure another 150 in fuel,, he had them listed for 1200 almost 2 weeks ago,,down to 1k now,,, money is always tight on my end, so I was gonna offer 750 and I pick up,,,I assume I will have that in my 906’s for hardened seats, a good valve job and ports matched…. They are probably worth 150,, 1969 casting numbers( they been cleaned, mag crack checked,, new brass freeze plugs..I am leaning on staying with my 906’s,, my 1969 block will get deck, squared, bored and line bored, balanced rotating assembly… I just want a powerful , reliable,, stock looking engine… in a original m code dart.
 

RustyRatRod

I was born on a Monday. Not last Monday.
FABO Gold Member
Joined
Jun 7, 2010
Messages
91,975
Reaction score
79,566
Location
Georgia
I asked him if he knew that number, but he did not. He said he just pulled them off his 383 bracket duster racer that was running 10.70’s. He is going aluminum… they are 3 hrs away so I have to figure another 150 in fuel,, he had them listed for 1200 almost 2 weeks ago,,down to 1k now,,, money is always tight on my end, so I was gonna offer 750 and I pick up,,,I assume I will have that in my 906’s for hardened seats, a good valve job and ports matched…. They are probably worth 150,, 1969 casting numbers( they been cleaned, mag crack checked,, new brass freeze plugs..I am leaning on staying with my 906’s,, my 1969 block will get deck, squared, bored and line bored, balanced rotating assembly… I just want a powerful , reliable,, stock looking engine… in a original m code dart.
The 906s flow better. I know which ones I'd use.
 

PRH

Well-Known Member
Joined
Dec 14, 2018
Messages
4,363
Reaction score
6,527
Location
So. Burlington, Vt
Unless you can be “all in” on the iron heads for way less $$$ than a set of stealths....... now would be the time to make the move away from the stock heads.
 

413

Well-Known Member
Joined
Nov 13, 2019
Messages
853
Reaction score
1,500
Location
NW USA
Buried in his post, “stock looking engine, these are going on an original m code dart” that’s a factory 440 DART SWINGER. so I bet iron heads are what he wants.

use the 906 heads. Are you using stock manifolds? Then you don’t need oversized valves.

remember this, It’s all about the combination.
 

44o gts dart

Well-Known Member
Joined
Sep 28, 2014
Messages
122
Reaction score
47
Location
iowa
Buried in his post, “stock looking engine, these are going on an original m code dart” that’s a factory 440 DART SWINGER. so I bet iron heads are what he wants.

use the 906 heads. Are you using stock manifolds? Then you don’t need oversized valves.

remember this, It’s all about the combination.
No,,, I will run under chassis headers… have only left hand manifold but I realize they are too restrictive,,, have spoke to the original owner and when he put fender well headers on it ,,,,, it way way stronger,,,, it’s a rare m code 440 gts
 

roccodart440

Well-Known Member
Joined
Apr 19, 2010
Messages
6,634
Reaction score
3,216
I'll see if I can dig it up. This was some 20+ years ago, back when bigblockdart.com still existed, or was at least active.

It was this engine. Note the POS Indy dual place sitting on top of it.

00W0W_d96RxFeRnsJ_600x450.jpg
 

PRH

Well-Known Member
Joined
Dec 14, 2018
Messages
4,363
Reaction score
6,527
Location
So. Burlington, Vt
Here’s one from about 25 years ago:

446
Trw L2266’s
Bowl blended 906’s, 2.14/1.81
Torker with Demon 650
General Kinetics version of a Comp 280H
1.6/1.5 rockers
1-7/8 x 3 headers

F41AB01A-57A4-4316-BA36-8A617EA77882.jpeg
 

PRH

Well-Known Member
Joined
Dec 14, 2018
Messages
4,363
Reaction score
6,527
Location
So. Burlington, Vt
915’s and 906’s have the same intake port.
The ex ports are slightly different, and IMO the 906 port is the better of the two.
The closed chamber of the 915 gives it the overall edge though.

That being said, if I didn’t have a suitable set of 915 castings sitting on the shelf........ I wouldn’t pay the premium most seem to be asking for them.
 
Last edited:

RustyRatRod

I was born on a Monday. Not last Monday.
FABO Gold Member
Joined
Jun 7, 2010
Messages
91,975
Reaction score
79,566
Location
Georgia
915’s and 906’s have the same intake port.
The ex ports are slightly different, and IMO the 906 port is the better of the two.
The closed chamber of the 915 gives it the overall edge though.

That begin said, if I didn’t have a suitable set of 915 castings sitting on the shelf........ I wouldn’t pay the premium most seem to be asking for them.
But don't forget there are two 915 castings. There is also the standard 915 with the smaller exhaust valve. Their ports are not as large too, if I'm not mistaken.
 

MOPARMAGA

FABO Gold Member
FABO Gold Member
Joined
Aug 20, 2019
Messages
5,446
Reaction score
5,411
Location
Yakima Wa
Here’s one from about 25 years ago:

446
Trw L2266’s
Bowl blended 906’s, 2.14/1.81
Torker with Demon 650
General Kinetics version of a Comp 280H
1.6/1.5 rockers
1-7/8 x 3 headers

View attachment 1716016184
That's not bad considering those Pistons usually net around 9.3:1 compression and that's a cam you can run a stock converter with and not much lift about .514 with a 1.6 rocker.
I wonder how necessary the 1.81 exhaust valve is in a factory cast iron head, my wondering comes from trickflow using a 1.78 ex valve. With a 2.190 intake valve
I'd think going bigger on the intake would be the ticket. ( Trickflow vs factory 906 ports not a fair comparison) but just a thought
 

NoCar340

The Original Partstitute
Joined
Oct 23, 2022
Messages
49
Reaction score
47
Location
Upper Peninsula MI
But don't forget there are two 915 castings. There is also the standard 915 with the smaller exhaust valve. Their ports are not as large too, if I'm not mistaken.
I think you're thinking of the 516 heads, which are closed-chamber but have smaller exhaust valves and restrictive ports compared the 915s. I can't say I've seen/heard of a 1.60" exhaust 915, but I'm not into big blocks like I once was. If there is, though, I'd assume it's the same situation as LA 915 J heads: The only difference between 340 and 360 casting is the machining. The castings are identical.
 

PRH

Well-Known Member
Joined
Dec 14, 2018
Messages
4,363
Reaction score
6,527
Location
So. Burlington, Vt
But don't forget there are two 915 castings

I’ve never noticed any difference in the castings themselves.
They’re either machined for 1.6 or 1.74 valves(just like SB J heads can be 1.88 or 2.02, but they start out as the same casting).
 
Top