Small Block Cylinder Heads 'Stock Specs'

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69 Cuda 440

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Small Block Cylinder Heads

CC's / Port Volume / Size / Flow

1966 - 1967 {273} Casting #2658920

Heart-Shaped Combustion Chamber

Factory CC Level..........................62.0 to 65.5 CC's
Recommended Minimum CC's......57.3 CC's

Intake Port Gasket Size...............1.05" x 2.07"
Exhaust Port Gasket Size.............1.14" x 1.59"

Intake Valve................................1.78"
Exhaust Valve..............................1.50"

Intake Bowl Size.........................1.53" {86% of Valve}

Intake Port.................................125 CC
Exhaust Port...............................61 CC

Intake Flow...............................160 CFM @ .450" Lift
Exhaust Flow.............................107 CFM @ .450" Lift

Intake-to-Exhaust Flow.............64.8%

Small Block Cylinder Heads

CC's / Port Volume / Size / Flow

1968 - 1971 {340} Casting #2531984 'X-Heads'

Open-Shaped Combustion Chamber

Factory CC Level..........................65.0 to 69.0 CC's
Recommended Minimum CC's......63.5 CC's

Intake Gasket Port Size..............1.16" x 2.27"
Exhaust Gasket Port Size............1.25" x 1.75"

Intake Valve..............................2.02"
Exhaust Valve............................1.60"

Intake Bowl Size........................1.75" {87% of Valve}

Intake Port Size........................160 CC
Exhaust Port Size.......................70 CC

Intake Flow.............................215 CFM @ .450" Lift........221 CFM @ .500" Lift
Exhaust Flow...........................140 CFM @ .450" Lift........142 CFM @ .500" Lift

Intake-to-Exhaust Flow....................65.5%..............................64.1%.............

Small Block Cylinder Heads

CC's / Port Volume / Size / Flow

1970 {340 T/A} Casting #3418915 'J-Head'

Open-Shaped Combustion Chamber

Factory CC Level...........................68.0 to 73.0 CC's
Recommended Minimum CC's.......63.5 CC's

Intake Gasket Size.......................1.16" x 2.27"
Exhaust Gasket Size.....................1.25" x 1.75"

Intake Valve................................2.02"
Exhaust Valve..............................1.60"

Intake Bowl Size..........................1.75" {87%}

Intake Port Size...........................157 CC
Exhaust Port Size..........................73 CC

Intake Flow.................................213 CFM @ .450".........220 CFM @ .500" Lift
Exhaust Flow...............................146 CFM @ .450".........148 CFM @ .500" Lift

Intake-to-Exhaust Flow.......................68.8%............................67.3%..........

Small Block Cylinder Heads

CC's /Port Volume / Size / Flow

1968 - 1974 {273 & 318} Casting #2843675

Open-Shaped Combustion Chamber

Factory CC Level.........................67.0 - 68.5 CC's
Recommended Minimum CC's.....60.6 CC's

Intake Gasket Size....................1.05" x 2.07"
Exhaust Gasket Size..................1.14" x 1.59"

Intake Valve..............................1.78"
Exhaust Valve............................1.50"

Intake Bowl Size.......................1.53" {86%}

Intake Port Size........................127 CC
Exhaust Port Size........................61 CC

Intake Flow...............................160 CFM @ .450" Lift...........162 CFM @ .500" Lift
Exhaust Flow.............................107 CFM @ .450" Lift...........109 CFM @ .500" Lift

Intake-to-Exhaust Flow......................66.8%...................................67.1%..........

Mope-Kid D-3

Results coming u,,,,,,,,,,,

Casting #530006671

stockmagnum.jpg


1992 - 2004 {318 Magnum} Casting #53006671 {Also Casting #'s 671/466/714}

CC's / Port Volume / Size / Flow

Closed-Chamber Combustion Chamber

Weight......................................62 lbs.

Factory CC Level.......................60.0 to 66.0 CC's
Recommended CC Level............60.0 CC's

Intake Port Gasket Size.............1.18" x 2.18" (Actual Port Size = 1.08" x 2.075"}
Exhaust Port Gasket Size...........1.08" x 1.80"

Intake Valve..............................1.920"
Exhaust Valve............................1.625"

Intake Bowl Size.......................1.65" {86%}

Intake Port Volume...................153 CC
Exhaust Port Volume...................64 CC

Intake Flow..............................193 CFM @ .450" Lift........199 CFM @ .500" Lift
Exhaust Flow............................147 CFM @ .450" Lift........149 CFM @ .500" Lift

Intake-to-Exhaust Flow......................76.5%..............................75%..............

(Trouble posting pics, will try again)
I have a very early, first year 340 bare block with caps. Spring of 2021 I had it fully checked out, had one cylinder sleeved on the original bore, machined .030 over, align bored, etc, etc Have the receipt from Domhoff’s in Harmony, PA. Cast in June of 1967, this has to be one of the very first 340 blocks to come out of the Foundry. I found the #’s at the deck surface just beneath the left head, but the #’s at the back of the block (vin?) isn’t real legible and there are no #’s at the pan rail. A super-find for someone doing a period correct ‘68 Dart or Barracuda resto. I do not have a crankshaft but a friend has one that may be willing to part with for a reasonable price. I’m asking $2500 for the block and will be more flexible if you’re interested in the heads...

Also have a pair of bare X heads. These were checked out, but no machine work done. No valves or springs, but I do have rocker shafts and adjustable rocker arms and maybe a set of cup pushrods. Asking $700 for the heads....available only if I sell the block.

I don’t want to ship, but may consider delivery to Chry/Carlisle
I’m just north of Pittsburgh. Just off Interstate 79 and PA Turnpike. 30 min from I-80.
Thanks FABO!

Finally-pics…sorry !

D92CC301-CDF0-4922-B0C4-49D3D81446D5.jpeg


09F640A2-1FED-4BD6-9A1C-2C8C0857F94E.jpeg


453E7C55-6514-4E3C-A548-F3F5FFA7CAC3.jpeg


27A5F069-EF4F-42DC-8435-2D4265D27175.jpeg


57DA59B9-6E46-4419-A80B-8C5B00E15423.jpeg


921842A8-2805-4E65-8789-36485484AE11.jpeg


DCA4835C-7C98-4EA3-84B4-45F79783EAD8.jpeg


E82E1F8F-A559-496E-BE2D-AEA557030CFB.jpeg


7C12E737-BD2F-4C7C-9D5C-38739BAED040.jpeg


4D827EE9-D65C-4C24-AF5E-AE95485A7D30.jpeg
 
Last edited by a moderator:
Sounds about right by my experience. Took .040 to get the largest chamber just above min cc. Mine must have been closer to 61cc.
 
Aren't J heads supposed to be the same chamber as X heads? I know they're folks on here who've cc'd their J heads at 72 or more
 
Correct TX-Stang-84,

The #3418915 'J-Heads'

'J-Head' Combustion Chambers are typically at 68.0 - 72.0 CC's.

Also, the Intake Port with the 2.02" Valves has measured as much as 3 CC's less than the
'X-Heads' {157 to 160 CC's}.

But, the Exhaust Ports on the 'J-Head" have measured as much as 3 CC's larger than the
'X-Heads" {73 to 70 CC's}.

Port wise, they are nearly identical, with a very minor variation in Port Volume.

I'll post the 'J-Head' specifications later.
 
69 Cuda 440 said:
Small Block Cylinder Heads

CC's / Port Volume / Size / Flow

1966 - 1967 {273} Casting #2658920

Heart-Shaped Combustion Chamber

Factory CC Level..........................61 to 63 CC's
Recommended Minimum CC's......57.3 CC's

Intake Port Gasket Size...............1.05" x 2.07"
Exhaust Port Gasket Size.............1.14" x 1.59"

Intake Valve................................1.78"
Exhaust Valve..............................1.50"

Intake Bowl Size.........................1.53" {86% of Valve}

Intake Port.................................125 CC
Exhaust Port...............................61 CC

Intake Flow...............................165 CFM @ .450" Lift
Exhaust Flow.............................107 CFM @ .450" Lift

Intake-to-Exhaust Flow.............64.8%
Click to expand...

Thanks for that info. I too had to shave quite a bit to get down to the 57 cc range. If I was to do it over I would at least go 1.80/1.60 valves. tmm
 
69 Cuda 440 said:
1968 - 1971 {340} Casting #2531984 'X-Heads'

Open-Shaped Combustion Chamber

Factory CC Level..........................65.0 to 68.0 CC's
Recommended Minimum CC's......63.5 CC's

Intake Gasket Port Size..............1.16" x 2.27"
Exhaust Gasket Port Size............1.25" x 1.75"

Intake Valve..............................2.02"
Exhaust Valve............................1.60"

Intake Bowl Size........................1.75" {87% of Valve}

Intake Port Size........................160 CC
Exhaust Port Size.......................70 CC

Intake Flow.............................215 CFM @ .450" Lift
Exhaust Flow...........................140 CFM @ .450" Lift

Intake-to-Exhaust Flow...........65.5%
Click to expand...

I checked an untouched 69 X head just out of curiosity last winter and the combustion chambers were 68-69 cc and they flowed 235/150 @ .500 so these #s sound rite to me...
 
The factory 2.02 j heads I have tested flow 228cfm intake and 142-147cfm exh.
The factory 2.02 j heads also have an exact 72 cc chamber.
The port volume increases from 160 to 165 with a 1.88 int valve due to the back side of the valve head having less tulip to it.
The 1.88 int valve j head flows 215cfm .450-.500

The 318 heads can be 124-125cc int port volume, the open chamber version is 68 cc while the closed is only a few cc smaller amazingly enough at 65-66cc.

The specs I give come from stock/as cast heads from 64-71.
 
The 'Combustion Chamber' CC's measurements seem to bounce around
a lot on the Small Block Mopar Heads.

I have a #2658920 Head {untouched} that measured at 62.6 CC's, and another
#2658920 Head {untouched} that measured at 65.1 CC's.

As per the normal milling procedure, .0065" has to be 'milled' off the Head to
reduce 1 CC level.
 
66fs said:
Chrysler says .0053 of an inch to reduce 1 cc of chamber volume on 273 / 318. heads. I remember being impressed at how dead on that was.
Click to expand...

I believe that is for the 1968 and later 'open chamber' 273/318 Cylinder Heads.

1967 and earlier [Heart-Shaped/Closed Chamber} Cylinder Heads require
a 'smidge' more removal to reduce 1 CC level.
 
I've never cc'd open chambered heads, except J heads. I'll stick with the factory numbers since I've verified them myself. Thanks for all your Info.
 
If ur quoting this guy, next time use quotations...cause it clearly reads "you must not know **** about heads, I know better"

Kinda pissed me off because you and I usually agree or get along...and today is one of those days I could *** rape someone with their own arm while beating them over the head with their other.

If I'm missunderstood your pm, my appologies.
 
This a general information thread,

Your results may vary.

These results were performed on sets of Cylinder Heads that we had in our
storage bin, 'Stock' unmolested Cylinder Heads.

The 1968 thru 1974 #2843675 Cylinder Heads that we tested had a 'tad'
greater port volume level at 127 CC's.

Does it really matter '1 Wild & Crazy Guy'.
 
If none of this is accurate , wether it farse info by you or anyone else or if people have to test to find out...then they can just look in those books and get the same inconsistant specs given here

People this is not completely accurate, its close, some of it anyways...but just test yourself.
 
1wild&crazyguy said:
If none of this is accurate , wether it farse info by you or anyone else or if people have to test to find out...then they can just look in those books and get the same inconsistant specs given here

People this is not completely accurate, its close, some of it anyways...but just test yourself.
Click to expand...
------------------------------------------------------------------------------

So what you're saying is,

That if you have '2' sets of 'identical' Cylinder Heads and pop them on the same
Small Block Mopar Engine, they will give the same 'exact' output without any variance + or -.

Who are you kidding..........
 
Do you have any factory magnum heads to flow test? I'm interested in seeing the intake:exhaust flow ratio... this thread shows why dual-pattern cams are a good idea on LA heads
 
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