Chevy BB Heads

[farmer tx]

To save me from removing my heads and C.C.ing
them myself, does anyone know the intake runner and combustion chamber volume of factory BB chevy heads on a 86-454 mag oval port engine? If I need to remove a valve cover and get a casting # I don't mind doing that.

Thanks for any help,

[MAXCAT]

If you have a 454 Mag engine. It should have rectangular intake ports. The oval port heads were used on the base marine. Runner volume - 325 cc, chamber volume - 118cc

[farmer tx]

MAXCAT,
It never occurred to me that it would have rec. port heads. I thought most production marine engines used the truck or oval port head. This calls for some investigation. I think I can maybe tell by looking at the intake manifold.

Thanks for the insight,

[turbo2256]

Get the p/n off them you could have the large oval port heads. Which in my opinion work better in the marine world of 5200 RPM.

[MAXCAT]

FRMRTX, GM used the rectangular port heads on the 454 magnum engine as well as the 502. The Base marine engine for that year had the Oval port heads (which are better for low end torque because the high velocity inlet charge). The small oval port heads (sometimes called peanut) port heads were put on the PFI Base Marine engine in 96. A casting number would help, but I am almost certain you already have rectangular port heads.

[farmer tx]

I forgot to include the fact that it is a 330hp
454 mag. Sorry!I looked at the intake and it appears to be a oval port. So my question now is
the cc of the oval port.

Thanks

[Bad-Tat]

Mark,
Does this mean another fast Tx boat at the next gathering???

[farmer tx]

Bill,
I don't have a clue ase to what you mean!
?????

[Scott Pearson]

If its a 330 and has never been messed with, it has oval port heads.

(NJ)Scott

[Jamesbon]

Marine Intakes (Merc.)
The difference between a stock Merc. oval port intake manifold and a stock Merc. rectangle port intake is the height of the carb. mounting flange. The rectangle port intake's carb flange will be a few inches higher than the plane of the manifold, a "high rise" if you will. The oval port intake's carb flange is mounted lower in relation to the plane of the intake.

Combustion chambers
All Merc. BBC heads, rectangular and oval port, maintained the 118 cc combustion chamber, that is until the 7400 Vortech was introduced which uses 105 cc.

Intake port volume (head)
High performance rectangular port heads hold 320 cc's. Semi performance large oval port heads hold 230 cc's. Small low performance oval ports hold 200 cc's.

Pop the valve cover and get the casting number to be absolutely sure. Post it here, and I'll run it...

Hope this helps...

[Looped]

Frmrtx,
If you pop one of the v-covers off you can check for one of these casting #'s and find the volume. Many of these are older but I'm to lazy right now to clean it up.

330864.....68-84...oval...OPEN...396, 402, 366T, 427T, 454 Truck
330865.....68-84...oval...OPEN...396, 402, 366T, 427T, 454 Truck
336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports
343771.....68-86...oval...OPEN...366T, 427T, 454
343772.....68-86...oval...OPEN...366T, 427T, 454
343783.....70-76...oval...OPEN...454 Truck
346236.....75-87...oval...OPEN...454, 120cc chamber, 225/116cc ports
352625.....70-76...oval...OPEN...454 Truck
353049.....73-84...oval...OPEN...454, 122cc chamber, 255/119cc ports
3931063....68-69...oval..CLOSED..396, 402, 427, 101cc chamber
3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber
3933149....68-76...oval...OPEN...427T, 122cc chamber
3935401....68-76...oval...OPEN...427T
3946074....69&71...rect...OPEN...'69 427 L88, ZL1, Aluminum, 118cc chamber '71 454 LS6, "round exhaust port"
3964290....69-70...oval..CLOSED..396, 402, 427, 454, 101cc chamber Large or small hex spark plugs used
3964291....69-70...rect..CLOSED..396, 402, 427, 454, 109cc chamber
Large or small hex spark plugs used
3986133....68-85...oval...OPEN...366T, 427T, 454 Truck
3986136....68-84...oval...OPEN...366T, 427T, 454 Truck
3993820....71-84...oval...OPEN...454 Passenger and Trucks, 113cc chamber, 255/114 ports
3994026....71......rect...OPEN...454 LS6, 118cc chamber
3999241....72......oval...OPEN...402, 454, 113cc chamber
6272292....70-78...oval...OPEN...402, 454
6272990....70-up...rect...OPEN...454 service replacement, used on some MKIV crate engines, 118cc chamber
10114156...91-up...oval...OPEN...Gen.V & VI 454, 118cc chamber
10141279...96-up...oval..CLOSED.."Vortec 7400", 100cc chambers
10487052...77-90...oval...OPEN...366T
12363391...96-up...oval...OPEN...Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI, 110cc chamber
12363401...96-up...rect...OPEN...Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI, 118cc chamber
12560241...98-up...oval..CLOSED.."Vortec 7400", 100cc chambers
14011077...69-up...rect...OPEN...Aluminum, fits MKIV, "C-port"
118cc chamber, also sold as a "solid" head
14044861...84-96...rect..........Bowtie, Aluminum, MkIV,
"raised runners", 1st design, 105cc chamber
14044861...96-up...rect..........Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI "raised runners", 2nd design, 115cc chamber
14044861...84-96...rect..........Bowtie, Aluminum, MkIV
"raw" casting of "861" MKIV 1st design
14081045...78-87...oval...OPEN...454
14081052...85-87...oval...OPEN...366T, 427T, 454 Truck, Marked "HiPerf"
14092360...86-88...oval...OPEN...454 Truck
14096188...70-71...rect...OPEN...454 service replacement, also used on later Mark IV LS-6, LS-7 and 454 HO crate motors, 116cc chamber
14097088...91-up...rect...OPEN...Gen.V 454/502 HO, 118cc chamber


If it's one of the ones on the bottom that does not have a "cc" I can track it down for you.
Craig

[farmer tx]

Thanks Looped,
I'm going to pull a valve cover this afternoon
and get a casting number.

[farmer tx]

Craig,
Well finally got around to removing exhaust manifolds today, and took a valve cover off. Seems the stock heads are #14081045 oval port.
Im wanting to go with the #12363391 heads if they wont lower my compression ratio.
The intake runner on the #12363391 is 290cc and the combustion chamber is 110cc like you listed.
Patiently waiting for my S.M. exhaust.

[roadtrip se]

Mark you need to get back out there in the fields!
Rain is supposed to finally stop here tomorrow.
Get that crop in, so you can really start messing around with that motor!

So what exactly are you up to my friend? Something tells me we got a little more going on than just some shiny new headers... eek!

AOTH3 is seven months out, plenty of time to put together a West Texas dynamo! cool!

Need more info and your secret ISN'T safe with me.

Todd

[farmer tx]

Tod
Just thinking about some upgrades.Giving me somthing to do on these long wet days. Didn't know if you were back in Texas yet. I'll try to give you a call soon.
Untill then,