Rect port head casting number 3964291 - Team Camaro Tech
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post #1 of 9 (permalink) Old Feb 7th, 10, 11:09 AM Thread Starter
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dave
 
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Rect port head casting number 3964291

these heade are date coded a70 and f70. ive been to different sites and im getting alot of different answers.
with all the infinite wisdom on this site i want to ask opinions of this head?
could it be a ls6 head? a l78 head? or something totally different?
i plan on using these on a 66 396...
any info would be great...thank-you

80 z-28 with a big block....someday i will finish.[sigh] someday
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post #2 of 9 (permalink) Old Feb 7th, 10, 11:41 AM
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Ron
 
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Re: rect port head casting number 3964291

Here's what MORTEC has to say about these castings:

3964291....69-72...rect..CLOSED..396, 402, 427, 454, 109cc chamber, Large or small hex spark plugs used, crate motor usage in years after 1970.

That head should really wake that 396 up in the top end but I think if you have any amount of Piston Dome you will have Detonation Problems on the Street running to days Pump Gas, with very little room to move the Dizzy. They would work great running a Moderate Domed 427 or Small Domed, perhaps Flat Tops, in a 454. Personally I find the Large Oval Port 049 or 781's more effective on the Street as it delivers better flow for Bottom End and Mid Range Power in Mid Displacement BBCs. If your ride is Strip Only under WOT all the time running Racing Fuel, by all means use the Rectangular Port.

I believe the LS6 used the SEMI-OPEN 118cc Chamber Head and these heads are more like L78 396/402 or L72/L88 427 material.

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This was my 70 1/2 Z28

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Last edited by Z15CAM; Feb 7th, 10 at 12:39 PM.
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post #3 of 9 (permalink) Old Feb 7th, 10, 02:34 PM
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Bryon
 
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Re: rect port head casting number 3964291

291 heads were used on the LS6 and L78 in 1970.

http://www.chevellestuff.com/qd/head...ng_by_year.htm

68 Camaro SS 396 - 468 BBC now, M21, 12 bolt 3.73 coded housing but w/ 3.31 gears.
Looking for 68 Camaro with body number NOR 181016
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post #4 of 9 (permalink) Old Feb 7th, 10, 02:57 PM Thread Starter
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dave
 
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Re: rect port head casting number 3964291

thanks for all input....maybe ill put a 468 together to use with those heads

80 z-28 with a big block....someday i will finish.[sigh] someday
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post #5 of 9 (permalink) Old Feb 7th, 10, 03:13 PM
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Dana
 
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Re: rect port head casting number 3964291

Dave,what is the intended usage of the engine?
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post #6 of 9 (permalink) Old Feb 7th, 10, 04:58 PM Thread Starter
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dave
 
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Re: rect port head casting number 3964291

Quote:
Originally Posted by RSCopo View Post
Dave,what is the intended usage of the engine?
the car is a 1980 z28
i have a nice 66 396 that runs [going to go through]
i have a 71 402 that needs rebuilding and i have a mark 6 454 that needs rebuilding
i want a roller valvetrain
i intend to drive the car and take to strip 3 or 4 times a year
i am going to have fiberglass front/deck-lid/bumper/nose[trying to lighten car].t-10 4 speed/3.73 gear,connected subframe.
im trying to run mid to high 11s with a 28 inch tall 9 inch wide tire
seems thats it although not the short version
thanks

80 z-28 with a big block....someday i will finish.[sigh] someday
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post #7 of 9 (permalink) Old Feb 7th, 10, 05:38 PM
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george
 
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Re: rect port head casting number 3964291

For the most part..oem rectangular heads belong on nothing under 500 cubes or a high winding 7 grand application and then with a dual pattern cam that favors that poor exhaust flow.
Even with a 468..I would still stick with an oval port.

George
68 Camaro
8-71 blown 461 Rat on E-85
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post #8 of 9 (permalink) Old Feb 8th, 10, 07:34 AM
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Bryon
 
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Re: Rect port head casting number 3964291

Dave,

You MIGHT want to rethink the T-10 idea if it is stock, unmodified. They don't take a lot of abuse - and sticky tires will make it worse. I had a BW Super T10 in a 1976 Trans Am. Engine was rebuilt to above stock specs and it lasted under abuse for a while. But one day I downshifted on the highway, coming up to a stop sign. Just a normal downshift. When I let out the clutch - it sounded like a hand grenade went off. It smoked the input shaft and cluster gear.

But back to the heads. Oval ports work fine on my 468.

68 Camaro SS 396 - 468 BBC now, M21, 12 bolt 3.73 coded housing but w/ 3.31 gears.
Looking for 68 Camaro with body number NOR 181016
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post #9 of 9 (permalink) Old Feb 8th, 10, 12:11 PM Thread Starter
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dave
 
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Re: Rect port head casting number 3964291

i have a doug nash 5 speed but its in a friends car, so im going to use the t-10till it breaks

80 z-28 with a big block....someday i will finish.[sigh] someday
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