396 intakes - Team Camaro Tech
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post #1 of 11 (permalink) Old Oct 10th, 05, 04:34 PM Thread Starter
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396 intakes

Hi, I have a 1967 rectangle port intake manifold # 069 can I use it safely on Oval Port Heads ? If so do I need a special gasket ? THANKS
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post #2 of 11 (permalink) Old Oct 10th, 05, 05:01 PM
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Re: 396 intakes

No you would have a gross mismatch in port size.

Now that being said yes poeple have done it just to prove they could.
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post #3 of 11 (permalink) Old Oct 10th, 05, 06:45 PM Thread Starter
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Re: 396 intakes

Thanks, would I create any problems with the engine ( like a huge vacuum leak) or would it cause engine damage ( coolant leak) or what. The problem is I can't find any REASONABLY priced Rect. port heads and I already have the intake. Also I want to keep compression at or around 10:1 with a mild cam and a th400 trans with a 2K stall converter and a 3.42 gear. I want the car to "go good" but still be drivable around 350-400 HP any suggestions. Oh yeah I want to use a stock intake GM with a holley. THANK YOU !!!
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post #4 of 11 (permalink) Old Oct 10th, 05, 07:43 PM
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Re: 396 intakes

Use big port gaskets. I know it should run terrible but every one I have come across ran better than with an oval manifold.
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post #5 of 11 (permalink) Old Oct 10th, 05, 10:09 PM
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Re: 396 intakes

You can find a cast iron O-port intake at a bone yard or e-bay for $25-50. What heads (casting number) do you have? There are two sizes of O-port heads,..large and peanut. Let me know and I can give a half dozen intake casting numbers that will work much, much better than what you're suggesting. Or you may find a good used aluminum intake,..what carb are your running? Q-Jet or Holley?

Also,..don't mess with the rectangular stuff,..it was too much for a 396 in the late 60's and it still is.
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post #6 of 11 (permalink) Old Oct 11th, 05, 05:46 PM
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Re: 396 intakes

It works fine. I have seen many people do it. Going from oval head to square intake. Who cares. I would probably sell it and buy a old Edelbrock C396 and slap on it. The ports will match and you will get the the same or better power. Why play Frankenstein? If you don't have the cash, I am sure someone will buy or swap you out for the 069. I assume you want it to look like an L78?
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post #7 of 11 (permalink) Old Oct 11th, 05, 07:03 PM
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Talking Re: 396 intakes

Camarojamie don't take this the wrong way. For your build up you don't need rectangular port heads, in fact it'll hurt you more than help you. The oval port heads will flow just fine for your build up and keep the incoming fuel charge atomized better. The rectangular ports are just too large, even for most of the motors they came on. You'll make more power with the ovals where you can use it and need it. I've run the ovals on 450-500 hp 396 motors and they work very well. I lot of guys get caught up in the romance of the bigger part is better. Your 10.5:1 396 will love the oval heads, especially with your cam and smaller rear gears, you'll be happy.

Chevy made an oval port high rise cast iron intake for use with a Holley carb in 65-66 I believe. This intake works great on the oval heads for a build up like you are considering. Plus it's a high rise and the Holley mates to it. It's the only oval port intake for a Holley that Chevy cast. I can't remember the numbers on it, but some of the others on the board do.
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post #8 of 11 (permalink) Old Oct 25th, 05, 09:58 PM
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Re: 396 intakes

I believe the number for the bb cast iron o-port holley manifold is 3866948.
also... if you cant track down that manifold and you're after a stock look, holley makes spreadbore carbs that will match to the plentiful Q-jet manifolds.
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post #9 of 11 (permalink) Old Oct 26th, 05, 03:33 AM
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Re: 396 intakes

I would be glad to trade you a 67 dated 948 for your 069?
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post #10 of 11 (permalink) Old Oct 26th, 05, 04:00 PM
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Re: 396 intakes

Wow, I have been asking the very same question. I have a 163 that I plan on trying on a 427 with 290 oval port heads. Have talked to lots of folks who say this works fine, just have to use rect. port gaskets.Glad to see the subject discussed.


02 Berger 380hp 6spd red/white conv/Lots of L78 Novas.....69 SS350 Camaro..Karen's new addition!
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post #11 of 11 (permalink) Old Oct 26th, 05, 05:50 PM
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Re: 396 intakes

I actually have a friend who ran a engine just this way but he took the heads and made the intake runners like funnels using a rect port gasket he rounded the edges to almost apear to be rect but he didnt go far at all into the head maybe a 1/2 inch. The car was a Center steer Altered so it didnt weigh much but it did run 5.50s all day long at 120s mph. Im not saying this is what to do but it a case I know of that seemed to work.
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