Intake Manifold SBC 350

I'm looking at purchasing a new intake manifold for my 350 SBC thats in a 3rd gen camaro. The engine was transplanted from a 71 chevy pick-up. I know a dual plane is a must and thats what im going to go with.
My question is about the edelbrock air gap manifolds. Ive heard they can make more power and thats always a bonus. The problem is that the air gap intakes dont have the exhaust crossover.What is the intent of the exhaust crossover? Will blocking it off hurt anything? Will starting the vehicle in harsh winter be an issue without the crossover?

I appreciate any assistance
Mike  

It is mainly to help heat the fuel in cold situations to make the car cleaner for smog fun.  Do you have to smog the car?  

No smog here. knock on wood!! If its not going to hurt anything then i dont see a problem with using that intake. I've had a single plain intake on it and a dual plane, i can feel the difference. The dual being the better one. Both intakes i mentioned have the crossover thats why i'm wondering why the air gap doesnt.  

You will be sacrificing a small amount of cold weather warm up time.  Once the engine is warm you will be fine.  Most intake gasket kits come with small tabs to block off exhaust cross over.  

It will affect the cold start up. It will probably keep the choke on longer and make the vehicle harder to keep running when cold.

If this car is driven A LOT in cold weather I would get the non air-gap variety - the power increase isn't all that large and I doubt that outright power is of all that much importance.  

Technically, it wont be driven A LOT,as GibTG stated. Mainly to work and back which is only a mile away. Perhaps around town on errands and such.  
Its ordered and already has been shipped,damn!!! The car is already hard to start, but thats bc i have a single plane intake on it. Which is bc the bolt holes for the carb studs on my performer rpm are cross threaded to the point there arent any threads left. This is probobly a dumb question but would the dual plane air gap be better than the single plane? I dont want to pay to ship it back, course i could refuse it.  

Get an electric choke for the carb or better yet, go with a manual cable style. Why is it hard to start, is the choke not closing all the way when it's cold? Either manifold you use will not cover up a malfunctioning choke. The Air-Gap is a good manifold and I wouldn't hesitate to use it. As for your single plenum, get a 5/16 Heli-coil kit, fix it and sell it to clown down the road who thinks it's the hot tip for the street.  

It has an electric choke. The demon manual says that the way they are designed it's not supposed to close all the way. I also think that the jets were too big so the engine was running rich. So the oil was thinned out by the rich fuel mixture. The single plane manifolds carb studs mounting holes are fine, its my performer rpm dual plane that i stripped out the bolt holes on.  

Engines running on gasoline are harder to start when they are lean, not rich.

If there is enough fuel getting into your oil to thin it out you have something mechanically seriously wrong - like rings acting like they aren't even there.

So, you had a Performer RPM and you bought a brand new air gap version? I surely would've fixed your old manifold first, they are virtually identical!  

I'll just refuse the order. I havent received it yet.So by not having enough fuel sent to the cylinders they wont run properly and the fuel wont combust and will end up in the oil?
It was running fine before it got really cold here.
When the engine was in my truck i had size 53 jets in it and it ran perfectly and the plugs were a golden brown. If it didnt run like it did i wouldnt have done the swap.

Changed the jets to 80's and the problem went away. the engine starts alot easier and drives better. I just hope i didnt ruin the rings. It still has good power, just at idle it runs rough.  

What size drill bit would i use with the 5/16 heli coil?  

It says on the package. Usually 3 sizes below the bolt size, and you need the Heli- Coil tap as well.  

I went to a hardware store and they wanted 70 bucks for the kit. Thats just for 5/16 thread. Damn thats too expensive to fix one bolt. they should sell the heli-coil taps seperately. Found one online for 20 bucks through amazon.