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i am up grading my 305 HO. 350 vortec heads, new intake,sum 1103 cam, gear drive, headers. keep my electric qjet, hei,smog equip[not operating-must be there for NC inspect] how much shud i mill the vortecs and what head gasket? any help appreciated. Jerry mgysgt usmc ret:salute:
 

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First off, thanks for your service to our country. To answer you question, it really depends on what you want to get out of the engine. I think the Vortec heads are a good choice. But as far as milling the heads and choice of head gaskets, it will depend on what compression ratio you want to achieve. Here is a good calculator to help you figure out what you have and how to get what you want:

http://www.csgnetwork.com/compcalc.html

What pistons do you have (flat-top, dished)? For comparison, what is the combustion chamber size of your present heads? Are you going to deck the block? You should take quench distance (distance between the top of the piston and surface of the head) into consideration when selecting head gaskets and final compression ratio. Optimal quench distance is about .040". Pistons at TDC are usually about .030" below the block deck from the factory. A thinner gasket will give a better quench distance and raise your compression.

Remember, milling the heads changes the mating angle at the intake manifold. If you go too far you'll have to have the manifold angle milled to match.

I hope this is helpful.
 

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heads

Be sure to check for interfearence on the valves at the mating surface. If memory serves, they have to be unshrouded there due to valve size & the 305 bore size. Not a big deal, but make sure they pass by the cylinder.

You have down a new intake. Remember that Vortec heads have verticle mounting bolts instead of the traditional mounting system.

Jim
 

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Discussion Starter #4
305 with vortecheads

my engine is stock l69 in 85 monte. combustion chambers are 58cc. vortec is 64. dont have heads off yet. want to keep cr above 9-1. i just want a street engine with a little more oomph. will be running 2004r and 3.73 posi. tks Jerry
 

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You should try to find vortec heads that came off a 305. To go from 58cc to 64cc, you are giving up a good amount of compression, in my opinion. Not to mention, you really might have some issues with the combustion chamber. Or, maybe find a good 350 to swap in...
 

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Discussion Starter #7
305 with vortec heads

thanks to all ofyou for your comments. still no ideas about milling the heads? Jerry semper fi
 

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You should try to find vortec heads that came off a 305. To go from 58cc to 64cc, you are giving up a good amount of compression, in my opinion. Not to mention, you really might have some issues with the combustion chamber. Or, maybe find a good 350 to swap in...
X2 ^ The 305 Vortec heads have the 58cc chambers. If you can find a set of those you'd be better off. As for milling the heads, I try to avoid shaving any more than necessary because of angle changes that affect intake gasket sealing. But I'm not a professional engine builder, that's just my personal preference.
 
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