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Old 11-15-2002, 01:15 PM
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Post ARE 305 and 350 VORTEC HEADS SAME

Are the vortec 305 and 350 heads the same. I have had some tell me that the heads are the same and some say they are different. I have a vortec 305 and I was wanting to put a 350 block in, but some say the 305 heads are the same they will work on the 350 block without changing my compression and others say they are differnt and it will change. Please help.

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Old 11-15-2002, 01:50 PM
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Guess what, I didn't know that a Vortec head was available on a 305. But why don't you find the part number for your vortec heads and check them against the ones sold by Scoggins Dickey. I do know that the favored ones have small 64cc combustion chamber volumes and 170cc intake runners so it may be possible that they are the same.
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Old 11-15-2002, 01:56 PM
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I don't think so. The 350 casting numbers end in 906 for one set and 062 for the other.
You still can't tell without looking at both heads to compare. I have seen some old 193 castings (not vortec) with smaller chambers and 1.84 intake valves and the same casting number with bigger chambers and 1.94 valves. I would suspect the same goes for vortec heads. Vortec 305 probably have smaller chambers and 1.84 intake valves. Not really a big difference if you want to put bigger valves in and increase compression.
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Old 11-15-2002, 02:09 PM
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The 305 vortec heads have a slightly smaller combustion chamber & the 1.84 intake valves. I have been told that they can be easily converted to the larger 1.94 intake valves, but have never tried this myself. I use vortec's on both street & race motors with pretty good results. Phil
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Old 11-15-2002, 02:18 PM
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The 305 Vortecs have smaller runners, smaller chambers, and smaller valves, They would still work nicely, but wouldn`t give the full potential of the 350 Vortec head. this is what it says in Chevrolet High Performance.
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Old 03-31-2011, 09:49 PM
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Sorry to revive this, but that means that I can fit 350 Vortec 906 heads on my 305, and not have compression problems? I have the 64cc 350 906 heads with 0cc of dish with a 4.100" diameter, .015" thick head gasket running at 9.72:1CR, and I have the same thing with a .021" head gasket running at 9.56:1CR, is that right?
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Old 03-31-2011, 10:42 PM
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Quote:
Originally Posted by 90CamaroRS
Sorry to revive this, but that means that I can fit 350 Vortec 906 heads on my 305, and not have compression problems? I have the 64cc 350 906 heads with 0cc of dish with a 4.100" diameter, .015" thick head gasket running at 9.72:1CR, and I have the same thing with a .021" head gasket running at 9.56:1CR, is that right?
That's about right for a standard bore engine w/the piston 0.025" in the hole.

How are you getting a "0" volume piston? All the pistons I'm aware of have valve reliefs.
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Old 03-31-2011, 10:59 PM
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Yeah but aren't they only 2cc? I'm thinking 4cc at the most
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Old 03-31-2011, 11:38 PM
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Quote:
Originally Posted by 90CamaroRS
Yeah but aren't they only 2cc? I'm thinking 4cc at the most
5 to 7 if they're eyebrows, more if they are a trough style.
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Old 04-01-2011, 09:01 AM
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How can I tell?
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Old 04-01-2011, 09:14 AM
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Quote:
Originally Posted by badriand
Are the vortec 305 and 350 heads the same. I have had some tell me that the heads are the same and some say they are different. I have a vortec 305 and I was wanting to put a 350 block in, but some say the 305 heads are the same they will work on the 350 block without changing my compression and others say they are differnt and it will change. Please help.
Different, basically the L31, 350 Vortec head is a new design with different ports and chambers. The LO3, 305 is the same old 305 head with a new name.

Bogie
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Old 04-01-2011, 05:13 PM
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Quote:
Originally Posted by 90CamaroRS
How can I tell?
Remove a spark plug, run the piston to TDC, shine a strong light into the hole, stand on your head and look through the hole.
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Old 04-01-2011, 05:36 PM
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Quote:
Originally Posted by 90CamaroRS
How can I tell?
Find a borescope and look .
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Old 04-01-2011, 05:38 PM
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For anyone wanting to see and possibly read up a little on the differences between the 305 and 350 Vortec heads, take a look HERE, post #478.

Basically, the 305 Vortec chamber is much like the preceeding 305 head chamber. The big difference is in the ports. The Vortec 305 heads have a vane in then similar to, but smaller than swirl port heads. They have been successfully used on smaller displacement engines like the SBC 283/307/305.

From a previous post:

Quote:
They have a "standard" (not heart shaped) 58cc nominal chamber, 1.84" x 1.50" valves. The intake port is 165cc, the exhaust port is 58cc. If the chamber shape was the same as the L31 head they'd be a no-brainer for a small displacement SBC, IMHO.


l30 305 VORTEC CHAMBER

They also have a swirl port-type ramp (likely why the intake volume is slightly less than the L31 head), although the ramp isn't nearly as pronounced as swirl port TBI heads like the 14102193, etc..


L30 305 VORTEC INTAKE PORT RAMP

Photos credited to "Twistedwrench", from a THREAD that also has some info on them.

TBI SWIRL PORT RAMP

Last edited by cobalt327; 04-01-2011 at 06:07 PM.
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Old 04-01-2011, 06:01 PM
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Swirl port heads.
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