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  #16 (permalink)  
Old 09-20-2009, 10:10 AM
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The original vortec heads were cast in Canada with an intake port in the 180cc runner volume neighborhood. Then GM moved the foundry to Mexico when it did they reduced the runner volume to the 165 to 170cc range. Around here people ask Canadian or hecho en Mexico heads. With a radiused valve job bowl blend and some short turn work the mexican head preform almost as well as the Canadian heads. Take your heads to a race shop with precision valve seat cutting equipment that will equalize seat height which equalizes spring height and gets chamber volumes closer.don't go to the parts store where they still use grinding stones.
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  #17 (permalink)  
Old 10-31-2009, 08:13 PM
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You need to tell us the casting numbers. 305 engines don't use the "Vortec" head, they use the standard 305 head but GM called it a Vortec but it does not have the chamber and port features of the L31 heads.

casting number for the L30 305 vortec

12552520

12558059...97......305..........Vortec, truck, 1.84"/1.5" valves


and they have the same port but smaller intake valves smaller combustion chamber 58 cc use the same intake and they made 230hp whit a very small cam
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Old 11-01-2009, 01:01 PM
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Originally Posted by oldbogie
The 3 angle valve job is shop standard. It is usually a 45 degree seat with a 30 degree top cut and a 60 degree cut in the throat. The top and bottom cuts position the seat and valve, determine the width of the seat and provide a smoothing transition for the flow as it approaches and departs the seat. Generally the maximum the flow can turn 15 degrees without separation from the wall so a three angle is the minimum you can get away with unless performance is penalized. Performance valve jobs often take this to 5 cuts, but for a street engine the cost isn't justified. Keep in mind that cutting seats sinks the valve, this makes the combustion chamber bigger in volume which reduces compression and makes the valve stem appear longer to the valve spring reducing its pressure. While the spring can be shimmed to recover the pressure, there's nothing to be done for compression short of changing pistons and or valves to refill the additional space with something. You can go to new valves, especially larger valves, that require the seat to be moved into fresh material for a complete recovery. The guides need to be inspected for stem clearance and corrected if necessary, this needs to be done before doing the seats. You need to talk with your local shop, this stuff gets expensive pretty quickly, which is why new Vortecs are so popular since you can drive the cost of rebuilding heads well into the cost of new ones without much effort.

Bogie
you can have new seats installed and the depth corrected to spec
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Old 04-23-2012, 09:09 AM
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i have got 4 vortec heads from wreckers all 062 castings .... ALL CRACKED ! so i asked around and found out that they are notorious for cracking. i looked into it a bit more and found out you can get 060 castings . just wondering if they solved this problem in them?
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Old 04-23-2012, 10:26 AM
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060 its the part number for the 062 head

350 vortec head there only 2 number 062 and 906
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Old 04-23-2012, 10:38 AM
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Quote:
Originally Posted by i heart square bodys
i have got 4 vortec heads from wreckers all 062 castings .... ALL CRACKED ! so i asked around and found out that they are notorious for cracking. i looked into it a bit more and found out you can get 060 castings . just wondering if they solved this problem in them?
There are no "060" casting number Vortec heads. There is a part number 12558060 Vortec cylinder head assembly sold by GMPP that is made from the casting number 12529093 head.

The info above about the L30 5.0L c/n 059 Vortec heads having the "same but smaller" ports is incorrect. The 059 head has a swirl vane cast into the port. Smaller than the vane in the TBI SP heads, but it's there none the less.

A Crankshaft Coalition wiki page on the L31 5.7L Vortec head is here. BTW- anyone wanting to edit/add info to this, or ANY CC wiki page, please feel free to do so.

Last edited by cobalt327; 04-23-2012 at 10:48 AM.
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Old 04-23-2012, 03:46 PM
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I haven't worked on a set of vortecs in a while but I believe they come standard with a 3 angle valve job, its not the best but if you're tight on pennies id just clean them up, smooth up the bowl tap for screw in studs and reassemble. Id also work on the valves or replace them.
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Old 04-23-2012, 04:52 PM
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Hardened exhaust insert seat 906 heads are reported to come w/a single angle on the exhaust, all others are three angle from the factory.

The valves are back cut from the factory and are fine to use unless the tips are ground too far to clean them up or the margins are too thin after cutting. If they're replaced the new valves should be back cut same as the factory valves.
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