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Author Topic:   vortech heads or GM 492?
Crazzy 4 Racin
Dirt Roller

Total posts: 10
posted May 16, 2000 02:30 AM
i was wonder which heads you thought would be better. i read a article in stock car racing mag saying that the GM 492 casting flowed very well out of the box. i have heard that vortec head are a good head also. which would you recomend.

thanks,
crazzy

[This message has been edited by Crazzy 4 Racin (edited 05-16-2000).]

[This message has been edited by Crazzy 4 Racin (edited 05-16-2000).]

Crazzy 4 Racin
Dirt Roller

Total posts: 10
posted May 16, 2000 03:00 AM
just a little info on the heads.
the cylinder head ( casting p/n 3991492 ) was originally installed on special high-performance small blocks such as the 302ci z-28 and the 350ci LT-1. it is populary known as the "fuel injection" head because it shares many features with the previous high-performance heads. this head has straight spark plugs, 3/8" screw-in studs, pushrod guideplates, and heat riser passages. the 64cc combustion chambers are machined for 2.02" intake valves and 1.60" exhausts.

the cast iron vortec cylinder head was first used on the 1996 pick-up truck . the intake and exhaust ports are very similar to the corvette 350 LT-1 heads. this head includes 1.94" intake valves and 1.50" exhaust valves, with pressed-in 3/8" studes. this head with compatible valves flows more air than bow tie head ( p/n 10134392 )but the casting may not be as durable. the water passages are the same as the original 1955 small block design

[This message has been edited by Crazzy 4 Racin (edited 05-16-2000).]

jammin
Dirt Administrator

Total posts: 3279
posted May 16, 2000 07:41 AM UIN: 16262997
Are these 492's raised rail heads like the Vortecs?

4b316
Dirt Full Roller

Total posts: 39
posted May 16, 2000 08:59 PM
Vortec heads will outflow bow tie heads rite out of the box

Crazzy 4 Racin
Dirt Roller

Total posts: 10
posted May 16, 2000 10:52 PM
i,m not sure if the 492's have a raised rail or not. the article didn't specify. the article was on a street stock build up and these heads were the supposed to flow really well out of the box. and if you angle mill them and seal the coolant holes for the spark plugs they are even better.

vortec
unregistered Total posts: 10
posted June 07, 2000 01:37 PM
Vortec heads (stock) will out-fllow all heads with the same intake runner volume of 170cc and many heads up to 200cc (Holley Systemax, Brodix 8) at .400" lift. They also have a better chamber design and test out at 62cc in size. If your going to race them, there are some modifications to perform.

[This message has been edited by vortec (edited 06-07-2000).]

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