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Author Topic:   GM Heads question
No Shame
Member
posted December 10, 2001 12:34 AM
Yes the Vortec heads are great !! By going to a 2.02/1.60 valve combination , your air flow increases dramatically ! On my flow bench , by going to the 2.02/1.60 and blending the pocket area , you pick up almost 100hp(potential) worth of air !! But don't go to a 2.055" intake , unless you are willing to un-shroud the chamber and gain some CC's . As far as angle milling , we generally roll these heads over .080" , and then take an additional .015" off after they clean up . Then we re-correct the intake and exhaust faces , and spot face the head bolt holes . I've seen these heads milled much farther by other engine builders , but they usually have a big problem with head gaskets ! The deck on the Vortec head is very thin , so you are limited to how much you can mill them , and still retain enough thickness to hold a head gasket . As far as over all compression ratio , you can cut the 461's much farther . But in my opinion , the large difference in air flow that you get with the Vortec's , well out weighs the 1/2 point loss in compression ratio ! Hope this helps !!

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


hughes
Member
posted December 10, 2001 10:06 AM
Hey sdhnc29, when racing with the Vortec heads in the classes where you can't port/ polish, is cleaning up the bowls/ casting lines worth the time. I also heard that you can cut the idle ridges out for around 20 H.P. I was also considering opening up the exhaust. But on the other hand you hear that with Vortec heads you can only ***** them up. What kind of work do you think would be good for Vortecs in the classes that aren't wide open on the Porting. I've alot of good/ knowledgeable replies from you and would like an opinion from you.


sdhnc29
Member
posted December 10, 2001 09:43 PM
Hey hughes , thanks for the compliment !

Yes , going to 2.02"/1.60 valves and blending the bowl area is definitely worth your time !! As I said in my previous post , there is about 100hp worth of air flow in the larger valves and opening the bowls up . As for the intake and exhaust ports , there is only very little that can be improved on . GM actually did there home work when they designed this head !!!

In a class where you are limited to absolutely no port work /polishing/ or bowl jobs , then you can still go to the larger valve and gain ! Though the gains are not nearly as great , it would still be worth going to the larger valve . Usually in classes like this , rules are written in a way that you can do whatever you want with the valve job , just no port work . If this is the case , then I'd suggest finding a machine shop with a NEWEN (CNC) seat and guide machine . With this machine (the same one I use) , you can go into the pocket area with several different cut's , and achieve a pocket that is almost as good as a hand blended pocket !! The only area that actually suffers a little in the bowl , is the short side radius . But you can still gain a ton of air over the stock 1.94/1.5 valve's if you do this ! This should be done to both the intake and exhaust pockets !

As for the exhaust ports , they seam to be very good as cast . If your rules allow porting , then you will want to do most of your work around the guide area .

If there is anything that I've missed , just PM me , and I'll be happy to go into further detail , and answer your questions .


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