Guest Perry Posted September 26, 2003 Share Posted September 26, 2003 I picked up a set of like new Vortec heads manufactured 5/99 at a swap meet last week. they came with a bunch of GM performance stuff and were hardly used at all and were supposed to be bone stock. I read up on the net a bit and supposedly they are good for up to .480 lift (some sources say .430) and you should leave about .020 to .030 inch of retainer to seal clearance. I pulled a couple valves and measured the retainer to stem clearance at .530 and on some valves more. my cam is a ZZ4 cam which is .510 exhaust lift and less (.474?) intake lift. Otherwise they don't seem to be cut on, looks like stock stem seals and the stem seal boss is the stock .560, appears to be stock springs at 1.440 diameter although a quick measure of the coil spacing shows they shouldn't go solid until over .650 lift. Are others finding the same thing? I think although .020 retainer to seal clearance is a little close they should be ok on a 5500 redline engine. also keep in mind there is another .170 of clearance to the guide so even a large amount of float should only touch/damage the seals not the head or retainer. My question is: does anyone know or would like to guess based on their experience with Vortecs if I got a set of heads already machined or if maybe they made more provision for lift at the factory as the years went by. and for those engine builders out there do I have enough clearance on that exhaust valve to run them this way? Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted September 27, 2003 Share Posted September 27, 2003 Check this thread out. I had my Vortecs machined after I got this info. Sounds like those heads have been machined already. http://www.hybridz.org/phpBB2/viewtopic.php?t=1880&highlight=vortec+heads Quote Link to comment Share on other sites More sharing options...
Guest Perry Posted September 29, 2003 Share Posted September 29, 2003 thanks much for the info. I recall my spring boss diameter at .840 so I may not be able to use the crane springs without some machining. I'm gonna take another look at it all and check out those springs on a tester at work to see if they appear to be stock or aftermarket. I have a set of screw in studs so I'll put those in or pin the stockers too before this thing goes together. Perry Quote Link to comment Share on other sites More sharing options...
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