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96' 5.7 Vortec cam qestions.

  
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96' 5.7 Vortec cam qestions.

 
breaker187_mike breaker187_mike
New User | Posts: 6 | Joined: 03/08
Posted: 01/28/09
05:50 PM

Alright, here we go.  I know already that there is only about 1 cam that i can put in my truck that will make it work right without a tune, i called Comp cams and that is what they told me.  Now, a question that has been boggling my mind.  If i decide to upgrade to bigger cam, what is it i have to drill out to give extra clearence.  I saw another post and they said that you could use a 3/8 bit to do this, but never said what it was.  They said that is all you have to do to vortec heads to add a bigger cam.  Now, if i do go bigger, the comp cams guy recommended a 08-502-8.  I was also thinking of maybe a ZZ4 but have seen mixed opinion on that one, some say you can, and some swear up and down it will not work with the 5.7 vortec.  What is the max lift on the cam i can go on a 5.7 vortec, that is if i drill out whatever needs to be drilled out.  If i do upgrade to a bigger cam i am going to buy the entire kit.  Timing gears, chain, lifters, rockers, and rods.  The cam is such a complex piece of the puzzle that i dont really know about and  need some help.  So after i get the cam decided on and know what to do with it, i would then get the tune to my pcm(if i get a tune, i no longer need a programmer, correct, cause that is a programmer in sence), my exhaust is going on next week, then new headers, and complete tune up with ACCEL plgs, wires, cap and rotor.  I already have cold air intake, and a throttle body spacer.  And for everyone out there wanting to know about spacers, i did notice a small increase in get up and go, so i know it did help alittle.  If some one could give me a complete run down on everything i talked about on here, it would greatley appreciated.  Long live the BOWTIE.  

Adam12 Adam12
New User | Posts: 9 | Joined: 01/09
Posted: 02/05/09
02:47 PM

Never heard about drilling anything out when putting in a bigger cam on a vortec motor, but you'll definitely need to get the matching valvesprings for the cam you choose.  if your motor is all original and a '96 model, your stock valvesprings are most likely tired and putting a bigger cam only makes this worse.  I would listen to the guys at comp, they offer tons of cams and know what works.  

chevman24 chevman24
Enthusiast | Posts: 430 | Joined: 08/08
Posted: 02/05/09
04:55 PM

Your stock engine should have a roller cam. So if your going with a roller cam you shouldnt have to replace the lifters, unless they are making noises. I'd replace the push-rods with a new cam and use roller rockers instead of the stamped ones(unless your on a tight budget), plus they will free up some hp. With timing gears you dont have to worry about chain stretch, plus with gears you get that staccato whine(blower sound). The negative with that is with an emissions engine yould have to go with the quiet gear drive set because it will mess with your knock sensor(s),which makes the sound less noticable.  

Adam12 Adam12
New User | Posts: 9 | Joined: 01/09
Posted: 02/05/09
11:03 PM

can't use a gear drive on that motor, it has a plastic timing cover, so there's nothing to hold the dogbone from walking back and forth...  

SMOKESHOW SMOKESHOW
Guru | Posts: 1001 | Joined: 09/08
Posted: 02/06/09
09:33 AM

The thing you are referring to on the head, is the valve guide.  The seat also must be modified.  The drilling you are referring to actually a tool that goes into a 3/8 drill and cuts the guide and the seat.
Accommodating more valve lift requires modifications to the valvespring seat and valve-guide areas of the head. The best route is to increase the spring-seat diameter from the standard 1.25 inches to 1.440 inches. Both Comp and Crane offer tools that use a valve-guide arbor to position the cutter. The Comp Cams cutter increases the spring-seat diameter while simultaneously reducing the outside diameter (od) of the guide boss. The Crane tool also cuts the valve-guide-seal diameter at the same time. Comp sells a separate tool that cuts a new guide seal and reduces the guide height to create additional retainer-to-seal clearance. Both cutters machine the top of the guide down to a 0.530-inch diameter, which is the standard size for positive-type aftermarket seals. This requires purchasing new valve-guide seals, since the factory uses a 0.560-inch guide to locate the seals. Another way to go is to have a machine shop cut the guide boss diameter to around 0.760 inch and reduce the seal height and use either the Crane H-11 tool steel spring (PN 99846) or the Comp spring (PN 981).

For more info check out the article, it is in CHP

http://www.chevyhiperformance.com/howto/97458/index.html