Will Clark

Ok, So I just got all my stuff in from comp cams and GM. I have only 1 problem at the moment, I need to know if the GM Vortech heads can have the spring seats machined to 1.50 inches without springing a leak.

So has anyone fucked up a set doing this or had any success with them?

Know anyone that might of been there and done that?

FASTONE

Will, I'm pretty sure you can ,usually they cut the top of valve guide for the new seals and spring seats with the same cutter.If I were you I would find a machineshop that has experience with the Vortec head,they should be able to answer your questions.I don't think you'll have a problem cutting the spring pockets!! BTW I love my VORTEC heads, they are heavily ported with bigger valves on my 408 and they make plenty of POWER!!

Steve - Race Eng

iTrader: (1)

I'm working on a set of Vortec heads casting #12558062. I have already cut the spring seats to 1.500". No problem. I would not cut any deeper however.

Steve Demirjian
Race Engine Development

Will Clark

All right, cool. My machinist is experienced and is really good at what he does, but he hasn't done a set of Vortec heads before. He also mentioned that depth isn't what he would shoot for Just the aftermarket look-a-likes. I'll be sure to check the casting number before I buy anything.

Well I already got the springs, retainers, seals, and locks from Comp Cams. I figure the best deal would be to buy the fully assembed heads from GM (its only like $12 more per head) and use the same valves. Then get those pressed in studs out of there and tap in some ARP studs.

Will Clark

Anyone have any idea what the max cut is on the 906 casting? Whats the difference between the 062 and the 906?

FASTONE

I don't know what the difference is but I know the 062 are the good heads for 5.7 I know they make a 5.0 head that not desirable,smaller valves and ports!

Will Clark

I believe the 906 is much more common.

FASTONE

The 906 may be the new number that replaced the 062, as I said I don:t know.I"m sure those heads are good since you bought the as a hp head !Will are you going to do any port work on those heads?The Vortec really responds to some good porting,mine flowed 252 at .400 on intake and 203 on ex. at .500 lift thats with about 180 cc port and bigger valves, the bigger valves didn't help that much! MY 81 Camaro 4 speed ran a 7.59 at 89.91 (1/8) on street radials with a 1.93 60 ft time,first pass I spun all the way down the 1/8 mile track!Which cam did you get, and is it a roller? P.S. the 062 was the 1996 to 1999 350 cu. in. truck head.

Cstraub

iTrader: (1)

The 906 is the preferred casting for the 2 barrel stuff that I cam. The heads respond very well to porting. No problem on 1.50" machining but do not go more then .015" deeper then OEM spring pad.

Chris

Will Clark

I do plan on porting the heads and polishing the exhaust valve.

I picked up a hydraulic roller cam from comp, .510/.520, 110 degree lobe sep., 288/294 duration seat to seat.

Thanks for the info, its really valuable to me.

Will Clark

Sweet! How sure are you of this, I mean, how do you know this holds true?

The last thing I wanna do is screw up a $230 chunk of metal

FASTONE

Hey Will, you are welcome glad to help,be sure to get your machinist to check retainer to seal clearance I think about .470 is all there is,but if you "re cutting bigger springpockets you"ll get the seal clearance fixed.Also make the pushrod holes bigger as you can have problems with1.6 rockers(you can do this with a drill or rattail file, or grinding bur).When I ported my heads I squared up the intake where it slants in and opened up the pinched area by pushrod When you do your pocket work on intake sa 1/2 below seat don"t take out much metal there as it will hurt your flow just smooth and blend in,streamline the guide, widen the space between guide and port wall,on the ex. side go up and out on both sides just smooth short side radius don"t go down!!I got mine to flow 205cfm!be sure to match your intake too.GOOD LUCK !!

Cstraub

iTrader: (1)

Will,
Numberous track championships in 2 barrel racing from Maine to Florida and out to California. One of our stoutest pieces was dyno'ed at Heads By Rick when he was still in florida, that 2 barrel was around 468HP and 480#/ft with a flat tappet and 12 to 1. Best season it won 16 out of 17 races. HVH prefers the 906's as they make the most power. Also Pro/Topline, now OOB, based their Vortec off the 906 when they made an aftermarket head.

Chris

Will Clark

Yeah, my machinest is cutting down the guide boss and all that. I'm gonna get him to drill/thread ARP studs as well.

Will Clark

Cool, then I'm going to go order a set of heads now.

FASTONE

I wonder what the difference is on 906 and 062?Since Chevy guit making the V8 VORTEC IN 1999 SO WHY A NEW DESIGN?The 062 has the same intake port as LT-1 head ,also the Top Pro-line heads don"t flow as good as the 062 Vortec head !Cstaub, I"m not disagreeing with you just have"nt heard much about the #906 maybe it is improved over the 062.Anyway they don"t compare with the LS-1 heads for sure!