04SilveradoMykk

Hello Everyone,

I've decided to retire my current set of worked over OE 906 Vortec heads. After the umpteenth time of re-adjusting my rockers and setting valve lash, not but just minutes after the fire up the valve train sounds like a diesel again! My assumption, something happened during the pinning of the press in rocker studs to weaken them or the COMP 26918 beehive springs with 774 retainers has created too much spring pressure and has wiped out the GM roller lifters. Either way, parts are going to need to get replaced.

I recently sold a few misc parts I had laying around my garage, via EBay. And in a short period of time aquired enough $$ in my paypal account to purchase a new set of heads. I found this pair of Vortecs from a company called J&C enterprises, and what had me sold was the fact they were new. (And the 2.02" / 1.6" valves didn't hurt either)

http://cgi.ebay.com/ebaymotors/ws/eB...3617&viewitem=

Fast forward a week, the UPS delivery arrives and I unbox my new pair of Vortec heads.





However, I couldn't find any kind of info about this casting #



After doing a bit more research on these heads, I discovered they are made by Patriot. I know alot of guys swear Patriot is junk (and I have seen the pictures too), but I've inspected these heads closely (without a tear down) and have seen nothing but nice clean machining and clean castings. I was curious as to what the advertised flow numbers were and how they compared to other Vortec SBC heads on the market. Here is what I found...

Stock Vortec 906: (according to chevymania.com)

Intake / exhaust
.100" 70 48
.200" 139 101
.300" 190 121
.400" 227 140
.500" 239 147
.600" 229 151

Patriot 2.02" / 1.6" - 185cc intake / 60cc exhaust (from patriots website)

(@ 28" water)
Intake / exhaust
.100" 74 50
.200" 140 99
.300" 202 145
.400" 235 175
.500" 241 183
.600" 246 190

Edelbrock E-tec 60979, 1.94"/1.5" - 170cc intake / 70cc exhaust (from edelbrocks website)

Intake / exhaust
.100" 64 54
.200" 122 96
.300" 177 124
.400" 217 147
.500" 229 166
.600" 232 175

Edelbrock E-Tec 60689, 2.02"/1.6" - 200cc intake / 80cc exhaust (from edelbrocks website)
intake/exhaust

.100" 67 57
.200" 122 110
.300" 175 153
.400" 223 182
.500" 252 196
.600" 259 204

Those are some pretty competitive numbers by patriot. Especially for the price, all they need is a little bit of exhaust port work and they could provide some very stiff competition to the more expensive big boys

Ok, so the heads are adressed. What about the valvetrain?

Everytime I've had the valve covers off my SBC I thuroughly inspect my Proform 1.6 ratio aluminum roller rockers for any wear/damage/problems, just from reading the horror stories. But I can not find anything wrong with them. So I will re-use my Proforms, Since the lifters are suspect of a problem I decided to replace them all with a set of COMP 875-16 roller lifters that will work with the OE lifter retainers & cage.

Since the intake manifold & heads will be off and the cooling system drained anyway I figured I'd take advantage of the oppurtunity and go one step further. I decided I was going to replace my LT4 hotcam with a bumpstick that would offer a bit more duration and since fuel injection is no longer a concern perhaps a tighter lobe seperation too. That and something I can take advantage of my 3200 stall converter, long tube headers & 4:10 gears. The cam I found that would meet my needs, the COMP XR276HR-10 coupled with my 1.6 rockers.

.535"Int/.544"Exh
224/230
110

And from what I can see, the Patriot vortec heads are a good combo for this cam too. They can accomodate a max lift .575" and COMP recomends their 986 or 987 springs with this cam @ 322 & 344lbs/in, while the patriots come with closed pressure 115 lbs. @ 1.800" open pressure 310 lbs. @ 1.225" (.575" lift)... thats a pretty good match.

Right now, my SBC is:
4.040" bore x 3.48" stroke
4.1 x .039" head gasket
flat top pistons, four valve relief -5cc
.004" from deck

equals 10.34-1 compression. While I need to replace it anyways, I decided I would use a Mr.Gasket 1134 head gasket 4.13"x.028" to bump my compression up to 10.6-1 (probably a 10.5-1 with compression loss through the cam) wich would still be a 91 octane pump friendly street driver.

What's the estimated power output after all the new goodies?

Desktop Dyno puts the combo @ 449HP @ 6000 / 445TQ @ 4500.. and an amazing 406TQ @ 2500



Cheers ~Mykk

04SilveradoMykk

Got started, a couple hours worth of work.





LT4 Hotcam is out. There is an obvious wear pattern on the cam from the rollers... but the lobes are not getting worn down at all. I'll put a mic on it and see if it's in spec before throwing it up on EBay.



The green oil is due to the UV die I had in there to help locate a leak.

The COMP XR276HR-10 cam is lathered in black moly and stabbed in place.



later eve I'll (with a ton of help from a friend) finish her up, transfer the valve springs over to the new heads with the new retainers and get her back together for the drive home.

Cheers ~Mykk

04SilveradoMykk

Didn't get as far as I would have liked, I stopped at about 1:30a while I was still thinking clear before I started making mistakes.

Heads assembled & torqued down with 26918 springs & 787 retainers.



valvetrain is adjusted per comps instructions using their 875 lifters



Those spectre "fabbed" aluminum valve covers do look pretty mean





...here is to show the difference between the Comp 787 vs 774 retainers on the 26918 when installed on gen IE vortec heads

787 on the left.....774 on the right





The comp 26918 springs, 787 retainers & proform 1.6 ratio aluminum roller rockers

SlvrSierra4.8

iTrader: (24)

Looking forward to your feedback on the upgrades. I have an almost identical setup as your previous vortec headed configuration sitting on an engine stand for my Nova project

04SilveradoMykk

A little vid:

http://www.youtube.com/watch?v=D7vtulnfwPU

GMCtrk

iTrader: (27)

cool video mykk. Sounds GREAT.

Cooder5.3

Sounds wicked! Gotta love the old school muscle sound of the flowmaster.

53bowtie

iTrader: (6)

Curious why you went with a carb setup Mike?? Sounds awesome! Looks like it is going to have lots of usable torque too.

southern_chevy

iTrader: (9)

Got to love the torque of the sbc motors. Sound like it will be a good combo. Truck sounds and looks good as well.

budhayes3

iTrader: (19)

Sounds awesome Mike, seems like you really have it nailed down now I grew up on carbureted sbc's so I've been very interested in your build. It would have been kinda neat if you could have gotten the EFI bugs worked out, but there's something really cool about the old school carb setup in a new school truck