Blackstone Heads

Stefs oil pan  383, page 2  Final assembly

Mike is on his third pass at these heads, the LT1 castings that came on the car when I bought it new in '96.  The first go 'round, back in the summer of '97, was fairly mild because the car was still in a mild state of tune and was driven 60 miles daily in California rush hour traffic.  Then, in late fall of '98, a blown head gasket enabled another trip to Mike's shop for "fluffing", as he put it.  The car was in the 11's now, so I asked Mike to open things up a bit.

Fast forward to fall of '99 and Boom #3; bent valves, worn guides, warped decks, and the new shaft rockers pushing the lift higher than the previous Isky springs could handle.  Mike didn't suggest additional porting, but I wanted to make sure the bigger 383 was well fed.  And well exhausted!  All my 1/4 mile times are through a full, exit-at-the-back-bumper exhaust, including functional catalytic converters, so I insisted that the exhaust ports be as high-flow as he was comfortable with.

Because he is a pro head porter with decades of experience, Mike fully understands, and always carefully (and thoroughly!) explains that big flow numbers are not the holy grail.  He's far more concerned with fuel control, velocity, swirl, and other nuances that can only be successfully manipulated after years of experimenting.   Since he knows I'm putting this page together, he may not even show me the flow numbers (he has a computer-driven Superflow bench).  I did manage to shoot some pix of the unassembled heads and the new rockers.

The exhaust ports required opening up of the SCE copper header gaskets.  The bronze valve guides are visible in the center pic.  Mike has done some very careful shaping of the chamber, especially around the intake valve, to minimize detonation.  I will once again use the standard FelPro composition head gasket.

The shaft rockers are shown after final assembly below left.  Also shown are the rocker cover studs made from good ol' 1/4-20 all-thread from the corner hardware store  The stock steel rocker covers, already clearanced for the previous CompCam Pro Magnums, required additional surgery as shown the the center pic.  With the webs cut away, there was nothing left to align the bolt guide tubes.  Gluing them to the covers didn't work out very well, and trying to align the bolts without the tubes didn't sound like fun, hence the studs.  The rocker stand bar can be seen on the right, along with the 1.45" diameter double valve springs.  Note the rocker roller tip pattern on the second valve from the right.  Stud rockers don't do so well.

The added lift motivated Mike to replace the previous Isky dual springs with a beefier version wound with heavier wire.  Unfortunately for my wallet, the thicker wire drove the spring too close to coil bind with the valves I had (the remaining straight ones), so Mike went with 0.010" longer valves.  He's also using spring cups, viton seals, and titanium retainers.

For pix of some of the final assembly, including the double row timing chain and plug wire routing, click here.