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Using ARP moly lube on our stud threads and nuts (and on both sides of each washer), all nuts were tightened to a value of 65 ft-lbs, with the exception of the four special inboard (lifter valley side) studs, which were tightened to 45 ft-lbs.
Note: Because the four lower outboard studs (the shortest studs) on each head are shrouded by the exhaust port bosses, an offset adapter was needed to gain access to the stud nuts. I used a 1/2″ 12-point extension from Snap-On, that features a center-to-center length of 2″ ($36 from my local Snap-On dealer). This flat dog-bone style extension features a 12-point 1/2″ box wrench at one end and a female 3/8″ square drive at the opposite end.
Because an extension was used with the torque wrench, it was necessary to lower the setting on the torque wrench to compensate for the increased leverage effect of the extension.
To determine the correct torque wrench setting for these four lower stud nuts, I used the standard formula as follows:
C= D x (A divided by A + B)
A = the length of the torque wrench, from center of the head to center of the grip handle
B = length of the adapter extension
C = the torque wrench setting
D = desired torque value
In our case, the length of my torque wrench is 14.5″
The length of the Snap-On extension is 2″
The desired torque value is 65 ft-lbs
So,
C = 65 x (14.5 divided by 14.5 + 2)
C = 65 x 0.8787
C = 57.12
In this case, our torque wrench setting was 57 ft-lbs.
HOUSTON, WE HAD A PROBLEM
Although it would have been easy to avoid admitting problems or dumb mistakes, I’d never do that. After installing the heads, and with the Jesel rockers and Manton pushrods in place, I started setting valve lash and soon realized that something was rotten in Denmark. Even though we set the springs at the recommended height, I discovered that, due to the extreme cam lift, the intake retainers contacted the top of the intake guide seals just before the lifters climbed up to the lobe peaks (on the intakes only). The fix requires cutting the intake guides down (overall height and shoulder height) by about 0.130″.
This isn’t a fault of Dart’s guides. Rather, the problem arose as a result of the extreme total valve lift of our oh-so-nutty cam profile (lift at the valves is an insane 0.968″ intake and 0.925″ exhaust). This is an easy fix if you’re aware of it early on. I used a 1/2″-I.D. cutter mounted to an 11/32″ pilot on a drill to reduce guide overall and seal shoulder height in one operation.
Sorry about that. Looking back, I now know that I should not have assumed anything (yeah, I know). I should have installed checker springs in all 16 locations and performed a complete roll-over. I know I’m not the only one to have screwed up like that, but it’s embarrassing nonetheless. I’d rather ‘fess up and reveal the problem, in an effort to help someone else avoid the same glitch. I’ve had the heads on and off so many times I’ve lost count. Oh well, what’s one more?
Our guide height (protruding above the bare spring seat) was originally 0.625″. Using a guide cutter (allowing me to cut overall height, shoulder height and chamfering the top simultaneously), I reduced exposed height to 0.478″, with a total height removal of 0.147″. This provides adequate clearance for both intakes (where we needed it the most) and exhaust locations, where the retainers were just beginning to touch the seals.
Upon close inspection of the operating valvetrain, we re-set our valve spring installed height for a bit of added insurance against potential coil bind, changing our installed height from the previous 2.100″ to 2.150″. This was partially accomplished by switching to +0.050″ Crower valve keepers on the intake locations. It should come as no surprise that the domino effect bit us on this change. Because of the beefy dimensions of the +0.050″ keepers, our intake lash caps fit a bit tight and were too close (for my taste) to the top of the keepers. To provide a comfy fit, I carefully ground 0.010″ from the bottom of the lash caps, and spin-polished the cap outside diameter to prevent the outer walls of the caps from rubbing on the upper I.D. of the new keepers. Once I did that, the caps fit just fine and dandy.
With all of the pushrods and rockers in place, I adjusted initial valve lash at 0.20″ at the intakes and 0.022″ at the exhaust valves.
INTAKE MANIFOLD
During test-fitting, I realized that our Profiler Performance tunnel ram intake manifold, P/N 187-10, sits a tad high at the Dart block’s rails (a common situation simply due to the tall-deck nature of our block). Rather than try to fill the approximately 3/8″-plus void with RTV alone, I obtained a pair of Dart’s billet machined aluminum end-rail spacers, P/N 62220006. These spacers are 3/8″ thick (they measured exactly 0.375″), with ends angle-cut to match the decks.
Each spacer features three 0.183″ holes. In order to prevent the spacers from walking out fore or aft (a possibility if I relied on RTV alone), I drilled two holes in the block rails (just using the two end holes at the spacers) using a 1/8″ (measured 0.123″) drill and installed 1/8″ roll pins in the block rails. I drilled to a depth of 0.375″ and cut the pins to a length of approximately 0.690″, leaving about 0.330″ protruding above the block rails. This allows the spacers to be coated with RTV and securely located onto the rails. Since the holes in the billet spacers are larger in diameter than the roll pins, this allows the spacers to self-center left-to-right when the heads are installed.
For intake manifold port gaskets, we had a choice: use blank gaskets (cut to fit) or use Dart’s P/N 65002155 intake gaskets. These are actually designed for the 14-degree Big Chief heads, but fit great on the 11 degree heads with a tiny bit of trimming at the bottom of the port holes and water jacket holes.
Gasket thickness is 0.060″ (0.120″ thickness is also available to accommodate funky fitments). Note: Dart told me that when ordering the intake gaskets, the Dart part number references one gasket, so if you order, make sure to order two of P/N 65002155. The end-rail spacers are already packaged as a pair.
With gaskets in place, I test-fit the intake manifold. I then checked intake port alignment (thanks to the straight-shot and huge intake runners, the port-to-port matchup was easy to view). After marking a few very minor excess-material locations on the head port openings, the heads were again removed and relieved using an electric die grinder and mini belt sander. Only a few small touch-ups (mostly on vertical port edges) were needed, which basically resulted in a chamfered blending of the vertical port edges.
Note: since Profiler’s intake manifold features very healthy 0.925″-thick mounting flanges, “standard” bigblock Chevy intake bolts will be too short. I used twenty ARP 12-point stainless 3/8″ x 16 x 1.5″ bolts (obtained by purchasing four 5-packs, under ARP P/N 613-1750).
Since I didn’t have the correct MSD distributor to clear our intake manifold, I used a spare Chevy distributor that was lying around in our storage room to help with manifold indexing. With the intake manifold dry-fitted (bolts loose), I mock-installed the distributor. This allowed me to “center” the intake manifold, with any possible variance in bolt hole tolerance position dictated by the distributor. After verifying proper fit, I then removed the distributor and manifold, applied dabs of Permatex The Right Stuff RTV on the top surface of our block rail spacers and in the corners, placed the manifold in position, mock-installed the distributor and then tightened the manifold bolts to a final value of 35 ft-lbs. (I started off at 10 ft-lbs followed by 20 ft-lbs and finished at 35 ft-lbs).
By the way, the Profiler intake manifold fit beautifully. Hole lineup was dead-on, on both the lower flanges and on the top plenum cover. The Profiler top plenum cover (they offer these in single and double-carb versions) attaches via a series of 1/4″ x 20 3/4″ stainless socket head cap screws and a rectangular stainless-steel reinforced gasket (thoughtfully provided by Profiler). I didn’t need to fudge a single mounting hole.
I installed polished stainless steel ARP Dominator carb mounting studs P/N 400-2414 onto the top plenum cover. These feature a handy bullnose tip, allowing nuts to be dropped on easily with no-muss thread starting. This is the only way to go, for both carb studs and distributor hold-down studs. The bullnose is deep enough the capture the nut (no more dropping nuts and wondering where they went), and thread starting is butter-smooth at the first try. Using an open-style carb gasket, I installed the Holley 1150 cfm Dominator, P/N 0-80673, snugging the four mounting nuts to an initial value of 58 in-lbs. in a criss-cross pattern (I can always increase this later if needed).
In order to provide an upper coolant hose connection, I installed a billet aluminum thermostat housing that features a -20 AN male end. I may switch this out to a slip-neck style for the dyno. For sealing, I used Victor’s way-cool C21331 thermostat housing gasket. This re-useable gasket features a hefty aluminum core with silicone rubber seals on both sides. This gasket is very beefy and will withstand repeated servicing.
Tags: ARP, ASSEMBLY, CYLINDER HEADS, DART, INTAKE MANIFOLD, JESEL ROCKERS, PROFILER
