Our crank was balanced at Gressman Powersports. Scott Gressman handled the job using his Sunnen Pro-Bal balancer.
We began by first weighing all components (pistons, pins, locks, rings, bearings, rods). The Diamond pistons required no correction at all, with the entire set weighing in at 542 grams, +/- 0.5 grams). The Lunati rods, though initially matched to within 0.5 grams, now checked out at an average of 619.5 on the big ends (894.0 g total weight), +/- 1.5 grams, due to our shaving the big-end shoulders for cam and block clearance. Definitely close enough, with no need to fiddle with more lightening on even the heaviest rod.
Once Gressman set up his bobweights, he mounted the crank to his Sunnen Pro-Bal stand and positioned each bobweight on-center at each rod journal. Instead of wasting time measuring the bobweight centering location, Scott saves time by using an in-shop-made spacer that drops over the journal between the bobweight and cheek. With the spacer in place, he simply slides the bobweight against the spacer and tightens the bobweight in place. Cool idea.
Our Lunati crank spun up beautifully, with no need for correction in the front at all. In the rear, the crank wanted a bit of added weight in the rear counterweight. Of course, the desired position was shrouded by the rear flange, so Scott secured the crank (upright) on his Bridgeport and drilled through the flange and into the counterweight, followed by adding a 1″ diameter tungsten slug into each hole (flange and counterweight). The horizontally mounted slugs are preferred as opposed to slugs installed at the counterweight perimeters for obvious reasons…no worries about centrifugal force slinging a chunk of heavy metal. After re-spinning the crank, Scott fine-tuned by shaving a bit of weight (about 10 grams) from the shoulder of the rear counterweight using a die grinder. Our final balance was within 0.08 g, which is tighter than needed, so after a quick journal polish, we were good to go.
PISTON TO ROD ASSEMBLY
The Diamond pistons feature 0.990″ pins for a full-float fit to both pistons and rod small ends. Two spiral locks are required at each pin end (four total per piston). As far as piston orientation is concerned, the larger pocket cuts align to the intake valves, so all right-side pistons are oriented with the intake pockets facing the front of the block and all left-side pistons with intake pockets facing the rear of the block. This places all intake pockets in the upper location relative to the block decks. I’m in the habit of using Foster Tool’s way-cool spiral lock installer tools, but when I realized that I didn’t have a 0.990″ tool handy for our pin bores, I wimped out and asked Scott to hang the pistons for me (I’m embarrassed to admit that I just don’t have the technique to install spiral locks with my fingers).
Of course, Scott slipped them in, gave ‘em a twirl and a tap with his fingertip and secured them in place in a heartbeat.
INSTALLING THE CRANK
Our block and crank requires the use of a 2-piece rear main seal, so I opted for a Victor seal kit. The seal was installed in the block saddle and rear cap, with a small dab of RTV at the mating surfaces.
With the coated Clevite upper main bearings installed to the block saddles and the lower bearings to the caps, all exposed bearing surfaces were coated with Royal Purple Max-Tuff assembly lube (super slippery stuff that sticks and doesn’t drip out).
The center 1/2″ main cap bolts were snugged first, followed by tightening the outboard bolts (caps No. 2, 3 and 4 feature splayed locations). I addressed the center cap (No. 3) first, followed by No. 2, No. 4, No. 1, and then No. 5. All bolts were initially snugged to 20 ft-lbs, followed by 40 ft-lbs, then 70 ft-lbs and to a final 100 ft-lbs. Crank rotation was observed following each tightening step, with the crank rotating with an applied force of about 1.5 ft-lbs once all caps were fully clamped (not bad, considering the new 2-piece rear main seal).
Crankshaft endplay was measured at 0.007″ (spec is 0.006″-0.008″). By the way, this is a good time to mention how impressed I was with the quality of Lunati’s crank and rods. The crank measured out exactly at spec, with no deviations at all. Each main and rod journal was ground exactly to spec, no taper was found at any journal location, the fillets were executed perfectly, the crank showed no runout, and endplay was exactly at 0.007″. Same with the rods…bore sizing was dead-on, center-to-center was consistent at 6.700″ and rod sideplay was 0.012″ (a previous article listed sideplay as 0.0020″ which was a typo…sorry…slip of the keyboard). It’s a real joy to deal with quality stuff such as this. Lunati deserves a salute for their attention to detail.
An oiled brass thrust washer is slipped over the cam nose.
The cam adapter is then placed onto the cam nose. Jesel recommends sealing the rear face of the adapter to the cam nose with RTV.
The cam adapter is secured to the cam with three torx-head 5/16″ screws, tightened to 30 ft-lbs. The bolt threads are coated with RTV. The supplied spanner wrench holds the adapter in place during tightening. Jesel thoughtfully includes a T-45 bit in the kit.
An oiled brass thrust washer is then placed on the cam adapter flange.
To avoid damaging the outer sealing flange, remove the cam gear’s locating key from the adapter.
A pack of three shims are supplied with the kit. Jesel recommends installing all three initially. After checking cam end play, you can then decide if a shim needs to be removed to adjust this.
With the shims in place, the outer flange is installed and secured.
With a dial indictor in place, I checked cam end play. While my initial check found 0.017″, Gressman suggested that he’d rather see 0.006 – 0.010″, so I may remove one of the 0.010″ shims to fine tune this.
Before installing the cam gear, the key must be reinstalled to the cam adapter.
The crank gear is keyed and slips over the snout easily, to a point about 0.384″ short of full fit.
Note the chamfer on the rear of the crank gear. This will nestle against the snout base chamfer.
Using the supplied aluminum driver and a hammer, the crank gear is interference-fit installed fully onto the crank snout.
With the cam gear and adjuster plate in place, the cam gear locking flange is lightly installed (just enough to engage the key). With the cam gear-to-adjuster plate nuts installed by about one and a half turns, the cam gear is tilted forward at the top to allow belt installation (engage the toothed belt onto the crank gear first, then crawl the belt onto the cam gear).
Final installation should feature the top dot of the crank gear aligned with the bottom dot on the cam gear.
Our Jesel belt drive system fully installed. The belt drive remains exposed, with no outer cover needed.
In order to degree our cam, the folks from CamLogic paid a visit to our shop and set up their system on the motor. Shown here is the CamLogic encoder (mounts to the crank), and digital display unit, a cam lobs dial indicator and a piston indicator.
The encoder slips onto the crank snout via an aluminum keyed adapter. The encoder body is then secured (to prevent body rotation) to the block face.