Bullseye Adjustable Exhaust Pulleys for VG30DE(TT)

Adjustable exhaust cam timing

Machining the head or block gasket surfaces moves the camshafts closer to the crankshaft and changes cam timing. On a V engine, the resulting timing change can differ between banks. Adjustable pulleys allow the cams to be degreed to the intended setting.

The Bullseye timing reference

With conventional adjustable pulleys, degreeing the cams moves the original zero reference and may leave different scale readings on the two banks. The Bullseye design adds a third timing element: after the cams are degreed, the outer timing ring can be rotated to align its zero reference. Later adjustments can then be read relative to that degreed setting.

For a fresh build, visually center the bullseye and align the scale zero with the timing mark on the outer ring before degreeing the cams.

Construction and hardware

• Machined from billet 6061-T6 aluminum, with no reused stock parts and no core required.
• Hard-anodized cog, with black-anodized hub and timing ring and white timing marks.
• Each Bullseye pulley weighs 1.29 lb, compared with 2.04 lb for a stock pulley.
• ARP stainless adjustment bolts use oversized heads and washers to limit movement while tightening and protect the pulley surface.
• Helicoiled adjuster holes provide durable threads.

CAS compatibility

The pulleys fit the 1990–1993 Mitsubishi CAS directly. The 1994+ Hitachi CAS requires machining a corner of its casting for clearance. Refer to the related CAS identification technical guide before installation.

Optional stainless cam bolts

BDE-630 and BDE-631 are polished 7 mm × 1.0 mm cam bolts made from 17-4 stainless steel, heat-treated to H900 with 180 ksi tensile strength. Each pack contains four bolts and washers for one pulley; order packs for one or both pulleys as required.

BDE-630 has a 25 mm under-head length for the right pulley or the stock Early Mitsubishi CAS left pulley. Clearance with the Late Hitachi CAS is tight and may require machining. BDE-631 has a 30 mm under-head length and is only for the BDE cam-sync hub used with the BDE crank-trigger kit. Both accessories are currently out of stock.