Chevy Small & Big Block V8 Pro Series Ready to Run Distributor with Adjustable Collar

• Adjustable collar — precise timing lock-down, prevents timing shift under high-RPM operation

• Fits SBC Gen. I 262–400 and standard deck BBC 396, 402, 427, and 454 — carbureted

• External coil required (35,000V+) — no ignition box needed, tach output cable included

• Mechanical and vacuum advance — 3 bushings, 4 springs, vacuum block-off plate included

The TSP Pro Series Ready-to-Run Distributor with Adjustable Collar for the Chevy SBC and BBC delivers everything in the TSP Pro Series Ready-to-Run (JM7715) — advance curve tunability, tachometer output, vacuum advance block-off plate, and an integrated ignition module requiring no external ignition box — plus a precision adjustable collar that locks the distributor in position after timing is set. This is the top of the TSP Chevy carbureted distributor lineup for builders who want Pro Series performance with the timing precision and security of a slip collar.

What the adjustable collar adds: The slip collar clamps around the distributor housing at the engine block, allowing the distributor to be rotated for precise timing adjustment and then locked firmly in position. Standard distributor hold-down clamps rely on a single bolt against the outside of the housing — under high-RPM operation and engine vibration, this can allow the distributor to shift and alter ignition timing. The adjustable collar eliminates this by securing the housing in a precise, fixed position once timing is confirmed. For the $35 premium over JM7715, the collar provides meaningful timing stability on high-performance street builds and track-day vehicles where timing security matters.

Distributor rotation is clockwise — standard for the Chevy SBC and BBC. An external ignition coil rated at 35,000 volts or higher is required — the coil is not included. No external ignition control box is needed — the ignition module is integrated internally.

Three advance bushings and four advance springs are included for mechanical advance curve tuning. A vacuum advance block-off plate is included for performance builds where vacuum advance is not needed. A tachometer output extension cable, power extension cable, and color-matched spark plug wire retainer with screws are also included.

Adjustable Collar vs. Standard Hold-Down — What It Actually Does
On a standard distributor without a collar, timing is set by rotating the distributor housing and then tightening a single hold-down clamp bolt against the outside of the housing. This works adequately on most street applications, but the clamping force is indirect — the bolt presses against one side of the housing and relies on friction to hold position. Under sustained high-RPM operation and engine vibration, this friction can be overcome and the distributor can rotate slightly, shifting ignition timing from where it was set.

The adjustable collar on this distributor solves this directly. The collar is a precision ring that wraps around the distributor housing body and clamps with even, circumferential force — locking the distributor in the exact position where timing was confirmed. The collar can be loosened for adjustment, the distributor rotated to the correct position, and then the collar re-tightened to lock timing precisely in place. This provides a significantly more secure hold than a standard clamp, particularly under high-RPM and high-vibration conditions.

Pro Series R2R vs. Pro Series R2R with Collar — The $35 Decision
The standard Pro Series Ready-to-Run (JM7715) and this collar version (JM7716) are otherwise identical — same integrated module, same advance kit, same advance block-off plate, same tachometer output, same external coil requirement, same engine fitment. The $35 premium is entirely for the adjustable collar. If timing security under high-RPM conditions is a concern in your build, this is a straightforward upgrade. If a standard hold-down is acceptable for your application, JM7715 is the correct unit.

Performance Benefit
The integrated circuit board module and magnetic pickup deliver precise, repeatable spark timing without the wear and drift of points-based systems. Three advance bushings and four advance springs allow the mechanical advance curve to be matched precisely to your engine's camshaft, compression ratio, and carburetor calibration. A vacuum advance block-off plate is included for builds preferring full mechanical advance only. A tachometer output extension cable simplifies aftermarket tach wiring without adapters.

What does the adjustable collar do and why would I want it?
The adjustable collar is a precision slip ring that clamps around the distributor housing after timing is set, locking the distributor in its exact position with even clamping force around the housing. Standard distributor hold-down clamps apply force from a single bolt against one side of the housing, which can allow the distributor to shift under high RPM and engine vibration, changing ignition timing. The adjustable collar eliminates this risk by securing the distributor exactly where timing was set. For high-performance street builds, track-day vehicles, and any application where timing stability during sustained high-RPM operation is important, the adjustable collar is a meaningful upgrade over a standard hold-down clamp.

What is the difference between this distributor and the standard TSP Pro Series Ready-to-Run (JM7715)?
These two distributors are identical in every respect—same integrated ignition module, no external ignition box required, same engine fitment, same external coil requirement, same advance tuning kit, same vacuum advance block-off plate, same tachometer output, and same specifications. The only difference is that this distributor includes an adjustable slip collar, while JM7715 does not. The adjustable collar provides a more secure distributor hold-down under high-RPM and high-vibration conditions. If maximum timing stability during sustained performance driving is important, choose this version. If a standard distributor hold-down is sufficient, JM7715 is the correct choice.

Does this distributor require an external ignition box?
No. This is a Pro Series Ready-to-Run distributor with an integrated ignition module. No external ignition box, CDI unit, points, or condenser is required. An external ignition coil rated at 35,000 volts or higher is required, but the coil is not included. This distinguishes it from the TSP Pro Series Pro Billet distributors (JM7601 and JM7601-1), which require an external ignition box.

What engines does this distributor fit?
This distributor fits the Chevrolet Gen. I small block V8—262, 265, 267, 283, 302, 305, 307, 327, 350, and 400 CID—and the standard-deck Mark IV big block—396, 402, 427, and 454 CID—in carbureted applications. It is not compatible with tall-deck big block engines, governor-equipped applications, LS engines, or EFI systems. Distributor rotation is clockwise.

What is included with this distributor?
This distributor includes three advance bushings and four advance springs for mechanical advance curve tuning, a vacuum advance block-off plate in black, a tachometer output extension cable, a power extension cable, a color-matched spark plug wire retainer with mounting screws, and an adjustable collar integrated into the distributor housing.

Can I tune the advance curve on this distributor?
Yes. Three advance bushings and four advance springs are included, allowing you to adjust how quickly mechanical advance comes in as engine RPM increases. This is the same advance tuning kit included with JM7715. The adjustable collar improves timing stability but does not alter advance tuning capabilities.

Does this distributor have a tachometer output?
Yes. A tachometer output extension cable is included for connecting an aftermarket electronic tachometer. This distributor does not include a mechanical tachometer drive.

What direction does this distributor rotate?
This distributor rotates clockwise, which is the standard rotation direction for all Chevrolet Gen. I small block and Mark IV big block V8 engines.

Does this distributor include vacuum advance?
Yes. Both mechanical (centrifugal) advance and vacuum advance are included. A vacuum advance block-off plate is also provided for performance applications where vacuum advance is not desired.

What type of distributor gear is included?
This distributor includes a steel distributor gear. It is most compatible with cast iron hydraulic or solid flat tappet camshafts. For roller camshaft applications, consult your camshaft manufacturer for the recommended distributor gear material before installation.

Do I need to set ignition timing after installation?
Yes. Set base ignition timing with a timing light after installation. Loosen the adjustable collar, rotate the distributor to the desired timing position, then tighten the collar to lock the distributor securely in place. For most carbureted SBC 350 applications, a starting point of 8–12 degrees BTDC at idle is a common reference.

Is this compatible with a 6-volt system or generator?
No. This distributor requires a 12-volt electrical system with a charging alternator. It is not compatible with 6-volt systems, generators, or ballast resistors.