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-8 Fittings
Pontiac V8 -8 Fittings
When 3/8 Is Not Enough — -8 Fittings for Pontiac V8s
-8 fittings are the step up from -6 when a Pontiac V8 outgrows a 3/8" fuel feed. Russell lists -8 at 1/2" nominal inside diameter and gives its typical use as fuel, oil and water lines, which on a big inch Pontiac usually means a large carburetor, a high output pump, or remote oil filter and cooler plumbing.
Butler stocks Russell -8 hose ends in straight, 45 degree and 90 degree in black and Endura, along with -8 flare to NPT adapters in 1/4, 3/8 and 1/2 NPT. It is the size Holley's Ultra XP bowls and -8AN carburetor inlet kits are built around.
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More About -8 Fittings
1. Deciding whether you actually need -8
Moving from -6 to -8 is a real change in the system, not an upgrade you make for looks. Russell puts -8 at 1/2" nominal inside diameter against 3/8" for -6, and lists it for fuel, oil and water lines.
| Carburetor inlet is the usual trigger | Holley builds 4150 Ultra XP carburetors with -8 O-ring bowls, and sells dual inlet lines with either a 6AN or an 8AN single inlet to feed them. If your carburetor came with the -8 inlet kit, the line feeding it should follow. |
| Pump output | Butler offers BPI-1007FUEL-8, the -8 version of its RobMc mechanical pump to dual inlet Holley kit, with -8 hose ends, -8 swivel elbows, a -8 competition fuel filter and -8 hose. Butler notes it will not work with the RMC-1007 pump, which requires a regulator. |
| Oil, not just fuel | -8 is a common size for remote oil filter and oil cooler plumbing on a big inch build, where you want volume without the routing headache of a larger line. |
| If you do not need it | a mild 400 or 455 on a stock style carburetor is well served by -6. Running -8 everywhere adds cost and makes the lines harder to route for no gain. |
2. Mixing -8 and -6 without creating a leak
Most Pontiac fuel systems end up part -8 and part -6, and the transition point is where people get into trouble.
| The Holley inlet kit question | Butler states that its -8 pump to carburetor kit fits a Holley inlet kit with a -8 end without an adapter, and that if you have the -6 end you should order the -6 kit instead. Check what is on the carburetor before you order. |
| Stepping -8 down to -6 | Butler's instructions for the -6 pump to carburetor kits call out Russell part 660023, a -8AN female to -6AN male fitting, to adapt from a -8 fuel inlet kit down to -6. That one fitting is often all that stands between a kit and a finished install. |
| Do not force a size | -8 hose ends only go on -8 hose, and a -8 flare only seals against a -8 flare. AN flares are size specific by design. |
3. Ends, angles and adapters
Butler carries the -8 pieces in the same three angles as the smaller sizes, plus the pipe thread adapters to land on hardware.
| Straight, 45 and 90 degree ends | available in black and in Endura. A -8 line is stiffer than a -6, so plan the angle at each termination rather than trying to bend your way out of it. |
| -8 flare to 1/4 NPT | for small ported hardware where you still want the larger line. |
| -8 flare to 3/8 NPT | the common landing for fuel logs, regulators and pump outlets that use a 3/8 pipe thread. |
| -8 flare to 1/2 NPT | for larger ported pumps, filters and oil system fittings. |
| Finish | black and Endura are the finishes Butler stocks across the -8 line, so an all black or all Endura engine bay is achievable without hunting. |
If you are unsure whether your combination wants -6 or -8, the carburetor inlet and the pump outlet will tell you. Call Butler with both part numbers and it is a short conversation.
Not sure what your Pontiac needs?
Email our tech team at tech@butlerperformance.com. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.