Holley’s quick change jet kit for its 4150 carburetor is really valuable at the track. But depending on the engine, access to the jets through the fuel bowls can be very difficult. In the case of the SBC, the distributor restricts access through the rear bowl. And the radiator hose often restricts access through the front bowl. Some racers have cut the Holley tool shorter to try to make it work. But I need to apply full, firm pressure on the tool to be able to keep the jet in place -- particularly during jet removal. That usually means removing the carburetor. This simple fixture will enable access to the jets with just partial removal of the carburetor. You unbolt the carburetor, lift it up, place the fixture on the intake manifold and rotate the carburetor on the fixture to align with the positioning studs. It does not need to be bolted down. The only attachments that must be removed at the carburetor are the fasteners to the intake and the throttle linkage. Fuel lines, vacuum lines, etc usually have enough slack to remain in place. The fixture holds the carburetor firmly at an angle to allow clear access to the front and rear bowls. The plywood construction prevents scoring of metal surfaces. And the fixture covers the intake manifold to prevent accidental dropping of foreign objects into the intake. Typical interference at front and rear of Holley 4150 series. Construction is simple, from two pieces of scrap 3/4" plywood. Note how top piece that holds the carburetor is angled, as desired. The 1/4 x 20 bolts simply are to hold position. Combined thickness of the plywood pieces needs to be sufficient to keep carburetor base clear of the manifold bolts. Rough dimensions. In position, the fixture holds the carburetor at an angle. Access to front bowl. I may lengthen the fuel line to be able to leave it attached during jet change. Access to the rear bowl. Lots of clearance with the distributor now.
where is Paul Harvey when you need him? 1. You have cheater bowls with plugs to access the jets 2. you will still need to drain the bowls, where is you trick fuel pan? 3. Miss your fuel pan and you dump fuel into and onto your manifold through the stud holes. 4 The hundreds of times I changed jets in the pits I never left the carb on the engine, fuel vapors will ignite. (ask me how I know being a vehicle fire investigator)
All true. My intent with this is only to supplement the existing Holley quick-change kit, by providing better access to the plugs on the quick-change bowls. I didn't intend to suggest to replace or to eliminate any parts of the Holley quick-change kit/tools. Draining the fuel bowls before removing the access plugs is given, and the Holley drain cup works well for that..
simple setup that makes sense. too bad the keyboard critics have to throw water on a great idea...just to show how smart they are. Is the intent to discourage Finn or anybody else from posting a Tech Week idea in the future? but at least you can always remind us how important you are as a Vehicle Fire Investigator. good job Finn!
http://www.jalopyjournal.com/forum/threads/vote-now-tech-week-october-2015.995188/ Short time to vote
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