Fuel Injection Intake Manifold

The car is in storage and the manifold project is now back on the bench. The manifold plan is from Total Avance and can be found on the web at http://www.totaladvance.com/manifold.htm. It’s been years since I did any TIG welding and my equipment wasn’t set up to be used in extremely cold weather (the torch is water cooled). The gift of a coolant circulation pump and a few gallons of antifreeze and we were ready to weld. I made a few practice welds and they are sound but not the beautiful even concentric welds that an accomplished TIG welder routinely produces. I really need to practice. The manifold was welded on a jig based on the later TR6 head. The jig is a heavy piece of channel iron with holes drilled matching the head. The tubes are aligned with brass guide plugs bolted to the jig. The pictures show what was accomplished last winter. Next up is to weld cups to the outboard side that will accept the injector tips. Yesterday we ordered a metal lathe for my store that will be turning out injector cups as soon as it arrives. The cups create a seal with the manifold and aim the injectors down the bore of each runner.

The original design uses plates on each end of the manifold to support the fuel rail. I may make some changes to the design and extend the manifold end caps enough to hold the fuel rail in place, eliminating two parts. Friends have been kind enough to supply me with spare injectors and even an assortment of throttle bodies. There are enough injectors from late model VW’s and Volvo’s that I’ll probably use them. The original design uses a Ford 5.0L throttle body. I think the Ford throttle body is a great choice. The Ford body has a larger throat than any of the bodies in my present collection and it may be larger than actually required. I need to do some more research. The photo below shows my current collection. Clockwise starting with the upper left is a two barrel Weber that I believe is from a Volkswagon, next is a Datsun 280Z, a Volvo 240, amd my new favorite the Volvo 850 body. Their throat sizes are: 2X 1.5″, 2″, 2.25″, and 2.125″. Right now I’m leaning toward the Volvo 850 unit as it is extremely simple, has no ports to be blocked, and already has a throttle position sensor. The manifold end plate will be made to accept various throttles so I can experiment.

February 2002

The manifold project is still alive. Winter has been mild here in the Northeast but even mild is pretty cold out in the garage. Recently I turned some aluminium injector sockets that will be welded to the air box. Tonight I welded three of them in place and the ends onto the air box. This weekend I’ll make two more sockets and weld them in place. It’s been years since I did much TIG welding. Back then I could usually get presentable welds but since restarting recently they are strong and solid but not nearly as pretty as I’d like. By the time I welded on the third socket tonight I could see that it was coming back a little. Too bad this little project will be done before I get in much practice. The really ugly welds will get the old hide them by grinding treatment. These pictures show the aluminum sockets and the brass insert used to hold the socket in place for welding. The second picture shows the profile of the fuel rail blank. The cups in the rail will be located and drilled on a friend’s Bridgeport milling machine. The cups need to be accurate to line up with the injector sockets and especially not leak fuel. I won’t embarass myself with any manifold pictures till the welds are cleaned up. Last month another throttle body was donated to my growing collection. This one is a 55mm unit from a 5.0L Ford. Still undecided as to which throttle body to use.

Update: April 2002. The Ford 5.0 throttle body will be used as a starting point.

February 24, 2002

This past weekend my son and I visited our favorite junkyard. It’s one of the few yards that let you wonder around and collect your own parts. We spent a couple of hours exploring as he searched for VW parts and I for fuel injection goodies. I picked uo a throttle body from Peugeot 505 turbo. Still unsure of what throttle body to use yet. The assortment of parts we collected in a 5 gallon bucket came to a total of $10! When the weather warms a bit more I’ll be there collecting injectors, regulators, etc.

Tonight I finished welding the injector sockets to the air box. My TIG welding is getting a tad better but I still need a lot of practice. On Friday I purchased a pneumatic die grinder with a couple of carbide burrs capable of hiding some of those welds. This picture is of the air box with some injectors resting in place. The manifold ends need to be relieved to accept the fuel rail. The rail is just sitting atop the tabs. It still needs to be drilled to accept the injectors. The rail ends are now tapped to accept 1/4″ pipe fittings. I hope to drill the rail this coming weekend.

Update: April 2002. The rail is now drilled to accept the injectors. The injector o-rings are a tight fit into the rail (13.6mm holes). I’m confident there won’t be any leaks.