The Willys 161 cu. in. F-Head engine was somewhat of a novelity engine, mixing use of in-block exhaust valves and newer technology overhead intake valves. The midway point between the older flathead engine and the modern overhead valve engine. The Idaho Special used a specially modified engine with a Tri-Carburator set-up and headers.
A factory promotional photo of the tri-carburator set up. This is what we are working towards.
Cameron and Dane will cut open the head using a high powered water jet machine. They will be performing the engine machining on the project, with the exception of the head welding and machining. Third generation machinists! Willys 161 block on the left with magniflux set-up on exhaust valve seat. Dane's hand is on the uncut Willys head, center.
The engine block was determined to be cracked and not usable. Two more engines were obtained, broken down, and crack tested. Both were not usable. A NOS block was needed, but none exist anywhere in the world.
Dave Antram to the rescue. A NOS block for a 1953 Willys 161 F-Head engine DOES exist! Crate removed showing inside pallet.
NOS block that was manufactured in Brazil. Brazil was licensed to produce Willys Aeros, and built cars through 1966. This block had been tucked away by Dave Antram for years, waiting for just the right project. When Dave heard of the Idaho Spcial in need, he jumped to its rescue. Details on the short block build soon, it is being analized by machinists Dane and Cameron.
The head must be cut open to allow for the tri-carb modifications. The Willys 161 had the intake manifold cast into the head. Therefore, to allow a tri-carb set-up, the single intake portion of the head must be cut off. An old head that was too badly rusted to be rebuilt, was cut open to see what it looks like inside.
View showing cut open head and the tri-carb intake manifold. The head will need tapping blocks added to allow the manifold to be bolted onto it.
View showing some preliminary layout marks for the bolt locations. We learned that we needed to leave more "meat" on the head when we go to cut open the second head, a good head.
Here the second head, the "good" head, has been cut open. This view shows what it looks like inside. The section on the right will be no longer be needed. Blocks have bolted on each side of the single carb opening prior to machining the surface to maintain rigidity.
After the rough cut from the water jet, the side the of the head needs to be milled flat prior to welding the custom fabricated tapping blocks into place.
Checking the temperature. The head was preheated in an oven prior to welding to minimize the temperture difference. Also, after the welding was completed, the head was returned to the oven for awhile longer, then the oven is turned off so the head will cool slowly. The last two parts of this process helps stress relieve the weldment.
The head was immediately welded after we took it out of the oven. Here Dick is set up in a comfortable position to enable the best possible welds, using cart handle as an arm rest.
After the "tapping blocks" were welded into position, the ten holes were then tapped.
Cleaning up the sharp edge created after the milling operation.
Dick is doing some edge grinding here after the tapping blocks have been welded into place.
Opening for single carb has been sealed up with a specially lathe-turned stepped steel plug, welded into place. Remaining carburator mounting stud has been cut off rather than leaving an empty hole.
Intake manifold test fitted onto head. The head still needs to have a complete valvejob performed by Dane and Cameron.
We needed to correct a few small cracks at the ends of some welds. Also, Dick didn't like the looks of the top of the "carburator plug", nor the top of the cut-off stud. V-grooves were ground in areas to be rewelded. So, back into the oven it went. Here, it has just been taken out of the oven. Ready for welding.
Here Dick welds for the second time.
After welding and grinding, a test set up was devised to pressure test the head.
Water being added prior to adding 15 pounds of air pressure. The water jackets will recieve no more than 15 psig during operation because of a 12 pound radiator cap being used on the car.
Unfortunately, we had some water leakage, but we could not determine where the leaks were located. We decided to replace the intake manifold with a thick piece of plexiglass.
Here Dick installs the new plexiglass plate. Presuure testing with the new plate revealed the source of the water leaks. Two small cracks at the end of a weld. We will correct this and pressure test again.
Before Dick welded up the two small cracks, it was decided to test install the head/intake manifold/carburator assembly onto the engine block. Woodill ran the racecar without air cleaners. Steve wanted air cleaners to keep the new engine protected, so something needed to be fabricated. Almost no room to work with on the rearmost carburator.
Steve's Superman to the rescue! The rear of the upper hood support was modifed with a circular relief, and new custom made air cleaners were fabricated from scratch.
The bottom plate of the air cleaner drops down around the carburator. Detail of that piece in future photos.
