The crankshaft is installed and torqued to factory specifications. The crankshaft endplay is recorded on the build sheet. The piston pins are oiled to prevent galling during start-up and installed in their respective bores using a ring squeezer and piston installation hammer. The piston hammer is a soft dead-blow-type tool designed to prevent damage to the pistons and coating during installation. The connecting rod nuts are now torqued to ARP specifications included with all their fasteners.
A three-piece double-roller timing chain and gearset are now installed. The camshaft is degreed according to what the engine is going to be used for. It is set up at different specifications depending on if the vehicle has a manual or automatic transmission and if the engine is being built for low- or high-end torque. This is accomplished using a degree wheel and dial indicators.
Once the camshaft is properly installed, the timing cover is installed. The oil pump, having being taken apart and inspected, is coated inside with a film of assembly lube and reassembled. The pump is installed and the bolt torqued to factory spec. The oil pan is then installed and the bolts torqued.
The heads Hesco uses go through the same regime of inspections and washing. The valveguides are measured; the valve stems of the new valves are also measured for uniformity. If the clearances are correct, the machinist will proceed with a standard three- or five-angle valve job. This is dictated by the customer or what the engine is being used for. Very few street engines ever gain any real benefit from a five-angle cut. Once the valve job is finished, the valvespring seats and guides will be machined for the proper spring height and tension. This figure is determined by the valve lift of the camshaft being installed. The amount of material removed from the valveguide will be the same as removed from the spring seat and is done so the valvespring retainer doesn't contact the top of the seal and damage it.
Once the valves have been faced to match the seat cut, a set is installed so the combustion chamber volume can be measured with a device called a burette. It is marked in cubic centimeters and will usually have a liquid volume of 250 cc's. Once the volume is measured, it is compared with the piston and chamber volume to arrive at a compression ratio. The volume of the head gasket is also figured into this equation. The head is then milled to a specified chamber volume for the correct compression ratio. The head is then hand-washed, blown-dry, and assembled. The valve lifters are coated with assembly lube and installed on the camshaft lobes.
The cylinder head is then placed on the block. A small amount of PST liquid Teflon is applied to the threads of each head bolt before being installed in the respective holes. They are torqued in three stages with a final setting of 110 lb-ft on each bolt except No. 11. The final torque for this bolt is 100 lb-ft. Assembly lube is applied to each end of the pushrods and they are installed with one end on each valve lifter. The rocker arm assemblies, having been washed and dried, are next in line. The rocker pivots are coated with a film of assembly lube, as is the tip of each valve stem.
The rocker arms and pivots are installed in pairs. A dial indicator is used during the bolt tightening sequence to measure lifter preload. Too much preload and the valve will be held open and the engine rotates, resulting in a loss of compression. If adjustment of the preload is necessary, shim kits are available from camshaft manufacturers, or AN washers in 0.030 and 0.060 may be used. This measurement is recorded on the engine build sheet. Refer to the Jeep manual for the specifications on bolt torque and preload. Once the rocker arms are properly adjusted, the valve cover is installed. The oil filter adapter is installed with a new oil filter that has been filled with fresh oil. A mechanical oil pressure gauge is attached to the oil pressure sending unit block next to the oil filter. The engine is filled just below the add mark of the dipstick. The oil pump shaft is turned by hand until pressure registers on the oil pressure gauge. The pressure is also recorded on the build sheet. Every specification of an engine is recorded on the engine build sheet.
The engine is then sent to the engine dyno room, where the camshaft will be properly broken in and the vitals recorded on the dyno computer. Once the camshaft is broken in and the engine inspected, it will be run to ensure the power levels are as expected for that particular engine combination. Obviously, we can't cover everything in this story - and there are trade secrets that drastically increase performance that Hesco told us not to reveal - but once the operator is satisfied the engine is of the expected power and quality, it will be removed and installed or shipped to the customer.
Source
Hesco
205/251-1472
www.hescosc.com