Rear main seals don't have to leak. Peart locates the seal parting gaps offset from the main-bearing cap contact surfaces to reduce or eliminate risk of leakage. Use Permatex's The Right Stuff sparingly in seal grooves, with a dab at the gaps. | 
We're installing Crane's 349521 hydraulic roller camshaft to reduce internal friction and improve valve-timing events. Both will improve performance. A roller cam allows for a more aggressive profile without sacrificing idle quality and hammering valvesprings. Peart gave our Crane stick generous helpings of engine-assembly lube. Never, ever use moly-based lubricants on cam journals. Use moly coat only on flat-tappet cam lobes, which aids in the break-in process. | 
We set the cam first due to improved access. With the crank in place, it would be harder to set the cam. Peart coated both main journals and bearing with assembly lube, which is better than engine oil thanks to its sticky consistency. It doesn't go away if an engine has to sit for a while. |
Here's a cross-section of the crank/bearing/seal area. We studded the mains with ARP studs for support. This makes our 390's bottom end more bulletproof for those occasional six-grand, wide-open-throttle experiences. Peart has only hand-tightened these studs. They get torqued when we run down main caps. | 
FE big-blocks have a number 5 main bearing cap that's quite involved and leak-prone if you don't install it properly. In addition to main bearing seals, there are also side seals. Peart applies a light application of The Right Stuff between the side seals and main cap before setting main cap in place. He also applies The Right Stuff between the main cap and block in the corners. Don't forget to lube all main bearings and journals with assembly lube. | 
Main stud nuts are torqued in third values--ultimately to 85 ft-lb. Begin at the number 3 cap at 28 ft-lb, then number 2, then number 4, then number 1, and finally number 5. Come back with 56 ft-lb in the same order, and then finally to the 85 ft-lb. Be smooth in your application of torque--no jerking the torque wrench. Be sure to check the crank for freedom of movement (turning) with each cap. If you encounter resistance, clearances must be checked. It means you have improper bearing crush and tight clearances. Peart checks crankshaft endplay using a dial indicator. Endplay should be 0.004-0.0010 inch. Ours is 0.006 inch. |
We have an interesting theory on piston-ring selection. Not everyone shares this opinion, so get ready. There's a developing belief that you should use gapless rings in the top groove and conventional rings in the second groove. This helps cylinder sealing while keeping oil travel and friction where they belong. We invite all theories. Peart checks ring-end gap, which should be 0.010-0.031 inch (ideally in the middle of this range) for top rings and 0.010-0.020 inch (again in the middle) for secondary rings. Ring gaps are adjusted on a special grinder. Did you know only the top ring is a compression ring? Secondary rings are actually oil rings, which carry oil up the wall. Bottom rings wipe oil down the wall. | 
Our Sealed Power forged pistons from Federal-Mogul and Summit Racing Equipment have free-floating wristpins. Because Summit doesn't sell a lot of forged pistons for 390s, these pistons have conventional C-clips. Peart checks the clip installation thoroughly to be sure each is seated firmly in the groove. The wristpins and rod bushings are lubricated with assembly lube. | 
Oil wiper rings are next. Install the expander first, making sure ends do not overlap. They must meet head-on, without overlap. Peart rolls his rings on like this. End gaps should be positioned 180 degrees opposite. |
Top and secondary rings are installed using an expander tool. Never roll these rings on, which will distort the ring. Gaps should be 180 degrees opposite and 45 degrees from each oil ring gap. All ring gaps should be 9, 12, 3, and 6 o'clock. And yes, rings will move during operation. | | |