have finished first in every race in the process of winning a championship.
Bore Finish and Break-In
Regardless of your bore finish specification be very aware that the break-in procedure is important to get the best output and life from your big-block. Over the years I have tried many break-in procedures and felt that they were less than optimal. This led me to develop my own break-in lube and procedure. I did this in conjunction with Oil Extreme. You should note what I have to say about this in Chapter 2, Pistons, Rods and Cranks.
Following my Oil Extreme–based break-in regimen is worth about 7 to 10 hp on a typical 750-horse engine and as much as 12 or more on one of those 1,000-hp-plus builds. This extra power comes with a longer bore/ring life.
Modifications to the Lubrication System
There are quite a few things you should know about the lubrication system in your big-block. You have probably heard of “mains priority oiling” and wondered exactly what it means. If you follow the oil routing from the oil pump, on stock two-piece-seal engine blocks, the camshaft bearings are fed first and from there, the oil is routed to the mains. On one-piece-seal Gen V/VI and aftermarket blocks, the preferable discharge route is where the oil pump feeds the mains first and then the cam bearings.
Although the lubrication system is pretty good on all big-blocks (and better on the later ones), you can perform modifications to improve the system as a whole. The importance of the lubrication system, both in terms of power and reliability, is covered in detail in Chapter 3, Lubrication Systems. Be sure you read it before doing anything to your own block!
Also in connection with lubrication read what is said about timing sets, thrust bearings, and cam buttons in Chapter 10, Valvetrain Optimization.
If the budget is so tight you cannot cover the cost of new ARP bolts, be sure you polish the threads of the ones you have with a wire brush in a drill gun. Only when the threads are very smooth do you achieve the full clamping loads, so don’t shortchange the build on this account.
Fig. 1.10. If valvespring clearance allows it, use low-cost ARP hex-head bolts instead of the 12-point items. For the record, they deliver just as much clamping load.
I am often asked whether or not the heads should be held down with studs or bolts. The easy answer is studs. But they cost a lot more than good hex bolts (from ARP, for example). A set of studs provides a marginally better clamping load than a good set of bolts, such as ARP’s. Also, you need to consider ease of service when the engine is installed. If the engine is equipped with studs, you need to have at least 8 inches of clearance above the studs in the direction that the heads are lifted off the block. If this is not the case, you cannot remove the heads without having to take out all the studs first. This is not the case with bolts. My advice? Unless it’s an “on-the-limits” build, use ARP bolts.
When explaining the use of a stroker crank in my previous Chevy big-block book, I spent most of the time covering what is needed with a 1/4-inch stroker and the Scat cast-steel crank, which is a budget-priced item with great power potential. Whether you choose a cast-steel or forged 1/4-inch-stroker crank for either a 454- or a 502-style block the installation is pretty simple as stroker builds go. For the most part, cutting the block for rod clearance is minimal assuming you are using the right rod for the job (covered in Chapter 2, Pistons, Connecting Rods and Crankshafts). In some cases, the block has enough clearance to allow a 1/4-inch stroker to drop right in but you should not count on it.
Fig. 1.11. This factory 572 is based on a tall-deck block with a 4.560-inch bore and a 4.375-inch stroke. This is a good combo from the point of view of RPM capability and rod-to-stroke ratio.
Let’s focus on strokes of 4.375, 4.500, and 4.75 inches; that is 3/8-, 1/2-, and 3/4-inch strokers. The good news is that almost all 454 and 502 blocks accept a stroke increase of up to 4.5 inches, which is a 1/2-inch increase. If you opt for a forged crank, you should go for the longer-stroke crankshaft because the price difference between a 1/4-inch stroker and a 3/8- or 1/2-inch stroker is virtually nil. That being the case, the minimal amount of extra work for additional block clearance is worth it in terms of results.
As of 2014, I have experience with four 454 1/2-inch-stroker test engines, bored 0.060 over, and each has delivered gratifyingly good results. In spite of having a smaller bore and thus a breathing penalty, the resulting 525-ci build does remarkably well, as long as the combination is right. The principal aspects to focus on are the heads and, most important, a cam spec that suits both the heads and the displacement.
Fig. 1.12. Dart’s short- and tall-deck blocks are almost certainly the most popular choice. The taller deck allows for a longer stroke that is typically worth about 40 ci over the short-deck variant.
Fig. 1.14. Here is a BMP aluminum tall-block. Going from cast iron to aluminum saves about 100 pounds. If big displacement is what you are looking for this particular block can accommodate 632 inches.
Putting a 1/2-inch stroker in a 9.8-inch short-deck block means the rod has to be 6.385 inches long and that’s 1/4 inch longer than stock rods. If the rods are any longer, there is insufficient room for the ring pack. With this length of rod the piston pin height is down to 1.165 and packing a regular set of rings into much less than that
