What happens when you have a numbers-matching block that has been bored to its limits? Or perhaps there’s cylinder wall damage from a runaway connecting rod or a busted ring. Because new and used Chevy small- and big-block engine blocks are widely available there’s little reason to save a damaged block unless there’s real value in the block. The same can be said for late-model LS blocks. They are plentiful new and used.
The best reason we can think of for saving an engine block is if it’s a numbers-matching engine block from a Corvette with a high resale value on the auction block. Having a numbers-matching engine and driveline is critical to resale value.
You can save an engine block with new Melling cast-iron cylinder sleeves from Summit Racing Equipment. What’s more, you can buy one cylinder sleeve or all eight, depending upon the extent of your needs. We’re working with Dave Akard of Burbank Speed & Machine who is sleeving a 327 block from a 1966 Corvette roadster.
Dave tells us the decision to sleeve a block depends upon perceived value of the vehicle or engine. A standard production small-block Corvette driver in average condition isn’t going to be worth the expense of a sleeving, which can cost upwards of $200 per cylinder depending upon location. In this case you’re better off opting for a new Chevrolet Performance block from Summit Racing Equipment.
Melling cylinder sleeves from Summit Racing Equipment are centrifugal cast-iron cylinders engineered to tolerances down to one half of one thousandth of an inch on modern CNC equipment for precision accuracy. The centerless outside diameter grinding process guarantees a part that is perfectly round and the iron used in these cylinder sleeves offers a Brinell hardness of 241-293 and machines easily with strength and durability similar to that of ductile iron. The average tensile strength of these cylinder sleeves (45,000-50,000 psi) is considerably greater than standard OEM-style ductile iron sleeves. Not only are these sleeves good for damaged or oversize bores, they also deliver strength if you’re going racing and desire durability from an original Chevrolet block.
There are different approaches to installing cylinder sleeves in a worn block. Some machine shops put cylinder sleeves into a deep freeze to get them down to a size where they’re easier to press into the block. Dave bores out each cylinder to where the sleeves can be pressed into the block with ease to where each is an interference fit and will not move. He leaves a lip at the bottom of the cylinder to where there’s no movement. This is a proven approach he has used for many years. Your local machine shop may have a different approach, which should be confirmed ahead of time. You want a machine shop with a proven reputation before handing them a valuable block. Vette
1. We’re working with an original, numbers-matching 327 block from a 1966 Corvette roadster. The cylinders have already been machined to 4.040 inches and should not be bored any further. Some builders are comfortable going to 0.060-inch oversize, which in Dave’s opinion is discouraged.
2. Dave Akard of Burbank Speed & Machine was unable to save this block at 0.040-inch oversize. He contacted the owner who decided to sleeve the block. The first order of business will be to bore the block large enough to accommodate Melling cylinder sleeves.
3. Dave measures the cylinder sleeve’s outside diameter, 4.1905 inches, to set up the boring bar. The cylinders will be bored for an interference fit of 0.001-0.0015 inch, which places just enough of a squeeze on the sleeve to provide security.
4. The real beauty of sleeving a block is you can start all over again with standard bore and any piston of your choice. Dave has chosen standard Speed Pro coated and forged pistons for this build, which are available from Summit Racing Equipment. These cylinder sleeves are a pinch undersize inside diameter (3.970-inches semi-finished) to give you room for machine work and the clearances desired.
5. Dave Akard of Burbank Speed & Machine sets up the boring bar to cut the existing cylinder bores, which is performed individual machining steps to where there’s a lip at the bottom of each bore for support.
6. Once the boring bar has been set up, Dave begins cylinder boring, with 0.030 inch being machined out with each pass for a total cut of 0.1890 inch.
7. Here’s a closer look at how finite each cut is. Dave stresses these cuts must be made 0.030-inch at a time to keep heat and distortion down.
8. As Dave makes each pass, he checks the bore size with a dial-bore gauge.
9. As you can see, a considerable amount of iron has been cut, leaving a 0.0945-inch support lip at the bottom of each cylinder. This support lip keeps the cylinder sleeve stable.
10. Dave uses Loctite 609 retaining compound to bond the cylinder sleeve with the existing bore for added security. Permatex High Temperature Sleeve Retainer is also very effective for this purpose. Also, some blocks may cut into water jackets, which may require a JB Weld epoxy to seal out the coolant. Note the cylinder wall rough cut from the boring bar, which improves the sleeve-to-cylinder wall bond.
11. Retaining compound is also applied to the cylinder sleeve for a more solid bond with the cylinder wall.
12. The cylinder sleeve has been driven into place and is seated against the bottom lip. Because these cylinder sleeves apply to a variety of applications, the excess sleeve will have to be removed with the boring bar.
13. Dave uses the boring bar with an appropriate cutter to cut the cylinder sleeve down as shown to get it flush with the block deck.
14. Once each cylinder sleeve has been cut down close to the block deck, the deck gets a final shallow cut just to remove each cylinder sleeve.
15. When the deck milling is complete to get the cylinder sleeves flush, the next step will be to clean up the ragged edges of each sleeve, coupled with piston match honing.
16. The block deck has been milled smooth to remove any distortion and get the sleeves flush.
17. Down under you can see where the cylinder sleeves meet the lip for solid security. This 327 block is as good as new and even stronger thanks to the installation of these Melling sleeves.
18. Here’s another look at our 327 block, which has been fully machined and readied for assembly. GE Glyptal has been applied to the valley to both seal the iron and improve return oil flow to the pan.
19. We’ve just sleeved a “dry sleeve” block where the cylinder sleeves are not in direct contact with coolant. This is a “wet sleeve” aluminum LS block where the cylinder sleeves are in direct content with the coolant. Wet sleeve blocks call for thicker cylinder sleeves.