Race Car Maintenance - Budget Winter Rebuild

So what's the deal here? We now know that worn guides are a power killer, so the next step is finding a cheap fix. First, let's take guide knurling out of the equation because though it is cheap, it certainly is not a fix. This leaves installing bronze guide liners or regular thick-wall bronze/brass guides and having the seat recut. Going to a race shop entails paying race shop prices because of the quality of workmanship typically involved. Figure about 16 bucks a hole and about 100 more for the inevitable seat job. If you take this work to a reputable engine reconditioning shop, you may well walk out with about a hundred more dollars left in your pocket. At this point, an increase in output of about 30 hp could cost you around $250 to $350. So, at some $8-$12 per horsepower, it's a relatively good deal.

You can use another option here. Some replacement part companies such as Engine Tech in Texas (which sells only to the trade) produce valves that have 0.015-inch oversize stems. This size accommodates almost any guide wear. These valves, which happen to be made of 21-4N, are about $6-$7 apiece and can be used to fix the problem with an overall price of as little as $200. But there is one aspect you need to address if you decide to go this route: The valves also have a head that is oversize by about 0.030 inch. This is OK if the rules allow a bigger valve, but if not you will need to reduce the head's size. In addition to this, the keeper grooves have also been moved down so that the stock spring has a higher installed force.

Regarding springs, if you need to upgrade the valvesprings for use with a stock or moderate cam, the Pioneer valvespring (PN RV943X) is an excellent choice, as it has very good dynamic characteristics for a hydraulic cam. It's available from most engine rebuilder shops and is about as cheap as springs get.

Decking a small-block Chevy's block to get zero deck height is definitely a power move, but the machining is not cheap. If the block and head faces are flat, there is power to be gained by using a set of thin (0.022-inch) steel shim head gaskets instead of the usual 0.040-inch thick composite head gaskets. On a low-compression dyno mule that's well used and near stock, a head gasket change like this bumps power from about 286 to 291 hp.

Just as leaking valves costs power, so does a piston, ring, and bore combination that fails to adequately seal. Let's start with the pistons. Many classes require the use of four-valve relief cast pistons because they are usually about as cheap as they come. This is mostly due to volume production rather than shoddy merchandise. In the main, as long as these pistons are not used to excessive rpm with high compression ratios, they will serve long and well. Part of getting the most out of them is making sure they are run at significantly wider than stock skirt-to-bore clearances. This means using typically 0.004- to 0.005-inch clearance between the piston and bore wall as measured at the pin centerline. If the block you use is from a later fuel-injected car, the bores will probably not show much in the way of wear. This means you can get the block honed so that it cleans up at about the size needed for the necessary clearance.

Many blocks show a ridge at the top of the bore where the top ring reverses direction. If you cannot afford to have the block honed, then as long as the ridge is no more than 0.001 inch, you can take a trip to NAPA and get a $25 spring-loaded three-stone "glaze-buster" tool. Use this tool in a suitably sized drill gun to bust the glaze. Then remove the ridge and clean the bore with a coarse Scotch-Brite pad and Gunk.

Even the cheapest set of iron rings will break into the aforementioned bore surface, but here are a few things you should consider. Although requiring much more money, a set of Total Seal top rings will seal better on a less than perfectly round bore than a regular single-piece top ring because the two-piece design is not only gapless, but also conforms to bore errors a little better. For a second ring, a Napier scraper is probably the best choice, followed by a taper face design. Last on the list is a conventional flat-faced ring, which will be OK if the oil control ring has a more aggressive street design. If the bores are worn to the extent that you have to buy pistons, be aware that those designed to accept the wider 5/64-5/64-3/16-inch rings used predominantly prior to the '80s are about half the price of a set with 1/16-inch wide compression rings. Although the 1/16-inch wide items are always preferable, the cheaper, wider ones are OK if peak rpm is only about 5,500. Always use file fit rings, and take great care to gap them to the ring or piston manufacturer's recommended lower limit.