6. Check Your Volumes
Clearancing your stock Chevy...
Clearancing your stock Chevy block for a double-row timing chain requires removing only a little material around the oil gallery plug bosses.
If you are running a set of old heads-which lots of Pure Stock racers are forced to do-you have to make sure you know whether they've been modified. Your engine machinist can do this for you, but if you can invest in the equipment, it's a great idea to do yourself. After all, if you find yourself and your car in the tech shed, you are the one responsible for everything the inspector finds.
Checking the combustion chamber volume in your cylinder heads will allow you to dial in the exact compression ratio you want for your engine. Also, if your track has a compression rule, or a minimum chamber size rule, your ability to accurately measure chamber volumes can help you get right up to the line for maximum power without breaking the rules.
A kit for checking chamber volumes is available from Powerhouse Tools as well as lots of other sources. Hobby level kits are inexpensive, easy to use, and accurate. And they can help you get a leg up on the competition.
7. Timing Chain Clearance
Measuring the height from...
Measuring the height from the oil pan rail on the block to the bottom of the oil-pump pickup is easy with a straightedge and ruler.
This one is Chevy-specific, but since the vast majority of racers in the Street Stock levels are running Chevy small-blocks, we decided to go with it. Stock engines use a single-width timing chain, but for improved durability and timing stability most racers prefer to use a double timing chain setup (the chain is two links wide). This upgrade is so valuable in terms of helping engines stay together and endure the abuse of racing that double-row timing chain sets are legal almost everywhere.
The problem that comes into play is that stock Chevy blocks don't have the clearance for such a setup. It's close, but if a double-row chain setup is installed in a stock block, you can almost guarantee the back of the chain will rub on the block, which drastically increases the chance of breakage.
The solution is simple: get a die grinder and slowly cut away the material (mostly the top edge of the boss for the upper oil gallery) until your double-row timing chain will fit in place without contacting the block. Obviously, it's best to do this step before you are at final assembly in order to keep metal shavings out of your engine.
8. Watch the Pickup
You can use the same method...
You can use the same method to determine the distance to the bottom of the sump. This distance should be 1/4- to 1/8-inch longer than the distance between the pan rail and the oil-pump pickup to ensure proper clearance.
In most cases, whenever you purchase a racing oil pan, the manufacturer also offers a pickup designed expressly to work with it.
But just because you can get an oil-pump pickup that's made for your oil pan, that doesn't mean you can just bolt it up and go. In order to work correctly, the bottom of the oil-pump pickup (the oil inlet) should be between 1/4- to 3/8-inch off the floor of the oil pan. Any less clearance and you run the risk of the pan pulling up and blocking off the inlet, any more and you can potentially have oil slosh away from the pickup and introduce air into the system-definitely a bearing destroyer.
You can check the distance by installing the pickup into the oil pump and the oil pump on the block. Lay a straightedge level across the bottom of the pickup and measure from the straightedge to the oil pan rail on the block in a line perpendicular to the oil pan rail. Now lay the same straightedge across the oil pan in the area where the pickup will be and measure from the edge of the straightedge straight down to the bottom of the sump of the oil pan. Add 1/8-inch for the oil pan gasket to this measurement.
If the measurement to the bottom of the oil pan is between 1/4- to 1/8-inch greater than your measurement between the pickup and the oil pan rail, you are good to go. If not, you will need to adjust the pickup location and try again until you get the clearance you are looking for.
Well, there you have it-eight engine rebuild tips for the DIY racer.