You’ve got questions. We’ve got the answers—the Summit Racing tech department tackles your automotive-related conundrums. This week, we’re diagnosing some small block symptoms.

Q: My vintage GM S-Series pickup has a stock small block topped with a 600 cfm Edelbrock Performer carburetor. When I changed the spark plugs, they had sooty deposits on the electrodes and there was some oil on the threads. There was also a puddle of oil surrounding one of the intake manifold bolts. I tightened the bolt and it stopped the oil leak, but the engine also has a slight lope at idle which gets worse when it’s in gear, plus it pings under acceleration. With all of these issues, I know it may be hard to say exactly what’s going on, but any advice you give me will be greatly appreciated.

J.L. Houston, TX
v8 swap gmc s15 pickup truck

A: Let’s get started by fixing what we know is broken. First, you need to replace the intake manifold gaskets. When they leak, you get oil around the bolts and also on the spark plug threads. To make sure your valves and pistons rings are in good shape, I suggest you perform a cylinder leakdown test with a quality leakdown tester. Finally, worn out cam lobes can cause the lope and engine noise so check out your camshaft for wear and tear.