LT1 Engine Build - Heads And Camshaft

Bates also told us to replace the OptiSpark vent tube line. Running the engine without venting the distributor can cause it to fill with ozone and will lead to an early failure. We also took this opportunity to replace several broken and damaged vacuum lines.

Though they say it's impossible to put an OptiSpark on wrong, trust us, it can be done. The pin from the cam is supposed to fit into the square-shaped slot (arrow) on the back of the distributor, but is it possible to get this misaligned. Though it will not fit in the slot, the pin can align with one of the other two wrong slots. If this happens, it will drive the distributor, and the engine will try to start and sound like a traditional geardriven distributor that is off a couple (or several) of teeth.

Here's the trick: When installing the OptiSpark, push the unit on by hand. It should seat fully just by pushing on it. Do not use the bolts to draw it on. If you have to force it on, it's misaligned. Also, using the bolts to tighten the unit could cause the mounting tabs to break. You'll be shelling out big bucks for a new OptiSpark if this happens.

With the new OptiSpark installed, the engine started right up. Our Matco scan tool verified that the ECM was going into closed loop and everything was working normally. We made a couple of dyno pulls to establish our baseline and were pleased with a respectable 282 hp at 5,300 rpm and 339 lb-ft at 3,800 rpm through the stock manifolds and cats.

Next, we swapped in Edelbrock's Performer LT1 heads and Performer-Plus cam package. These heads have been available for several years and are advertised to make about 25 hp more than stock. See the sidebar for a comparison of the cam and head packages. We also installed a pair of emissions-legal Edelbrock headers but kept the stock cats.

We did encounter another problem during the head swap procedure. While unplugging the fuel injectors, we accidentally touched one of the connectors to the manifold, shorting it out and causing the fuel injector driver fuse to blow. We didn't realize this, of course, until after the swap was done and the engine wouldn't fire again. Be warned--disconnect power to the ECM when messing with the fuel injector connectors.