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Project C5X Gets A New Head And Cam Upgrade For Some Serious Power

Alan L. Colvin Mar 1, 2010 0 Comment(s)
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Along with our custom Comp Cams camshaft, we also decided to use Comp Cams GEN III High Energy OE -Style Hydraulic Roller lifters. We also tapped Comp for one of their GEN III Adjustable Timing Gear Sets that features a pre-stretched heat-treated double roller chain and has a 3-keyway crank sprocket for an additional 4-degree incremental adjustability. Comp also sent us their GEN III Crankshaft Socket, Degree Wheel, Cam Degree Tool and TDC Stop to use during the build. These tools are invaluable when building an engine of this caliber. Dimmit Chevrolet of Clearwater, Florida, also provided all of the bolts, gaskets and even a GM PF46 Oil Filter needed for the rebuild.

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As we said previously, we decided to do a custom C4orce grind camshaft to take full advantage of all of our parameters. This camshaft is one of several C4orce camshafts that we have designed over the last couple of years that Comp Cams has built for us. We will talk about the specifics of each of those cams in a future issue of Corvette Fever. What we can say at this point is that this particular camshaft uses a larger lobe separation number than most for better idle quality. One thing to always remember when choosing a cam profile is not to go overboard if the car is to be driven (especially daily like Project C5X is) on the street. The LS1 engine is so responsive to small changes in cam profiles that you really don't have to get radical with your upgrades. After we had the engine completely torn down, and the original heads and cam removed and cleaned, we then began the installation of the new Comp cam. With our new Comp Cams GEN III Adjustable Timing Gear Set (with their 3-keyway crank sprocket for an additional 4-degree incremental adjustability) and new GEN III Crankshaft Socket, Degree Wheel, Cam Degree Tool and TDC Stop, Geoff Skorupa of NLP then degreed the camshaft in. He recommends that all custom camshaft installations should be degreed per the manufacturers' cam card specs. Now we were ready for the cylinder head install.

We knew from the beginning we would have to modify the new World heads to fit this particular application and part of that was angle milling the stock castings to arrive at a 10.5:1- 11:1 compression ratio. As we mentioned before, due to pushrod clearance issues, material had to be taken out from the casting which opened up into the intake ports. This had to be repaired by welding a new wall area around the pushrod opening to alleviate the problem and was our second modification. Upon installation of the cylinder heads to the block, we ran into some more modification issues. Everything looked good up until the installation of the Comp Cams Ultra-Gold GEN III Rocker Arms. We couldn't even tighten down the rocker arms because the top valve cover rail was interfering with the rocker. We then tried installing the stock rocker arms and quickly found that we still had the same top valve cover rail interference issue. There was just no way that the stock rockers would fit on the World heads. The only alternative we had was to hand grind the valve cover rail area on the cylinder head above each rocker arm to get enough clearance for proper rotation of the rocker arm.

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Once all the rocker arms were installed and properly adjusted, the next issue we found was during the installation of the valve covers. The stock valve cover bolts bottomed out into the casting before the valve covers were tight, so we had to decrease the length of the valve cover bolts to properly tension the valve covers. After installing the headers and trying to install the coolant sensor into the driver's side head, we realized the sensor hole in the head had been drilled too close to the exhaust header flange, making it necessary to hand grind the header flange for clearance of the installation of the sensor. While installing the intake manifold, we then found interference between the bottom of the intake and the heads, thus not allowing the intake ports to seal properly. Out came the hand grinder again, while we removed material from the bottom of the intake for proper fit and seal of the manifold. The intake manifold bolts also had to be shortened for proper installation of the manifold. After this problem was rectified, the rest of the engine was buttoned back up and we headed for the dyno.

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