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We had already purchased a set of Scorpion 1.65 ratio rocker arms to replace our old set of Lunati 1.65 ratio arms that were quite old and getting a little loose in the bearings. We bolted a head to the block and proceeded to check the Scorpion rocker arms for accuracy. What we found didn't make any sense. All the Scorpion arms measured at 1.80 ratio with the light tester springs. How can that be? We tried the Lunati rocker arm and got 1.67 ratio. A stock stamped steel arm measured at 1.52 ratio. We took off the KRE head and bolted on a stock head and redid the tests. Same results with all the rocker arms. We even tested the Scorpions on a small block Chevy along with a Scorpion SBC 1.6 ratio rocker.

Same results. Our rockers measured at 1.80 ratio and the SBC rocker measured at 1.60 ratio. We called Scorpion Performance and informed them of our situation. They were at a loss to explain what could have happened and suggested we send back the rockers arms so they could test them and try to figure out what might have gone wrong. We didn't want to send them back and go through the cost and hassle of crossing the border back and forth from Canada and the US . We settled on the most plausible explanation that the rocker arms were mislabeled 1.74 SBF arms which bolt on to a Pontiac head. Our missing lobe lift had more than come back to us.

At this point we decided to upgrade the heads to take advantage of the increased lift our 1.80 rocker arms would give us. We chose Comp Cams beehive springs # 26918 which were for LS1 heads. At that time Comp didn't have a beehive spring specifically for the Pontiac head. Comp Cams has since introduced spring # 26995 which is a beehive spring for the Pontiac head and installs at 1.70". The # 26918 springs require an installed height of 1.80" and necessitated cutting the spring pockets as well as modifying the spring locators to fit the Pontiac valve guide bosses. We installed the heads using ARP head studs and Cometic head gaskets. This gave us a quench measurement of 0.040" with our zero deck block. We used an adjustable pushrod to determine the right pushrod length and ended up ordering Comp Cams 5/16" hardened pushrods in 9.65" length.

We decided we were going to use a vacuum pump for this engine to control crankcase pressure. Our previous iteration suffered from excessive crankcase pressure and blew smoke as well as unseated the oil dipstick from the tube and blew oil mist all over the engine compartment. We were going to use a Ford air pump but decided not to take any chances and sprung for the real deal. We ordered a Moroso vacuum pump with the right bracket and mandrel drive from Tin Indian Performance . We had to modify the mandrel drive by welding and redrilling the holes that bolt to the damper as we were using a Fluidampr and the holes didn't line up. We eliminated the dipstick tube hole from the block by cutting off a piece of an oil pump driveshaft and pressing it into the block with some gasket shellac. We installed the BOP rear seal with the lip facing the opposite way (i.e. backwards) so the pump can pull more vacuum quicker. A Meziere electric water pump finished off the front end of the engine.

Ignition was to be handled by an MSD billet distributor along with Digital 7 ignition box. We locked the distributor advance mechanism.

For induction, we had a Torker II intake as well as a Holley HP750 and a Prosystems modified HP1000. We wanted to try the Hurricane intake as well and bought one. At this point we decided an intake comparison on the dyno would be a good idea and posted on Performance Years and Classical Pontiac forums for an RPM loaner for the dyno sessions. Glenn Tandy answered the call and shipped us his RPM intake (thanks Glenn).

That's it for this instalment. The next article will be on the dyno sessions and why we had to rebuild the engine yet one more time. Stay tuned...

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