5. Balancer

An important note of caution before you break out the timing light—old original harmonic balancers, which have timing marks, may be way off. "The rubber cracks—it's 35 to 50 years old or more—and that outer ring starts to wander. I've seen a lot of Pontiacs where that outer ring has come way out and it's getting into the pulleys, or way back to where it's digging into the timing cover."

You can check it by pulling the spark plug from the No. 1 cylinder (driver-side front) and inserting a small probe to feelthe piston as it rises to top dead center. When the piston is at the top of its travel, the timing pointer should be at 0. If it's anywhere else, you need a new balancer.

Dan's Tip: Ignition timing is critical. Confirming the accuracy of the timing marks on the harmonic balancer is a must for top performance. Top Dead Center (TDC) indicated on the balancer must match actual TDC of the piston.

6. Cam/Valvetrain

Just about every engine these days has had at least one rebuild, and the machining involved can change valvetrain geometry. An undesired effect of milling the block and heads is that the correct pushrod length has now become too long, causing the lifter plunger to bottom out (left) when torqued to factory spec and using stock rocker studs.

Dan says: "Pontiacs use a shouldered rocker stud. The factory setup is to tighten the rocker until it hits that shoulder, then torque the nut to 20 ft-lb. But once you start cutting the heads and deck, doing that can jam that pushrod down into the lifter until it almost bottoms out. You don't want to do that."

The remedy is simple. "I like using ARP studs, and swapping out the stock rocker nuts for polylocks, or crimp nuts that Chevys and AMCs use. They grip the threads so they stay where you set them and don't back off. I tighten the nut down to zero lash—where all the slop is taken up—then go another half turn." That gets ideal adjustment on every valve, without relying on lifters to create the proper slack.

Dan recommends the customary three-angle valve job, and also finds that going to extremes with polished and neck-down valves are not worth the cost in a street engine.

Dan's Tip: There's little, if any, room for larger valves on heads with 2.11/1.77-inch valves from the factory. On '73-'74 non-Super Duty heads, there's room to replace the factory 1.66-inch exhaust valve with a 1.77 if you need better top-end breathing, but don't expect huge gains, and understand that this mod is not legal for the Pure Stock Drags.

7. Exhaust Manifolds and Systems

If you're going concours-correct, you have to run what the factory gave you, and some exhaust manifolds are better than others. But don't sweat it. Dan has proven on the dyno that there isn't that much difference in power between the high-flow manifolds and the really lousy emissions logs.

"I ran a '69 Firebird Ram Air III—a D-port engine that came with long-branch manifolds—on the dyno. I wanted to start with '69 standard logs, but I didn't have any. All I had was '75-and-up emission logs, which are even worse. I ran those first, then switched to the nice long-branch manifolds. The difference—9 horsepower. That's it. [Pontiac engine engineer] Mac MacKellar told me that he came up with that same 9 horsepower in his dyno tests of the day."

Like cam specs, moderation works well on exhaust-pipe diameter. Dan says: "On a 350, 2.25-inch is more than enough. On 400 and up, 2.5-inch works. On 455s, you could go with a 3-inch, but I think that is overkill unless the engine is really modified."

Dan's Tip: An H-pipe or X-style pipe quiet the noise and add a better tone, but as far as power gains, the dyno tests he's been involved in show mixed results. H-pipes and X-style pipes are thought to boost mid-range torque, but Dan can't point to his own dyno tests to confirm it.

8. Oil

Based on recent, exhaustive research, Dan has changed the motor oils he uses. "I use Brad Penn 30W break-in oil just to break in the cam on the test stand or on the dyno; I run it for 20 or 30 minutes. Then I dump it and run Valvoline Racing 10W30 after that. It's highly rated and has over 100,000-psi wear protection compared to around 64,000 or so for many of the other oils. It has some zinc in it—not as much as some others—but it has other additives that give it great wear protection."

Dan's Tip: Brad Penn 30W break-in oil works great for protecting the engines at startup, and Valvoline VR1 Racing Oil has superb psi wear protection.

Conclusion

So are you ready to spin that key, lay down some black marks, and let that Pontiac roar? There's no reason to put up with lackluster performance. Dan revealed his roadmap to real romp, step-by-step, with lots of specifics. There's no complex tricks or budget-busting hardware to buy, just some solid, dyno-proven basics and a bit of knowledge learned from experience to put your Pontiac out front.

SOURCE
Pure Stock Drags
http://www.purestockdrags.com