More tips for building a Pure Stock champ....

I said in the last post that I'd go in depth on building a Pure Stock contender. Since every engine line is different we'll have to concentrate on a specific motor. I've always been a Pontiac guy so I'll use a Pontiac as an example. I have also built many Chevys, Fords, Mopars and Oldsmobiles over the years, and if folks want advice on those I can certainly do posts about those engine lines. Anyhow-I'll use the Pontiac as our test mule. Since the 400 was used in virtually every model from 1967-78 these will be the most plentiful and chances are whether your running a LeMans, GTO, Firebird, Trans-Am or Gran Prix, this is the engine your car came with anyway. # 1. Bottom end. Most stock class rules say the engine has to be within 15 cubic inches of stock. Since a 400 Pontiac is actually 401 inches, you can build a 416. Eagle, Butler, Kauffman and other places offer Pontiac cranks in nodular Iron, cast steel and forged steel. They also offer various stroke lengths as well. Since Pontiacs are not high-revvers-were going to accentuate what the factory did, which is make big hp and torque at low rpm. Even though were technically building a race car-were going to redline it at 6,200 rpm for reliability. At that redline a stock crank or a cast steel one will work just fine. Well use one with a 3.79 inch stroke. This is slightly longer than stock which is 3.75. This coupled with a .030 or .040 overbore will give you 412-415 inches. Stock Pontiac rods are 6.675 inches. Eagle sells 6.8 inch rods for Pontiacs and Ross and TRW sell pistons to work with the longer rods. The extra stroke and longer rods will boost torque all through the range. This is why small-block Chevy NASCAR racers have used 6 inch rods for years. ( Stock is 5.7 ). Use a stock-type ( TRW, Melling ) replacement oil pump. # 2. Heads. Pontiacs run best with flat-top pistons and high-compression heads. If you have a 1970 or earlier engine with 72cc combustion chambers, your all set. this will give you about 10:1 on a 400. 1971 and later engines have much larger combustion chambers which dropped the compression. Any other time I would say use the Excellent Edelbrock Performer RPM heads with 72cc chambers. Most stock classes don't allow aluminum heads, you have to use iron. If you can't find some early heads-#670, 46,48 etc. the next best thing is the "6X" "smog" heads used on 350s and 400s from 1976-79. These actually breathe better than any factory head except the vaunted 1969-70 RAIV and '71-72 455HO heads. Pontiac heads can be milled as much as .060 inch to raise compression. ( You have to shave the intake side as well so the manifold will fit properly ). Using milled 6X's and flat tops will give you about 9.7:1 compression, which will be enough, because Pontiacs love a lot of timing. # 3. Cam. Most stock classes only stipulate that the cam has to be the original "type". In other words if the car had a hydraulic cam stock, then you have to run a hydraulic cam, you can't switch to a solid-lifter cam or a roller. However there's no real limits on lift or duration. I like one that Crane makes. It has 232 / 242 duration ( @.050 ) and .473 / .488 lift. It's a hair hotter than the factory RAIV ( 231 /240 and .470 ). It works great with a stick. If your running an automatic I like the Edelbrock Torker Cam. It has 224 / 234 duration ( @.050 ) and .465 / 488 lift. The slightly less duration gives it a better idle and allows it to work with a stock torque converter. Pontiacs make so much bottom-end torque that if you use a torque converter with more than 2,500 rpm stall speed, you'll just blow the tires off.  Since Pontiac heads ( exceptions are Edelbrocks or RAIV's ) don't breathe much over about .480 lift-you don't need a .600 lift cam. With a Pontiac, less is more. Either of these cams will pull hard from idle-5,800-6,200 rpm, which should be your shift point anyway. # 4. Induction. Most stock classes say the intake has to be the original type. With this rule-you could say your building an RAIV spec car. ( RAIV's and 455HO's had aluminum high-rise intakes from the factory ). If they allow this-Ames, NPD and other companies offer reproduction aluminum RAIV intakes. If the rules say the intake has to be Iron, don't despair. Pontiac Iron intakes from 1967-74 are excellent. ( 1975 and later models have the EGR valve intruding into the throttle opening which limits power above 4,000 rpm ). The preferred ones are the '67-72 models. ( No EGR valve at all ). Port-matching to the gasket helps. Carb-wise-Summit, Jet and other companies offer street / strip and race Quadrajets.  If your building a '62-63 Super Duty Catalina Tribute-they may allow an Edelbrock or Offenhauser dual-quad aluminum intake. If so-I'd use two 750 Edelbrocks. ( And a 4.00 inch stroke crank with 3.00 inch mains to get 434 inches with a .030 overbore on a 400 block. You'll be legal-within 15 inches of the stock 421 ). If your running a tri-power setup I'd use a mechanical linkage instead of vacuum. # 5. Exhaust. There are several companies that make ported and extrude-honed iron exhaust manifolds for Pontiacs. Behind them I'd use 3 inch pipes and low-restriction mufflers. # 6. Gearing. I'd use 4.10:1 or 4.33:1 gears. These ratios will allow you to rip out of the hole,and pull hard through all the gears. It's funny with a big-block-in my 455 Hurst / Olds when I swapped the 3.23 gears for 4.10s-it didn't help one iota in low gear. However it made a HUGE difference in 2nd and 3rd!!  Since were redlined at 6,200 rpm this will be perfect. You'll be going through the traps at 5,700-6,000. 4.88:1s would make you go slower, because you'd run out of rpm before the end of the 1/4. Depending on traction-this simple combination should run very low 12s or very high 11s, which would make you super-competitive. Maybe we'll do a small-block Chevy next.  Mastermind