We're not aware of a template for this, but the factory assembly manual should list specs to check the squareness of the chassis. These are distances to be measured from specific points on the chassis, usually in an X configuration. So, for example, if you had a complete chassis and were to measure from a prescribed point at the rear of the passenger-side lower control arm to another specific point just ahead of the axle on the driver side, and then did the same for the opposite points, both values should be the same. If not, something is probably tweaked somewhere. On the early F-cars and X-cars with bolt-on subframes, there should be a spec to measure across the subframe mounting points. You could probably use these specs to measure from the rear subframe mounts-which you indicate are still intact-to determine where the fronts should be. Assembly manuals for these cars are available as reprints from restoration supply sources like Classic Industries (800/854-1280, www.classicindustries.com).
Head GamesI am a new subscriber to your magazine and find your articles very informative to a young motorhead like myself. In the Aug. '04 issue you go over the 500hp heros, and that's where my question comes in. Two of the seven blocks have aluminum heads. The only iron heads were on the Chevy 454 and the Cadillac 500ci. What is special about aluminum heads if you can achieve 500-plus horsepower with the stock cast iron? Is there a reason to spend $500 and up on a set of heads?A.C. McMullenSergeant, US Marine CorpsChesapeake, VA
The power that aluminum heads help an engine generate does not come from the material itself. Aluminum is used in making cylinder heads primarily to save weight, and these savings can be significant when dealing with big-blocks. Aluminum is also easier to work with, either when it comes time for porting or if welding has been necessitated by damage. Since the technology is now readily available to produce durable aluminum heads that will seal effectively to cast-iron engine blocks, aftermarket parts manufacturers will usually opt to go this route and take the weight savings.
The powerful engines you saw that used "stock" iron heads were not really stock. The castings had been expertly ported to increase the airflow capacity, thus enabling the engines they're on to make more power. Many factory castings can be reworked to significantly increase airflow, but this takes skill and time-just hogging out the ports won't necessarily do it and might make it worse. For years, this was the only way to prepare engines for extreme performance, but as the aftermarket continues to develop new heads utilizing modern port and chamber technology, the need for custom-ported stock heads diminishes, at least when you're dealing with 500hp street/strip engines. The art of cylinder-head porting is still evolving, though the results are usually aimed at making much bigger power numbers than our story was intended for.
| | Pure | 50/50 | 70/30 |
| Water | Antifreeze/Water | Antifreeze/Water |
| Freezing point | 0C/32F | -37C/-35F | -55C/-67F |
| Boiling point | 100C/212F | 106C/223F | 113C/235F |