When it comes to pumping iron, Randy Brzezinskihad few equals. As a matter of fact, he does it his very own way, by letting iron heads and manifolds do some extended aerobics. If you are running Hobby Stock, Limited Late Model, or Sportsman, you couldn’t miss hearing about Brzezinski because he is a prime exponent of having the stock cast-iron intakes and heads pull more air than ever before. He has learned all the good part numbers and the ways to make them respond. One of Brzezinski’s findings is that the EGR-type Q-Jet intake manifold produces more power and is cleaner internally than the early non-emissions manifold in stock form. Unfortunately, EGR manifolds don’t lend themselves to modifications, and the early ones are the only ones worked on. The first thing you hear coming into Brzezinski’s shop is a big mill cutting on one of those Q-Jet manifolds opening up the plenum. By the time the operation is done, the individual bores are gone and there are two fully opened oval-shaped plenum areas. Also, the center divider is not only much thinner, but it’s also been brought down 1/2-inch.A Q-Jet manifold can become quite effective. It is a good sound design and responds to some internal work. To get to the inside runners, Brzezinski does no sectioning or welding; instead, he bores out two large openings on the bottom and two more on top. This level of modification is called “Fully Modified”. This allows full access to the intersection of the main runner with the intake port runners. Rounding off the inside corners helps improve the flow and keeps fuel from separating. The access port also allows greater freedom in reworking the manifold roof and runners.After the internal shaping is done, a round, two-piece cover with a formed lip is set into the counter-bored opening. An epoxy coating plus three retainer screws reseal the manifold. You can still get in there to change manifold cc’s, though there is not real reason to do so. The main problems Brzezinski addresses in a Q-Jet manifold relate to evening out airflow and fuel distribution. Normally, the inside runners, 3-5 and 4-6, tend to run lean. He helps control wet fuel flow with plates along the floor that redirect it, as well as airflow improvements to bring more fuel in the right directions.Holley-Chevy ManifoldThe 327 small-block was offered with a GM manifold drilled for the Holley standard flange carburetor pattern. It has two-barrel intake sizes and a four-barrel intake runner sizes and a four-barrel plenum; also, the main feed runners are slightly smaller on the standard flange manifold than on the Q-Jet manifold. While the standard flange GM manifold puts or a little less power than the Q-Jet one, it is a good piece and makes more torque, especially with a smaller motor. It is not available new and is tough to come by used.2 Barrel Chevy ManifoldAlso available is a two-barrel manifold specified in a number of classes. Brzezinski re-bores the down runners from the carburetor to the intake plenum area, opening them up from 1.710- to 1.750-inch, and mills them at a slight angle to favor the front cylinders. This manifold, just like the Q-Jet, receives access ports, and now the square foundry edges inside the casting can be blended into smooth curves.
All of Brzezinski’s manifolds start out with hot tanking, glass beading, and flow testing. Any threads that need to be repairs are helicoiled. The tin heat shield, riveted at the exhaust crossover, is removed and discarded.
Brzezinski reworks the new shield, spot welds extensions, and bolts in the new full-length assembly. The extended shield keeps hot oil away form the entire bottom of the manifold, helping to keep it cool. It also protects the epoxy on the access plugs against oil wash.
Brzezinski has selected Fel-Pro gaskets and used their numbering system to match the ports of the head and intake manifold. The 1204 is used mostly for stock heads. A 1205 is reserved for an extensively ported straight plug head or a cleaned-up bow-tie. If class rules allow going 1/2-inch into the head and manifold, enough material can be removed to eliminate any overhang.
All of the port openings on the head and on the intake manifold are machined on a mill to template size, which saves a lot of work. The same template is used for both intakes and heads but had two built-in sizes, forming small steps. The cylinder head side is .050-inch taller than the intake and .035-inch wider.
Brzezinski makes a 1-inch-thick two-barrel Rochester spacer, which picks up a couple of horsepower. It the rules allow a 500-cfm Holley, you can add an additional 20 to 25 horsepower. Here the 108 adapter couples the 500 Holley to a two-barrel GM manifold. The SuperFlow dyno consistently proves that this adapter works better with a 1-inch thickness than 2-inches.
To wring the most horsepower from a given engine, you many want to look into the two-piece 101 and 105 adapters. Slots in their sliding base allow the carburetor to be moved forward or back for improved fuel distribution. Begin with the adapter way forward, then tune. In its various combinations, a 101 will fit a Q-Jet manifold or a Victor Jr.
Another very useful adapter for two-barrels is the 2-inch-tall 114. It slides forward or back just like the 101 and 105 but has rounded outlets to blend with the manifold roof.
There is a wide range of adapters which work with a Q-Jet manifold. A 104 mates it to a 700-, 750-, or 800-cfm Double Pumper. These adapters are retained with recessed Allen bolts and have a larger outboard Holley bolt hole pattern fitted with helicoil inserts.
Brzezinski explains that a 180° manifold doesn’t like as much spacer height as a single-plane open manifold; in fact, it suffers from a schizophrenic personality because the upper runners like a spacer while the lower ones do not. A 1-inch spacer with individual holes is the best compromise. You can combine the Q-Jet four-barrel manifold and either Rochester or Holley two-barrels to good advantage. One saving grace is that the Q-Jet manifold and carburetor go together without and spacers. GM must have done its homework.