Performance Q&A Tech Section

Our Resident tech guru, Big Mac, tells all.

Kevin McClelland Apr 1, 2009 0 Comment(s)

I'm running a Streetmaster single-plane due to height clearance issues. I understand this is a single-plane manifold, which should provide the best of both single- and dual-plane worlds (up to 5,000 rpm). The engine pulls very strong with the stock cam. Do you feel this would be a much stronger engine with a dual-plane like the new Weiand Street Warrior dual-plane, or a Performer RPM? I would have to do mods to the engine cover to make an RPM fit. I'm looking forward to your reply.
Rich Chrzanowski
Via e-mail

A Don't you like to use Sawzalls? That's one of the best tools ever invented. Steel, wood, plaster-nothing gets in its way! Yes, I spent five years working in the R&D department at Edelbrock in the early '80s. The Streetmaster line of inlet manifolds had been out for several years when I got there to address the emissions performance market. Applying the knowledge found from racing single-plane manifolds and downsizing them into appropriate street manifolds was the goal. It worked very well for the day, and then we moved on to the Torquer II line of street-performance manifolds. The Torquer II manifold has a larger cross-sectional runner and improved runner designs over the Streetmaster and will give you better upstairs performance.

The current design of street-performance dual-plane manifolds will outperform these early single-plane designs, especially in a marine application, where you need the most torque to get the boat out of the water right at torque peak. With a performance dual-plane, you should experience a good 20 lb-ft gain over the single-plane design.

I really like your combination of parts. The iron Vortec oval-ports are very nice castings with the inlet port from the early cast-iron oval-port heads. The differences from the early heads are a raised exhaust port with a nice short-side radius turn, and a kidney-shaped combustion chamber. These heads work very well stock and, with the port work, will run much better than any GM oval-port. The camshaft you have selected will give you great torque and run out of steam right around your target; with the "water manifold" you have to run on the exhaust side. As for the manifold, we recommend getting out the Sawzall. The gains in part-throttle performance and torque peak will be worth the mods. This will round out your package of the Stage II upgrades. Retain your Q-jet and run a PN 7164 Performer RPM.

We'll assume you have this engine in some type of pleasure boat for skiing. Make sure your skiers are warned of your new found torque, and have fun!

Dot What?
I have an interesting problem with a brake system on a '37 Chevy street rod. When the brakes are lightly applied, as in a parking lot (1-2 mph), the pedal goes to the floor, only intermittently. It may happen twice a day or only once a month. I have replaced the (7-inch dual diaphragm) booster twice and the master cylinder (1 1/8-inch-bore '79 Corvette) six times, the last three times with brand-new AC Delco parts (started with remanufactured). I am using DOT 4 fluid. I was told DOT 5 will cause this, so I flushed the system and have had DOT 4 in it for four master cylinders and one booster. I'm also using four-wheel disc brakes (GM calipers) and 2-pound residual valves, one front and one rear. I have an adjustable brake bias valve in the rear only. The brake pedal has never gone to the floor while driving above 2 mph. My engine is a 260-horse GM crate with 19 inches of vacuum in gear at idle with the vacuum advance disconnected. The system is well sealed with no leaks anywhere, and the pedal is firm except when it's headed for the floor. I am an ASE-certified master mechanic who is going bald trying to solve this problem. Help!Henry JamesVia e-mail


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