Mazda Laguna Seca Raceway & Chevy Tech Help - Performance Q&A

Kevin McClelland Nov 1, 2008 0 Comment(s)

For ultimate power, we'd recommend an 850- to 950-cfm carb. This is a perfect match if you have a 5,000-stall speed or manual trans behind your little 383 hottie. Also, you will need 4.56:1 to 4.88:1 rear gears. The higher the stall and lower the rear gears, the larger the carburetor can be. For drag racing (accelerating engines) you need a carburetor with enough head room (cfm) to allow the engine to accelerate without creating a restriction. Any time you create vacuum in the inlet manifold below the carburetor, you reduce the air density, which reduces power. If you don't have all the combination to support the larger carburetor, you must Band-Aid the situation with a lower-cfm carb. This will allow the engine to accelerate from a lower rpm without driveability issues. If your Camaro is a true race car, this shouldn't be an issue. If you need a smaller carb for your application, choose between 750 and 850 cfm. This will give the intake system the velocity to create a proper fuel curve at slower engine speeds.

Check with your manufacturer of choice for its recommendation. Either Demon or Holley can sell you an over-the-counter carb that will give you what you need. Good luck with your bracket project and see ya at the races.

Sources:
barrygrant.com
holley.com

LT1 Imposter
Q
What are the differences, if any, between the LT1 swap engines that were put in the '96 Buick Estate wagons and the ones put into the Corvettes? I currently have a wagon that has the swap in it, but I would eventually like to start building a more performance-oriented vehicle. Any advice would be much appreciated.
Trevor Schipper
Kalamazoo, MI

A The LT1 engine was first placed in the '92 Corvette, then released in Camaro and Firebirds in '93 with the introduction of the fourth-gen F-bodies. In '94 the LT1s found their way into the B-body line (Impala, Caprice, Caprice wagon, Buick Roadmaster and Roadmaster wagon, and Cadillac Fleetwood). What many don't know is that GM also released the L99, a visual duplicate to the LT1, except that it only displaces 265 cid! Just think, you get this thing home from the wrecking yard with your prized LT1 only to find out it's a 265. Luckily, if you check on the left side of the rear of the block, just in front of the bellhousing mounting surface, it has either 5.7L or 4.3L cast right into the block. Something to look for!

There are many similarities between the LT1 B- and Y-car engines. The main differences are the cylinder heads. The LT1 iron heads were designed after the aluminum heads were released. Truth be told, the iron heads run better than the aluminum LT1 heads except for the fact that they weigh more, and since they're cast iron, you can't run as much compression. The differences in the blocks are that the Corvette LT1 block has four-bolt mains. The camshaft is slightly more aggressive, if you want to call the Corvette camshaft aggressive. The bottom line is that the B-car LT1 is a great building block for a performance engine. As long as you keep engine speed to a reasonable level and don't run the engine in a boosted condition, you will be fine with two-bolt mains.

Keep your eyes out for those pesky L99 Mouse motors. Any of the other Gen II small-blocks are great cores for performance buildups.

Transcripts
Q
I need some help decoding the transmission I purchased used from the local auto recycling yard. The salesman said it came out of a '92 IROC-Z Camaro. I have talked to Chevrolet parts men and dealership mechanics, including transmission rebuilders, and I keep getting the runaround. All I know is that the transmission is a TH700-R4 automatic MD8-MXO overdrive. I also purchased a catalog that has '67-93 Camaro ID numbers. So here is what I have: 2DDM 164 1 H. What is this transmission from, and out of what vehicle and model?
Richard J. Placek
Via e-mail

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