I Blew It Up!
Q I've seen quite a few articles on the 400s lately in your magazine. I happen to have a 406 in my '89 fullsize Blazer (lifted and such with 36s). My engine is a '76 400 small-block bored 0.030 inch over. Not sure of the cam specs, stock/ mild. I have my 350 '89 TBI setup and heads (steam holes drilled), intake, and harness. I don't have a chip or different injectors on it; it's all stock. I've had quite a few people tell me I'm going to blow engine up because it's running lean. They also say it will never work with the setup I have. Of course they've never seen my truck, and they're all "expert engine builders." The engine was originally built and stuck in my buddy's van three years ago and I put it in my Blazer two years ago.
Can you put a stock 350 TBI setup on a stock 400/406 and have it perform without reprogramming the computer? For the dollar-conscious, would that be reasonable low-buck build? I tow my boat to the lake (120 miles away) and average 16 mpg driving 65-70 mph. I thought this was OK, but with all these people on an online forum telling me I'm going to toast the engine, I thought I'd get an expert opinion. Also, if I did want to upgrade my setup, what would be some good choices? I'd like to keep it a reasonable street engine and keep the TBI. Thanks for any input.ShawnVia e-mail
A How does it work on yours, but everyone else's melts down? All the people telling you "You're gonna blow it up" are not wrong. Why doesn't your engine burn up? That's a really tough question. Let's take a look at some of the facts.
Going from 350 to 400 cid is an increase in displacement of about 14 percent. Working nothing else into the equation, you should be flowing 14 percent more air with the larger displacement. To properly fuel the engine, you should also need approximately 4 percent more fuel. The fuel injection system on your Blazer is what is called a speed density system. The factory creates an airflow model on the engine dyno called the volumetric effi ciency table. This is programmed into the computer and based on the displacement of the engine, it fuels the engine to a pre programmed air/fuel ratio. The computer has the ability to learn when the O2 sensor sees air/fuel ratios that are out of the boundary of the calibration. Can the O2 move the fuel 14 percent? No, it shouldn't have the room to move the fueling that far; however, your truck has lived a lucky life, and you have more than two years on it, towing and everything.
We would contact GMCOPO's Tom Woodside; he worked with GM when developing the HT502 TBI engine package for GMPP. He has tremendous experience working with GM TBI systems both on small- and big-blocks. He can adjust the displacement in your calibration to your new 406 cid. This will give the computer the room to go either leaner or richer based on operating condition.
Based on the fact that you've been knocking down very good mileage numbers, and that you're happy with your current performance, we wouldn't make big changes. Upgraded exhaust and air-intake system, and getting the calibration right would be our recommendations.
Source
gmcopo.com
Don't Get Cranky
Q I purchased a CVR Protorque mini starter, PN 5323OS, for an '84 Camaro with 355ci small-block. My problem is how to wire it. There is no terminal for the start wire from the ignition, only a positive from the battery and a ground. Do I need a remote starter solenoid? Thanks.Dave CaslerVia e-mail
A It took some digging, but I found your starter. Sold by CVR Automotive, it's a Nippondenso Gear Reduction unit that produces 1.9 hp, weighs 10 pounds, and has a 4:1 gear reduction, which is very similar to what was used in the late-'80s Corvettes.
As for the wiring, the photos I found showed a positive battery terminal with a 13mm nut, and next to it is a blade spade con nector to attach your start wire from the ignition switch.
Source
cvrproducts.com