Gang,
Whats a good source for learning the names of LT1 engine components?

I've googled, "LT1 engine" and couldn't find anything that named the components.

I'm thinking of a diagram showing the components, and it would be great if there was an explanation of what they do, too.

The reason I ask is I'm still new and wanting to learn the LT1 and when people mention a component and that they are having a problem with it, I'll know what they mean.

Case in point, I read something about a "Plenum". Couldn't tell ya what that is or where it's located, much less what it does.

 

a decent manual is best, the factory ones rock

Here's a page on rebuilding them, not much of the EFI is covered.
http://www.automotiverebuilder.com/ar/ar99928.htm
There's several books coving just the EFI.

 

Excellent advice, but don't feel like the "Lone Ranger" for not knowing this stuff. We all had to learn this.

As you may already know, GM LOVES to change things.

A plenum is part of the intake manifold. In most cases the plenum is built into the intake manifold and not individually serviced. When the TPI (Tuned Port Injection) engine was first installed in the Vette, the plenum became a separate part.

So you'd have a separate, stand-alone plenum and two sets of runners; four runners on each side of the engine. Air would enter the air filter housing, then through a MAF (Mass air Flow Sensor), then through a flexible connector and into the TB (Throttle Body). THEN into the plenum. From there the air would travel through the eight runners, into the intake ports on the cylinder heads and finally into the cylinder bores.

As the air enters the cylinder head, fuel is "injected" into the air flow and the mixture of air and fuel (at a ratio that varies depending on lots of different variables, but in a fully warmed up and properly operating engine the target ratio is 14.7 parts of air to every one part of fuel).

So, for your LT1, pop the hood, stand on either side of the engine. Reach over until your hand is directly over the center of the engine. Now drop your hand down until it touches the engine - that's the plenum. However, on the LT1, the plenum and runners are a single unit, not three seperate pieces as with the L98 engine.

Engines that run carbs also have intake manifolds that have intergal plenums. The carb sits on the plenum and the carb bolts to it.

The actual size of the plenum can be adjusted with different thickness spacer plates. These plates, installed between the base of the carb and the manifold's plenum. may (or may not) help engine power.

Hope this makes sense and helps.

Jake

 

If you want to learn all about the LT1/LT4 engines....get the "How to Rebuild Your LT1/LT4" book....about $20 from many places....Amazon, ebay, etc.

 

It's a staple in my garage. There are a few inacurracies in it but nothing that will cause problems if doing major work on one. And it's generally much easier and quicker to find the occasional spec in when needed, compared to the FSM. But don't get me wrong, the FSM is indispensible too.

 

Great info, guys!
Thanks!
cc

 

The Haynes manual helped me out a lot...for changing brake pads and simple stuff so far. A lot of people here recommend the shop manual...which is pricey, but probably worth it.

 

Since you want to know what some of them do, here's what some of them do:

MAF (Mass Air Flow Sensor): It has very thin wires inside that receive voltage readings from the ECM/PCM (the computer). This voltage heats the wires. As air flows over the wires, the wires cool and the computer senses how much cooling takes place. Based on that, the computer adjusts the timing and fuel. There are more specifics on this, but that's the jist of it.

IAC (IDLE AIR Control) Idle speed is programmed into the computer and it changes the idle speed of the engine based on input from various sensors that keep feeding the computer information. It's actually a little motor with a pintel (a little tip) that moves in and out to control the idle speed thereby allowing less or more air into the throttle body.

TPS (Throttle Position Sensor) This one tells the computer how much/hard you're depressing on the accelerator pedal. Based on what it sends to the computer, the computer adjusts fuel and ignition timing to compensate. It's about voltage.

There are tables programmed into and used by the computer when it responds to all these inputs from the sensors. All this happens really fast.

Then you have sensors that tell the computer about temperatures. Air temperature sensor and coolant temperature. One tells the computer the temperature of the air entering the engine, still another tells the computer the temperature of the coolant. Based on these, the computer adjusts timing, idle speed and fuel (injector "on" time).

Then, there is a timer that tell the computer how long the engine has run from start up. The system will go into different "modes" based on how long the engine has run. For example, the engine is what is referred to as "Open Loop" when it's first started. After a short period of time, I'd say less than 2 minutes, the system goes into a different mode - Closed Loop - IF ALL ELSE IS WELL.

Then there is the O2 sensor(s) installed in the exhaust system that send(s) feed-back data to the computer of the exhaust gas leaving the engine. Some engines have only one 02 sensor, other has as many as four.

There are more, lots of sensors/senders that the computer relies on.

Best I can do on short-notice. LOL

Hope it helps.

Jake

 

At least you want to learn, that's the first step. Get the factory service manual and the how to rebuild your LT1/LT4 book. You can learn quite a bit in C4 tech. Read the threads and when you don't know what something is in one of the threads google it.

 

The Haynes book gives you nice pictures of things like brakes, shocks and simple R & R procedures. The FSM gives detailed trouble shooting flow charts for every system on the car. The FSM calls out all the factory tools, though few of us can get our hands on all of them. The FSM also gives system logic, how they interact with each other.