C4 Cam Swap

Welcome to My C4 TPI Cam Swap How To

Small block Chevy's do not make the cam a priority in their oiling system. That means the cam must rely upon oil flung from other parts of the engine for its lubrication. Small block Chevy cams take a long time to break-in, and then, they are more likely to wear out. By 100K miles, you can bet your cam has seen better days.

In my case, my wife's C4's cam was probably okay, even though it had over 106K miles on it. The car was very well cared for. As part of a 100K service, among a lot of other items, I swapped out the valve seals, pushrods, and due to some bad advice, the valve springs.

New valve springs, if not accompanied by a new cam and lifters, will wipe out the lifters in short order. The increased pressure from the new springs places too much stress on the old lifters. So they crap out.

And this is exactly what happened. After thirty short miles, the car's idle began to hunt, and the car wanted to stall. Luckily, I was close to home, so I pulled the valve covers and found that I could not remove the lash from the number four cylinder. The lifter was toast.

So follow along as I swap out the cam. If you are unfamiliar with TPI and plan on doing any above the manifold work, this pictorial should prove invaluable to you.

Before we start, make sure you have, at minimum, a weekend to work on the car. Also, a nice, heated, and well lit garage helps.

Tools:

Breaker bar
Metric and SAE socket set
Full set of Torx bits
1/4 inch drive
3/8 inch drive
1/2 inch drive
Small socket extension
Medium socket extension
Flat blade screwdriver
Floor Jack
Jack Stands (sturdy)
Bucket
Zip Lock Bags
Sharpie Marker
100 Nitrile Gloves (greasy hands suck)
Safety Goggles
Adjustable Halogen Lamp

Cam and lifter set (Duh!)
Timing set
Water Pump
New serpentine belt
TPI intake gasket set (for the intake and runners as well)
Thermostat
Upper Radiator Hose
Coolant
Distilled Water

Of the above parts, only the gasket set and cam and lifter set are mandatory. The rest only need to be replaced if you feel it is time. If the service life on any of the above are questionable, do the job now, while your car is apart.

Before we get started, there are a few things you need to do:

1. Relieve the pressure in the fuel system. Do this by removing the fuel pump fuse and then start the car. When the car dies, the fuel pressure is relieved.

2. Remove all the spark plugs.

3. Loosen, don't remove, the nuts on top of the rockers.

4. Drain the cooling system.

If you know how to put the engine at TDC, why are you even bothering with this How To? Never mind. Go ahead and put the engine at TDC. If you don't know, you're in the right place. We'll cover it later.

Here is a shot of the passenger side of my TPI. The valve cover has already been removed, so has the PCV valve and tube. Removing these items is easy. The cover comes off with four bolts. And the tube simply pulls out. The tube goes back in, roughly as you see it lying on the plenum. But it would rotate forward, towards us. I mention this now, because these are the sort of details that may seem clear, while it's in front of us. But at the end of the job, when we are eager to put it all back together, the details are anything but clear. And that can really stink.

This is the front TPI vacuum hose routing. I've included, in this shot, where the PCV pipe goes. Again, these are details that will be important when we go to put this back together. This next photo is of the rear TPI vacuum routing.

Now let's remove the runners. They are Torx fasteners, and I believe they take a T-40 socket. If you've never removed these before, your car's bolts might be a bear to remove.

Don't try to use a set of cheap bits. They'll wrap around themselves and break. Go to Sears or flag down your local Snap-On guy. You'll most likely break these sockets as well. But at least you can keep returning the broken sockets until the fasteners are all removed. When we put the fasteners back in, we'll spray some anti-seize on them.

Those Torx fasteners in your hand? Put them in a Zip Lock Bag! And then mark the bag. You wanna lose this stuff? Do you? Do you? Do YOU?! Go ahead, hit me. Sorry. I'm watching Raging Bull right now, and I'm getting carried away. But that's not for you to worry about. But those fasteners, all of them, are something to worry about. So put the right side runner fasteners in a bag, and write down what they are. Then, put the bag in a safe place, like a sturdy box. Go ahead, hit me.

Let's also get rid of the distributor cover. This requires removing 3 very small Torx fasteners. Take a look at the picture above. I'm not sure of the actual size, but I can tell you it's one of the smallest. But you already knew that.

Here's the distributor. Let's pull those spark plug wires off. But do yourself a favor. If your wires aren't already numbered, take that Sharpie, and mark each wire with the correct plug number. This will make it easier when we go to put it all back together.

Here is the front of the throttle body, and the rear of the snorkel that attaches the Map sensor. Take a flat blade screwdriver and loosen the hose clamp.

Here is a clip that holds the MAP sensor tight to the air intake. There are two of these clips. Be gentle. Just to the left of my finger, you'll see another hose clamp. Go ahead and loosen this as well. Then, we'll remove the MAP sensor.

The MAP sensor is very, very delicate. Don't just place it anywhere. Put it someplace you know will be safe. If it drops, you're out a whole lotta cash.

Unplug the wire that goes to the MAP. You can see it just below. There is a clip that holds it in. Then remove the assembly.

Here is the front of the MAP sensor. The screen and the wire behind it, are fragile. Be careful. Some people like to remove the screen from their MAP. They say they achieve more power from this. I left mine. But if you want to remove yours, now is a good time to do it.

Unplug this electrical connector. It goes to the throttle body. You may want to wrap it in masking tape and write something like "goes to throttle body" on it. I didn't. But if you feel you need to, I swear I won't laugh.

Here, we begin the removal of the throttle bracket. This bracket holds the throttle cable to the plenum. There are other fasteners in the front of the bracket that also need to be removed. You'll figure it out.

This wire loom clip pops right out.

Now let's remove the throttle body fasteners. There are four of them. They are pretty long. Make sure you don't lose any of them. Are you gonna bag them? Of course you will.

Goto Page 2

	Go Back Home Welcome to My C4 TPI Cam Swap How To
	Small block Chevy's do not make the cam a priority in their oiling system. That means the cam must rely upon oil flung from other parts of the engine for its lubrication. Small block Chevy cams take a long time to break-in, and then, they are more likely to wear out. By 100K miles, you can bet your cam has seen better days. In my case, my wife's C4's cam was probably okay, even though it had over 106K miles on it. The car was very well cared for. As part of a 100K service, among a lot of other items, I swapped out the valve seals, pushrods, and due to some bad advice, the valve springs. New valve springs, if not accompanied by a new cam and lifters, will wipe out the lifters in short order. The increased pressure from the new springs places too much stress on the old lifters. So they crap out. And this is exactly what happened. After thirty short miles, the car's idle began to hunt, and the car wanted to stall. Luckily, I was close to home, so I pulled the valve covers and found that I could not remove the lash from the number four cylinder. The lifter was toast. So follow along as I swap out the cam. If you are unfamiliar with TPI and plan on doing any above the manifold work, this pictorial should prove invaluable to you. Before we start, make sure you have, at minimum, a weekend to work on the car. Also, a nice, heated, and well lit garage helps. Tools: Breaker bar Metric and SAE socket set Full set of Torx bits 1/4 inch drive 3/8 inch drive 1/2 inch drive Small socket extension Medium socket extension Flat blade screwdriver Floor Jack Jack Stands (sturdy) Bucket Zip Lock Bags Sharpie Marker 100 Nitrile Gloves (greasy hands suck) Safety Goggles Adjustable Halogen Lamp Cam and lifter set (Duh!) Timing set Water Pump New serpentine belt TPI intake gasket set (for the intake and runners as well) Thermostat Upper Radiator Hose Coolant Distilled Water Of the above parts, only the gasket set and cam and lifter set are mandatory. The rest only need to be replaced if you feel it is time. If the service life on any of the above are questionable, do the job now, while your car is apart. Before we get started, there are a few things you need to do: 1. Relieve the pressure in the fuel system. Do this by removing the fuel pump fuse and then start the car. When the car dies, the fuel pressure is relieved. 2. Remove all the spark plugs. 3. Loosen, don't remove, the nuts on top of the rockers. 4. Drain the cooling system. If you know how to put the engine at TDC, why are you even bothering with this How To? Never mind. Go ahead and put the engine at TDC. If you don't know, you're in the right place. We'll cover it later. Here is a shot of the passenger side of my TPI. The valve cover has already been removed, so has the PCV valve and tube. Removing these items is easy. The cover comes off with four bolts. And the tube simply pulls out. The tube goes back in, roughly as you see it lying on the plenum. But it would rotate forward, towards us. I mention this now, because these are the sort of details that may seem clear, while it's in front of us. But at the end of the job, when we are eager to put it all back together, the details are anything but clear. And that can really stink. This is the front TPI vacuum hose routing. I've included, in this shot, where the PCV pipe goes. Again, these are details that will be important when we go to put this back together. This next photo is of the rear TPI vacuum routing. Now let's remove the runners. They are Torx fasteners, and I believe they take a T-40 socket. If you've never removed these before, your car's bolts might be a bear to remove. Don't try to use a set of cheap bits. They'll wrap around themselves and break. Go to Sears or flag down your local Snap-On guy. You'll most likely break these sockets as well. But at least you can keep returning the broken sockets until the fasteners are all removed. When we put the fasteners back in, we'll spray some anti-seize on them. Those Torx fasteners in your hand? Put them in a Zip Lock Bag! And then mark the bag. You wanna lose this stuff? Do you? Do you? Do YOU?! Go ahead, hit me. Sorry. I'm watching Raging Bull right now, and I'm getting carried away. But that's not for you to worry about. But those fasteners, all of them, are something to worry about. So put the right side runner fasteners in a bag, and write down what they are. Then, put the bag in a safe place, like a sturdy box. Go ahead, hit me. Let's also get rid of the distributor cover. This requires removing 3 very small Torx fasteners. Take a look at the picture above. I'm not sure of the actual size, but I can tell you it's one of the smallest. But you already knew that. Here's the distributor. Let's pull those spark plug wires off. But do yourself a favor. If your wires aren't already numbered, take that Sharpie, and mark each wire with the correct plug number. This will make it easier when we go to put it all back together. Here is the front of the throttle body, and the rear of the snorkel that attaches the Map sensor. Take a flat blade screwdriver and loosen the hose clamp. Here is a clip that holds the MAP sensor tight to the air intake. There are two of these clips. Be gentle. Just to the left of my finger, you'll see another hose clamp. Go ahead and loosen this as well. Then, we'll remove the MAP sensor. The MAP sensor is very, very delicate. Don't just place it anywhere. Put it someplace you know will be safe. If it drops, you're out a whole lotta cash. Unplug the wire that goes to the MAP. You can see it just below. There is a clip that holds it in. Then remove the assembly. Here is the front of the MAP sensor. The screen and the wire behind it, are fragile. Be careful. Some people like to remove the screen from their MAP. They say they achieve more power from this. I left mine. But if you want to remove yours, now is a good time to do it. Unplug this electrical connector. It goes to the throttle body. You may want to wrap it in masking tape and write something like "goes to throttle body" on it. I didn't. But if you feel you need to, I swear I won't laugh. Here, we begin the removal of the throttle bracket. This bracket holds the throttle cable to the plenum. There are other fasteners in the front of the bracket that also need to be removed. You'll figure it out. This wire loom clip pops right out. Now let's remove the throttle body fasteners. There are four of them. They are pretty long. Make sure you don't lose any of them. Are you gonna bag them? Of course you will. Goto Page 2