Here is a better-looking version...
Here is a better-looking version of a PCV valve from Summit Racing, part number 440308, that goes for $18.95, and is a great alternative to the less-attractive ACDelco model.
Q I recently read your story about relocating the battery to the trunk in your project Mustang. I was wondering how effective the body is for grounding the battery. Do you need to do anything special to make it work? I would like to do the same thing to my '68 Mustang.
A Mark, I'm happy to see you getting ideas from our latest project car, the Street Fighter Mustang. Keep this up, and we'll have some competition! Back to business; the battery ground cable goes to the rear frame section. The factory straight-six engine has a ground strap from the block to the frame connecting it ultimately to the battery's ground. Many electrical components use the engine to ground, so if this ground is bad, more than likely, many circuits will fail.
To determine if you need to add cables or straps to your car, you will need to perform a voltage-drop test. To do so, use a volt meter; you can purchase one at any hardware or auto parts store. Place one lead on each ground, and switch to read DC voltage. Since this test can only be performed under load, have a friend crank the engine while you read the meter. To give yourself a little more time, disconnect the ignition so the car won't start on you.
If the voltage drop across any connector, relay, switch, or ground is more than 0.4 volts, you have a problem. Ideally, it shouldn't drop more than 0.1 volts. If between the engine block and the battery's ground is over this 0.4-volt drop range, extending the ground cable closer to the engine can help.
Q Why is it important to use a PCV valve? What happens if you leave it out? Are there other ways to accomplish the same thing that a PCV valve does?
A First off, let's go over the purpose of a positive crankcase ventilation (PCV) valve. The engine compresses the air and fuel mixture in the combustion chamber, using gaskets, valve seals, and piston rings, to ensure that pressure is not lost. The seal is not perfect though, and it gets worse as the parts wear. This phenomenon is called blow-by. The pressure that squeezes past the seals builds up in the crankcase and can leak out other parts of the engine. In the '20s, before emission laws, it was acceptable to allow this high hydrocarbon content vapor to leak into the atmosphere. Of course, this didn't last long, and the crankcase fumes were redirected into the engine using a PCV valve. It's usually located at the top of the engine's valve cover. It's a one-way valve that allows the blow-by gases to be drawn back into the intake while not letting the intake breathe into the valve cover. This traditional setup can be upgraded with better-looking valves, but it hasn't fundamentally changed. The down side to using a PCV valve is that along with the fuel-rich blow-by gases, oil vapors are trapped in the same spaces. This means that they both get sent back into the engine to be consumed with the regular air and fuel mixture. The oil can leave residue on the back of the valves and in the combustion chamber, inhibiting flow, and generally being dirty. Many engine builders use a catch can without a valve to allow free exchange of gases to the crankcase. These catch cans aren't as environmentally friendly, since the vapors are still released into the air, but they help keep the engine clean.
Here's Steve Schalk's big-block...
Here's Steve Schalk's big-block Chevy in his '66 Nova, featured as an "Under Construction" car in our February '09 issue. He used a Summers Brother's distributor drive kit to relocate his spark stick from the back to the front.
Another option is to use PCV valves, but re-introduce the crankcase vapors into the exhaust, that way, the engine is not effected by the oil contamination. It's also common for builders to incorporate a vacuum pump. This literally pulls the blow-by gases out, and increases the pressure differential between the combustion chamber and the crankcase-the result being more horsepower to the wheels.
Q I have a question concerning the article titled "Incorrect Nova" in your "Under Construction" section for the February '09 issue. Mr. Schalk's Nova is certainly going to be a head turner. In the photo with the engine mocked up in the bay, there is a distributor in the front of the engine. I thought I knew all the latest trends and aftermarket products, but this is either something that I have missed, or this was done to see if the readers are really paying attention. What's the deal?
A Bud, great question! I didn't notice the distributor placement until I got your letter. I gave Mr. Schalk a call to clarify. He told us this is a kit from Summer's Brothers Racing. It's to relocate the rear-mounted distributor on small- and big-block Chevys to the front. This gives much more clearance for superchargers and fuel injection setups. This is how Steve Schalk fit his one-off Morrison Motorsports fuel-injection setup atop his 572.
The kit comes with everything you need to change over to this front-mount system. It includes all the spacers, hardware, timing cover, and gearing. Most water pumps will still work with this change, but the location of the alternator my need to be changed. The kit goes for $678 for a big-block, and $620 for small-block, a fair price for a some extra room or a unique look.
Summers Brothers Racing
We're Waiting To Hear From You!
Letters will be printed as space permits, and may be edited for content and clarity. Send material to: Popular Hot Rodding Tech Mailbox, 774 S. Placentia Ave., Placentia, CA 92870. Or send your thoughts and comments to us at the following email address: email@example.com. Emailed questions may be answered electronically, as well as possibly published in PHR. Popular Hot Rodding and Source Interlink assume no responsibility for errors in publication.