There is a very large class of people that own 65/66 Mustangs that, as far as I can tell, anyway, have been, for the most part, ignored entirely. They don't really want that 100 pt. show car that is so nice and was soooo expensive that they're afraid to drive it, they also don't want to make their car capable of achieving warp factor three. They just want this car that they dearly love to be able to cruise around smoothly and reliably, without having it dump them out on the side of the road or have it start making weird noises or belching out big clouds of funky-smelling smoke. And I think, truth be told, that this is by far the largest class of Mustang owners. They take their car to some technician when what they actually need is a mechanic, and this, frequently, does not work out very well at all for the owner. They don't want to re-engineer the entire car, they just want someone to fix what broke. These are the people that I am trying help out with this blog. Some problems require a little bit of back and forth, as in, "Try this." "I tried that and it didn't change anything."
" Oh. well, you probably need to try that." " I tried that and it helped, but it still isn't quite right." "Now you need to try this...." If you go to http://www.allfordmustangs.com/ and then go to the classics forums, you will be able to do that with a pretty hefty gathering of some very knowledgeable people that also happen to be very friendly. None of that ridiculous one-upmanship, no flaming or abuse, none of that stuff. Just good, solid advice from people that know what they are talking about.

Tuesday, May 7, 2013

PCV system on a Mustang 1965 1966

Lately, I've had several people ask me about this system, how it works, what is it's purpose, etc...so, here's how that works and why it's important. As the fuel is burned in the combustion chambers of an internal combustion engine, the motor does not burn 100% of the fuel. Most of that unburnt fuel goes out the exhaust, but, some goes past the piston rings down into the crankcase. Also, all of the exhaust gases don't go out the exhaust. Some of that also gets past the piston rings, and again, ends up in the crankcase. As one might imagine, having these combustible gases hanging around in the oil pan can't be a good thing. What they actually do is contaminate the oil, degrade the lubricating qualities of the oil, and cause your motor to wear out a lot quicker than it should. That is with a motor in which everything is as it should be. In a motor that is getting a little tired and has excessive ring clearance, this problem is multiplied and the gases can accumulate quickly enough to actually catch on fire in the crankcase. People have devised different ways of dealing with this problem over the years, but, we'll stick to Ford's solutions. In the Model B Fords, the first cars that had the flathead V8s in them, the solution was very simple. Ford put a hole in the front of the oil pan up near the top and welded a flap in front of it to keep rocks and stuff from bouncing into the oil pan. A very straight-forward idea, but, one that cried out for some modifications. They later developed what was called a road draft tube, which you can find on some of the 64 1/2 Mustangs. This was the same idea, basically a hole to let air in through, but, a hole that road crud couldn't really find it's way through. However, dusty crud could still get sucked in.Next was the positive crankcase ventilation, or, PCV, system. Vacuum is generated by the pistons, so, they put a hose from the base of the carb over to one of the valve covers. The gases that blew by the pistons and wandered into the crankcase get sucked back into the combustion chambers. To solve the problem of the massive vacuum build-up this creates, they put a vented oil filler cap on a hole in the other valve cover. This allows fresh air to circulate through the motor and prevents the build up of the blow-by gases. They put a one-way valve on the hose that goes to the carb to prevent air/fuel mixture from going the wrong way.

A good and useful system, and very easily maintained. All one has to do is clean out the filter in the oilfiller cap to keep it from getting clogged up, and clean the PCV valve occasionally to keep it from getting stuck.


Dennis Ouellette said...

Nice description Veronica. That PVC system was considered the first of many pollution control devices. We've come a long way since the mid 60's.

Veronica said...

Thank you, Dennis. I was going to post a few pages from the January of 64 Shop Tips, which has some really cute pictures and diagrams of the new PCV system, but, it is such an amazingly simple system, based on an even simpler idea, that I figured all of that would just muddy up the water.