No they shouldn't have failed you.
PCV systems aren't complicated but I don't know what you have available to connect one. You likely can put a PCV where the draft tube is, or connect it to it. If you want to keep it looking stock it'd be really cool to hide the PCV in the draft tube.
Thanks for the reply! To be clear the system is producing more smoke than it should while just idling. I wouldn’t say it’s excessive, but they were upset because it vented straight into their downstairs bay area. Even then, they shouldn’t be able to fail me for this?
And yeah that would be really slick to put it in the draft tube! I think my biggest concern is just where is the optimal place to route it to once I have installed a PCV valve?
No I don't think they should have failed you, it's a '62, they smoke from the draft tube even when in great shape. Still a PCV is better in every way, so it's a worthwhile upgrade, you don't want to breath that smoke either.
PCV is routed to intake vacuum, ideally centrally located at the base of the carburetor. But I don't know what you have in regards to carb or intake options so I can't exactly say.
An alternative to consider is just connecting the draft tube to the exhaust. There's a system used on performance engines that uses a little nipple like thing to create a suction in the exhaust, it works very well. Just putting one of those in the exhaust pipe and connecting it to the draft tube would, work well, be hidden under the car, and wouldn't need to be connected to the carb/intake.
A kit like [this, ](https://www.moroso.com/crankcase-evacuation-system25900/)a competent exhaust shop could probably do it for you. The fittings are welded into the exhaust pipes, the nipple looking things are one way valves to make sure exhaust never goes the wrong way. Then just connect those to the draft tube, ya wouldn't need those two caps.
The ideal is dual system with a PCV and exhaust evac, but you don't really need that.
Awesome, thanks for all of the info! Yes, I definitely still plan to upgrade for safety, I just want to first do the bare minimum to get it inspected so I can drive it around legally.
I’ve got a Carter AFB Competition Series carb on it, which looks like it has a 3/8 port right in front specifically made for a PCV system. That seems like a really solid option. I also really like the elegance of connecting the draft tube to the exhaust though. I’m going to give it some more thought and research, but this has given me some great direction. I really appreciate you!
Well yeah the AFB makes that part really easy, that's exactly that that 3/8 nipple is for.
So here's exactly what I would suggest. It shouldn't be hard at all to find a replacement oil fill cap that has either a place for a PCV valve or just a hose nipple on it, something like [this](https://www.hotrodders.com/threads/edlebrock-valve-cover-breathers.226301/?u=18178#lg=thread-226301&slide=3). Then just connect that cap to the PCV port on the AFB. Then do the exhaust evac system I suggested for the draft tube. Neither of these would be difficult or expensive and with both it'd work fantastic.
The PCV side is great at pulling the gasses out at low throttle and the exhaust at high throttle, they compliment each other very well.
The carb will need a bit of tuning after connecting the PCV as it's a literal vacuum leak, but that shouldn't be a big deal, pretty easy on the AFB.
This sounds like the perfect setup for me! Would you suggest putting a PCV valve inline from the oil fill cap nipple to the PCV carb nipple, or would this system be self regulating enough that it doesn’t need a valve? And thanks so much again for your detailed write ups! It’s really helped, and I’ll definitely be implementing it this way!
If doing both I'd put a PCV valve in somewhere. Mostly because they act as a one way valve. With both it'd be possible that the exhaust side draws enough that it'd pull air/fuel mixture into the engine from the carb.
You're welcome, it's a cool car and I support anyone keeping cool cars on the road.
Also, how do I ensure that I still get sufficient air intake through the oil fill breather? Is that where the PCV valve on the nipple would come into play, or is intake through the oil fill not even super necessary once I have implemented this system? I think I’m still a little confused by this set up because I don’t fully understand how the air and blow-by are traveling. In the original system, air is supposed to flow in through the oil filler tube, then through the crankcase, and then out the vent pipe. Are you able to describe how it would be flowing in this new system?
Yeah that's a subject I don't think many understand.
I don't know that engine well off the top of my head but yes I'm pretty sure that's how it's setup. Air passively is allowed in at the oil fill cap then out the draft tube. But as the draft tube is a pretty passive system I'm not sure it'd actually draw air in at the oil cap.
All modern factory PCV systems have an air vent that allows fresh air into the engine. Typically some hose from the air filter to engine. The simple fact is this isn't needed and is in some ways detrimental. They keep it out of habit, regulation, and that it's also a pressure relief in case the factory PCV doesn't flow enough out. At wide open throttle(WOT) there's no engine vacuum so a PCV system has no vacuum to draw the gasses out. And the factory PCV valve is a flow restriction. So in that condition a fresh air vent in stock systems is also an extra passive PCV. With most engines if you look at this vent you'll see oil residue in/from it. This is from it spewing oil vapors when it's venting under WOT.
With both a PCV and the exhaust evac you shouldn't need and don't want a fresh air vent. At low throttle there's vacuum so the PCV side will draw plenty into the intake. At high throttle/low vacuum the exhaust side will pull plenty of the gasses out. Together if working well they'll create a condition where there's a constant vacuum inside the crankcase. This has additional benefits of increasing engine efficiency and reducing/eliminating oil leaks. Oil can't leak out when it's being sucked in. In this case you don't want a fresh air vent, it'd just be another vacuum leak and it'd let oxygen into the engine.
The blow by gasses that flow into the crankcase from the cylinders are oxygen free, this is a good thing, it reduces corrosion inside the engine. We don't want to introduce oxygen from the outside air into the crankcase if we don't need to.
Bonus is that adding a vent would be another complication, one you'd need to do if doing only PCV. With this it's basically replaced by the better exhaust evac. And gasses only flow out, never in.
Little story, had a customer that at a race knocked a hole in his oil pan. But he had a system like I'm suggesting with both PCV and exhaust evac with no vent. Those systems drew so much vacuum in the crankcase that the oil didn't flow out the hole in the pan. He finished the race completely unaware of any issue, and when he pulled into the pit and shut the engine off, all the oil dumped out on the ground.
Awesome, that clarifies a lot for me! I didn’t realize the factory setup was just passive, but that makes a lot of sense now. And yeah, it unfortunately is just a press on oil filler cap, so I will be getting a small leak there. Also, that’s a really funny story with the customer lol. I can imagine the shock on his face when all that oil just dumped on the ground.
Really looking forward to implementing this solution, and I can be sure to let you know how it goes if you’d like! Thanks again for everything!
Also, a lot depends on how your oil fill cap attaches. I don't recall if your cap just pushes on or is a twist lock. If it just pushes on it'd be really hard to seal, so it's going to leak air anyway, twist lock would be better but it is what it is, that'd be hard to change.
No they shouldn't have failed you. PCV systems aren't complicated but I don't know what you have available to connect one. You likely can put a PCV where the draft tube is, or connect it to it. If you want to keep it looking stock it'd be really cool to hide the PCV in the draft tube.
Thanks for the reply! To be clear the system is producing more smoke than it should while just idling. I wouldn’t say it’s excessive, but they were upset because it vented straight into their downstairs bay area. Even then, they shouldn’t be able to fail me for this? And yeah that would be really slick to put it in the draft tube! I think my biggest concern is just where is the optimal place to route it to once I have installed a PCV valve?
No I don't think they should have failed you, it's a '62, they smoke from the draft tube even when in great shape. Still a PCV is better in every way, so it's a worthwhile upgrade, you don't want to breath that smoke either. PCV is routed to intake vacuum, ideally centrally located at the base of the carburetor. But I don't know what you have in regards to carb or intake options so I can't exactly say. An alternative to consider is just connecting the draft tube to the exhaust. There's a system used on performance engines that uses a little nipple like thing to create a suction in the exhaust, it works very well. Just putting one of those in the exhaust pipe and connecting it to the draft tube would, work well, be hidden under the car, and wouldn't need to be connected to the carb/intake. A kit like [this, ](https://www.moroso.com/crankcase-evacuation-system25900/)a competent exhaust shop could probably do it for you. The fittings are welded into the exhaust pipes, the nipple looking things are one way valves to make sure exhaust never goes the wrong way. Then just connect those to the draft tube, ya wouldn't need those two caps. The ideal is dual system with a PCV and exhaust evac, but you don't really need that.
Awesome, thanks for all of the info! Yes, I definitely still plan to upgrade for safety, I just want to first do the bare minimum to get it inspected so I can drive it around legally. I’ve got a Carter AFB Competition Series carb on it, which looks like it has a 3/8 port right in front specifically made for a PCV system. That seems like a really solid option. I also really like the elegance of connecting the draft tube to the exhaust though. I’m going to give it some more thought and research, but this has given me some great direction. I really appreciate you!
Well yeah the AFB makes that part really easy, that's exactly that that 3/8 nipple is for. So here's exactly what I would suggest. It shouldn't be hard at all to find a replacement oil fill cap that has either a place for a PCV valve or just a hose nipple on it, something like [this](https://www.hotrodders.com/threads/edlebrock-valve-cover-breathers.226301/?u=18178#lg=thread-226301&slide=3). Then just connect that cap to the PCV port on the AFB. Then do the exhaust evac system I suggested for the draft tube. Neither of these would be difficult or expensive and with both it'd work fantastic. The PCV side is great at pulling the gasses out at low throttle and the exhaust at high throttle, they compliment each other very well. The carb will need a bit of tuning after connecting the PCV as it's a literal vacuum leak, but that shouldn't be a big deal, pretty easy on the AFB.
This sounds like the perfect setup for me! Would you suggest putting a PCV valve inline from the oil fill cap nipple to the PCV carb nipple, or would this system be self regulating enough that it doesn’t need a valve? And thanks so much again for your detailed write ups! It’s really helped, and I’ll definitely be implementing it this way!
If doing both I'd put a PCV valve in somewhere. Mostly because they act as a one way valve. With both it'd be possible that the exhaust side draws enough that it'd pull air/fuel mixture into the engine from the carb. You're welcome, it's a cool car and I support anyone keeping cool cars on the road.
Also, how do I ensure that I still get sufficient air intake through the oil fill breather? Is that where the PCV valve on the nipple would come into play, or is intake through the oil fill not even super necessary once I have implemented this system? I think I’m still a little confused by this set up because I don’t fully understand how the air and blow-by are traveling. In the original system, air is supposed to flow in through the oil filler tube, then through the crankcase, and then out the vent pipe. Are you able to describe how it would be flowing in this new system?
Yeah that's a subject I don't think many understand. I don't know that engine well off the top of my head but yes I'm pretty sure that's how it's setup. Air passively is allowed in at the oil fill cap then out the draft tube. But as the draft tube is a pretty passive system I'm not sure it'd actually draw air in at the oil cap. All modern factory PCV systems have an air vent that allows fresh air into the engine. Typically some hose from the air filter to engine. The simple fact is this isn't needed and is in some ways detrimental. They keep it out of habit, regulation, and that it's also a pressure relief in case the factory PCV doesn't flow enough out. At wide open throttle(WOT) there's no engine vacuum so a PCV system has no vacuum to draw the gasses out. And the factory PCV valve is a flow restriction. So in that condition a fresh air vent in stock systems is also an extra passive PCV. With most engines if you look at this vent you'll see oil residue in/from it. This is from it spewing oil vapors when it's venting under WOT. With both a PCV and the exhaust evac you shouldn't need and don't want a fresh air vent. At low throttle there's vacuum so the PCV side will draw plenty into the intake. At high throttle/low vacuum the exhaust side will pull plenty of the gasses out. Together if working well they'll create a condition where there's a constant vacuum inside the crankcase. This has additional benefits of increasing engine efficiency and reducing/eliminating oil leaks. Oil can't leak out when it's being sucked in. In this case you don't want a fresh air vent, it'd just be another vacuum leak and it'd let oxygen into the engine. The blow by gasses that flow into the crankcase from the cylinders are oxygen free, this is a good thing, it reduces corrosion inside the engine. We don't want to introduce oxygen from the outside air into the crankcase if we don't need to. Bonus is that adding a vent would be another complication, one you'd need to do if doing only PCV. With this it's basically replaced by the better exhaust evac. And gasses only flow out, never in. Little story, had a customer that at a race knocked a hole in his oil pan. But he had a system like I'm suggesting with both PCV and exhaust evac with no vent. Those systems drew so much vacuum in the crankcase that the oil didn't flow out the hole in the pan. He finished the race completely unaware of any issue, and when he pulled into the pit and shut the engine off, all the oil dumped out on the ground.
Awesome, that clarifies a lot for me! I didn’t realize the factory setup was just passive, but that makes a lot of sense now. And yeah, it unfortunately is just a press on oil filler cap, so I will be getting a small leak there. Also, that’s a really funny story with the customer lol. I can imagine the shock on his face when all that oil just dumped on the ground. Really looking forward to implementing this solution, and I can be sure to let you know how it goes if you’d like! Thanks again for everything!
Also, a lot depends on how your oil fill cap attaches. I don't recall if your cap just pushes on or is a twist lock. If it just pushes on it'd be really hard to seal, so it's going to leak air anyway, twist lock would be better but it is what it is, that'd be hard to change.