Convert 170 from breather tube to PCV system

[2door 61]

My 61 Valiant still has the original breather tube system on the valve cover.
I’d like to change it over to a PCV system.
The base of the carb. has a vacuum port but I want to be sure making the change won’t have an adverse effect on the engine.
Any input would be greatly appreciated.

 

[pishta]

The PCV valve is shut during high vacuum idle and spring loaded WOT, it only opens at mid throttle where it WILL lean it out a little but should not affect driveability. you just need to adapt the downdraft tube to a PCV like the 64-65 273 had: a metal PCV valve in a stove pipe hat.

 

[Johnny Dart]

6cyl or V8 car ?

Edit: I opened my eyes. So you have a slant 6, with a road draft tube.
As Pishta mentioned, get a push on PCV valve, and hook it up to the appropriate place on the carb. You might have to re-adjust the settings on your carb.

 

[RustyRatRod]

My 61 Valiant still has the original breather tube system on the valve cover.
I’d like to change it over to a PCV system.
The base of the carb. has a vacuum port but I want to be sure making the change won’t have an adverse effect on the engine.
Any input would be greatly appreciated.

I'll tell you what I did to my 64. It already had a PCV. The oil fill cap was also the crankcase vent from the factory. I put a one year later air filter with the tube for the crankcase hose that attaches to an oil fill cap that also has the hose. This oil fill cap is not vented to the atmosphere like the original one, but sealed except for the tube where the air cleaner hose connects. You could simply do the same by adding a PCV valve and the later air cleaner and oil fill cap like I did. @slantsixdan is very sharp on this stuff. He might have a better way.

 

[Johnny Dart]

No reason to make it anymore difficult than it is.
Here's what you are shooting for. Simple stuff.

 

[pishta]

^^^ just like that^^^

Just remember you need an inlet for the PCV to pull air into the case, it cannot be sealed with just a vacuum source off the valve cover. Oil filler is the inlet, usually has a hefty baffle under it as well as some fiberous material inside.

 

[slantsixdan]

You won't need to change your oil fill/breather cap; the same one was used with the road draft tube and with '61-'64 (California) '61-'68 (rest of the states + Canada) PCV systems.

If your carburetor has a big vacuum port at the base (presumably it's capped right now), then it's already calibrated to account for airflow from the PCV valve.

Remove the road draft tube, install a PCV cap and valve, run a length of appropriately oilproof hose from the PCV valve to the carburetor port, readjust your idle mixture and speed, and you're all set. The PCV cap you'd need to keep using your pre-'66 valve cover looks like a roughly 2" diameter metal version of an aerosol spray can cap, with a hole in the middle, and it uses a 2-legged steel spring to hold it firmly to the valve cover chimney. Here's a new one.

Picking a PCV valve requires some caution; many different valves will fit and look alike, but they have different flow characteristics and spring calibrations. The 170 engine takes a different valve than all the larger engines.

The original '61-'63 valves were a metal item made by AC and designed to be taken apart for cleaning. I might still have one or two of those new in box (and the separate metal elbow they take); ping me if you want me to check.

If you don't want to mess with hunting up obsolete parts and you'd prefer to shop for a current-production PCV valve, the one you want is Standard № V253. These currently-available PCV valves are a different style, made partly or completely out of plastic, and require some adaptation to use with the pre-'66 valve cover and PCV cap. You make a sandwich in this order: PCV valve (push the non-hose end through the cap from outside to inside), spring retainer, grommet (push onto non-hose end of PCV valve from the bottom). Sometimes the spring retainer won't fit over the plastic valve and you have to leave it off. Push this "sandwich" onto the valve cover chimney. It won't look quite original, but it'll fit and work fine:

 

[2door 61]

You won't need to change your oil fill/breather cap; the same one was used with the road draft tube and with '61-'64 (California) '61-'68 (rest of the states + Canada) PCV systems.

If your carburetor has a big vacuum port at the base (presumably it's capped right now), then it's already calibrated to account for airflow from the PCV valve.

Remove the road draft tube, install a PCV cap and valve, run a length of appropriately oilproof hose from the PCV valve to the carburetor port, readjust your idle mixture and speed, and you're all set. The PCV cap you'd need to keep using your pre-'66 valve cover looks like a roughly 2" diameter metal version of an aerosol spray can cap, with a hole in the middle, and it uses a 2-legged steel spring to hold it firmly to the valve cover chimney. Here's a new one.

Picking a PCV valve requires some caution; many different valves will fit and look alike, but they have different flow characteristics and spring calibrations. The 170 engine takes a different valve than all the larger engines.

The original '61-'63 valves were a metal item made by AC and designed to be taken apart for cleaning. I might still have one or two of those new in box (and the separate metal elbow they take); ping me if you want me to check.

If you don't want to mess with hunting up obsolete parts and you'd prefer to shop for a current-production PCV valve, the one you want is Standard № V253. These currently-available PCV valves are a different style, made partly or completely out of plastic, and require some adaptation to use with the pre-'66 valve cover and PCV cap. You make a sandwich in this order: PCV valve (push the non-hose end through the cap from outside to inside), spring retainer, grommet (push onto non-hose end of PCV valve from the bottom). Sometimes the spring retainer won't fit over the plastic valve and you have to leave it off. Push this "sandwich" onto the valve cover chimney. It won't look quite original, but it'll fit and work fine:
View attachment 1715497659

Thanks for the info. . I would appreciate an original valve if you have one. Thanks Ken

 

[Perseus]

You won't need to change your oil fill/breather cap; the same one was used with the road draft tube and with '61-'64 (California) '61-'68 (rest of the states + Canada) PCV systems.

If your carburetor has a big vacuum port at the base (presumably it's capped right now), then it's already calibrated to account for airflow from the PCV valve.

Remove the road draft tube, install a PCV cap and valve, run a length of appropriately oilproof hose from the PCV valve to the carburetor port, readjust your idle mixture and speed, and you're all set. The PCV cap you'd need to keep using your pre-'66 valve cover looks like a roughly 2" diameter metal version of an aerosol spray can cap, with a hole in the middle, and it uses a 2-legged steel spring to hold it firmly to the valve cover chimney. Here's a new one.

Picking a PCV valve requires some caution; many different valves will fit and look alike, but they have different flow characteristics and spring calibrations. The 170 engine takes a different valve than all the larger engines.

The original '61-'63 valves were a metal item made by AC and designed to be taken apart for cleaning. I might still have one or two of those new in box (and the separate metal elbow they take); ping me if you want me to check.

If you don't want to mess with hunting up obsolete parts and you'd prefer to shop for a current-production PCV valve, the one you want is Standard № V253. These currently-available PCV valves are a different style, made partly or completely out of plastic, and require some adaptation to use with the pre-'66 valve cover and PCV cap. You make a sandwich in this order: PCV valve (push the non-hose end through the cap from outside to inside), spring retainer, grommet (push onto non-hose end of PCV valve from the bottom). Sometimes the spring retainer won't fit over the plastic valve and you have to leave it off. Push this "sandwich" onto the valve cover chimney. It won't look quite original, but it'll fit and work fine:
View attachment 1715497659

Hi Dan,
I have a '65 Dart with the '65 valve cover. I want to order this same setup with the cap, retainer and grommet, but my engine is the 225. What current-production PCV should I order to fit the cap instead of the #V253? When I bought my Dart before this year it came with NO PCV system at all, just 2 breather caps, so I cobbled one together, but I know it's not optimum. Thanks ahead for your advice.

 

[slantsixdan]

That'll be a № V165.

 

[Perseus]

That'll be a № V165.

Thanks for the info. and getting back.

 

[valiantpatrol]

Wanted to ad that , for every 1960 I've converted, the intake was not drilled which prevented the carb port from having vacuum. I believe '61 was a transition year and may or may not be drilled. I've never seen a '62 or later that wasn't drilled which is why I say '61 may be a transition year. It was an easy enough fix but requires removing the carb and drilling a hole in the intake. Also easy to check just remove the plug on the carb port you were going to hook it to while it's running to confirm there is suction.

 

[2door 61]

Wanted to ad that , for every 1960 I've converted, the intake was not drilled which prevented the carb port from having vacuum. I believe '61 was a transition year and may or may not be drilled. I've never seen a '62 or later that wasn't drilled which is why I say '61 may be a transition year. It was an easy enough fix but requires removing the carb and drilling a hole in the intake. Also easy to check just remove the plug on the carb port you were going to hook it to while it's running to confirm there is suction.

Thanks for that info. the car is out being painted and my first job is the PCV once I get it back. I’ll let you know what I find.

 

[slantsixdan]

Wanted to ad that , for every 1960 I've converted, the intake was not drilled which prevented the carb port from having vacuum. I believe '61 was a transition year and may or may not be drilled.

All '60 intakes were aluminum and undrilled. All '61 intakes were cast iron and drilled. This will not be an issue unless someone has swapped an aluminum '60 intake onto the '61 car.

It was an easy enough fix but requires removing the carb and drilling a hole in the intake.

Not quite that straightforward. The '61+ carb mount pad was enlarged to provide room for the PCV port to be drilled. If you try to drill this hole in the correct location on the un-enlarged '60 carb mount pad, you stand an excellent chance of creating a big ol' vacuum leak. There is a way around this that isn't terribly difficult, but requires some careful work with appropriate tools. But none of this matters when we're dealing with a '61 intake.

 

[famous bob]

All '60 intakes were aluminum and undrilled. All '61 intakes were cast iron and drilled. This will not be an issue unless someone has swapped an aluminum '60 intake onto the '61 car.



Not quite that straightforward. The '61+ carb mount pad was enlarged to provide room for the PCV port to be drilled. If you try to drill this hole in the correct location on the un-enlarged '60 carb mount pad, you stand an excellent chance of creating a big ol' vacuum leak. There is a way around this that isn't terribly difficult, but requires some careful work with appropriate tools. But none of this matters when we're dealing with a '61 intake.

A little off topic here, but what pcv valve would work best on bigger stroker engines/ off the shelf only, not going to pay $75 for one .??????

 

[slantsixdan]

Who's trying to get you to pay $75 for a freakin' PCV valve? What, like, a special racing PCV valve guaranteed to shave nine seconds off your ETs or somethin'? Shishkebab. If you're building a special stroker engine, I'm guessing you're paying careful attention to piston clearances and ring gaps and you're going to break it in carefully, etc, so there shouldn't be unusually high volumes of crankcase gas to handle. The smaller valve for the 170 Slant-6 seems like it would imply you need a bigger valve for an extra-big engine, but you don't. The same V165 valve was used on everything from the 225 up through the 426, just as there's one PCV valve that was used on the '66 Studebakers with the 230 Six and '72 Cadillacs with the 472 V8.

 

[famous bob]

Who's trying to get you to pay $75 for a freakin' PCV valve? What, like, a special racing PCV valve guaranteed to shave nine seconds off your ETs or somethin'? Shishkebab. If you're building a special stroker engine, I'm guessing you're paying careful attention to piston clearances and ring gaps and you're going to break it in carefully, etc, so there shouldn't be unusually high volumes of crankcase gas to handle. The smaller valve for the 170 Slant-6 seems like it would imply you need a bigger valve for an extra-big engine, but you don't. The same V165 valve was used on everything from the 225 up through the 426, just as there's one PCV valve that was used on the '66 Studebakers with the 230 Six and '72 Cadillacs with the 472 V8.

not slant 6 related
There is an aftermarket alum. valve that is way high on price, wagner I think, never paid to much attention at that price. supposed to be a 2 stage -----adjustable , a couple of guys on here say its the best hing since sliced bread , and well worth it . The valve I have on my 505 opens completely and closes completely, its all the way or nothing.

 

[slantsixdan]

My knowledge extends as far as how PCV systems work (and don't work) in street-driven engines. There may be special crankcase circumstances and needs in a high-holy race motor that I am not aware of.