PCV Valve

[Guest sintid58]

While working on the Skylark yesterday I noticed the pcv valve is not hooked to anything. It has been years since I have worked on a car with this type of plumging. Where should the pcv valve be hooked to, the air cleaner seems to be where I would think it should go but there is no place to hook it there. On this car the pcv valve seems to be in the rear of the valley between the head and the valve itself is there but the hose has been cut off on top and is hooked to nothing. Thanks.

[TxBuicks]

Try looking at the back of the carb on the bottom plate.

[Guest sintid58]

I did that already and there is an outlet that has the vacum hose going to the tank for the A/C contols hooked to it but nothing else. Do I need to put a T in the line there and hook the pcv to that?

[NTX5467]

The pcv valve should be hooked to "manifold vacuum" rather than "ported vacuum". The hookup should be the same as the hose size that fits the "output" side of the valve, typically about 3/8" hose. Look on the back of the carb for a fitting (or a threaded hole with a plug in it) or on the front of the carb, near the middle (in either front or back--depending upon the type and such of the carb, plus OEM or aftermarket) provided the carb is of the correct vintage to accept a pcv valve line. Usually, the pcv line would hook to the carb rather than the intake manifold directly. Knowing what carb is on there could help determine where the hookup for the pcv line should be.

Enjoy!

NTX5467

[Guest sintid58]

The car has a 600 CFM Edlebrock model 1405 Carberatour on it. I have not looked real closely at it but coming from the rear of the carb at the base is a hose that goes to the vacum canister on the firewall that runs the A/C controls. I was thinking that maybe that should have a T in it to hook the PCV valve to. There is nothing to hook to now. As much of a vacum leak as would be caused by not having the pcv hooked up would cause the car to barely run so either there is no spot to hook it too or the place where it should hook is covered. I suspect that when the previous owner put this carb on it he just plumbed the vacum canister to the carb and left the pcv unhooked. I would be afraid that you would get a lot of pressure in the crankcase doing this because there is no breather either, so I would like to hook it up asap. I also seem to remember that if your pcv valve was not operating properly it could effect gas mileage. The car runs great and there are no leaks and I would like to keep it that way. I do have a quadrajet but it needs a rebuild and this edlebrock is new so I would just as soon keep it on the car if possible.

[NTX5467]

After checking the Edelbrock website for verification, the pcv fitting is in the normal location for the AFBs of Carter or Edelbrock--in the middle of the front of the carb, between the two idle mixture screws. It could be that for GM/universal applications, the rear fitting would be for the power brake vac source (i.e., much larger than an a/c vacuum line!). Other than that, I don't recall any vac fitting on the rear of an AFB or the Edelbrock variation. There will be two smaller vacuum fittings (maybe only one in some cases) to run the vacuum advance in the distributor (ported vac), the vac diaphram in the factory "hot air" air cleaner (manifold vac), and something else of smaller vacuum demands.

Typically, GM used a "vacuum tree" to source the hvac vacuum and related items (not related to emissions), the automatic transmission's vacuum modulator valve, and possibly the power brake booster's vacuum. This would screw into a rear runner of the intake manifold.

If you don't have a breather in a valve cover, there needs to be one, whether as a dedicated breather or as a combination oil filler cap and breather. THIS would be the main source of the "air" in the crankcase which the pcv valve would then recycle into the engine. The fuel metering curves of the carburetors are calibrated to include that crankcase air flow in their total calibration package.

No additional (and compensatd for) pcv "air" would make the idle speed adjustment a little "off", as would be the mixture (very possibly), but I suspect it would not really impact "main system" fuel economy or performance if it was not there. With the idle system, the additional air would be significant in its presence or absence, in relation to the total air flow in that operating mode, but would not be very significant with additional air flow when the carb's main system is working at greater-than-idle operational mode.

You can probably download the information you would need to do the hookups and such from the Edelbrock.com website. When you get to the area for the AFB carbs, there is a link (1.8GB PDF) to the AFB Owner's Manual. On page 21, it has an exploded view of the 1406-style carb. LH vacuum port is full manifold vacuum, middle large fitting is for the pcv, RH vacuum port is ported vacuum (i.e., distributor vac advance and possibly emissions canister purge on newer vehicles).

Enjoy!

NTX5467

[Guest sintid58]

THanks, this car does not have power brakes, it does have power steering and factory A/C. I imagine when the former owner put the carb on he just plumbed into the easiest port for the vacum canister. I will look into the from of the carb for a port to hook the pcv to. He also has the hose for the hot air valve in the air cleaner just hanging loose from the air cleaner and pluged with a screw. So now I can hook that up also.

[NTX5467]

Thanks for the additional information. It should be pretty easy to get those things configured and attached to the places they need to be. The air cleaner line should be attached to manifold vacuum (the one by the idle speed screw--as many AFBs and AVSs were OEM on Chrysler products, where the main and/or primary snorkle was on the driver's side, the manifold vac port being on that side fits that scenario, too). The AFB Owner's Manual from the Edelbrock website is pretty good at showing you how the carb is set up and can be tuned.

Take care,

NTX5467

[Guest sintid58]

Thanks for the info, I went onto the Edlebrock web site and printed out the pictures. Once I actually took the time to look at the carb all the fittings were there just had to pull off the caps. I went to the parts store and got some vacum hoses and put all new on and everything seems to work fine. It was really nice here yesterday so we actually took the car out for a short drive. This car has a bit of a cam and the 4 barrel carb on it. After having the Stage 1 455 so long I am very glad I didn't buy a new Skylark with a 2 barrel. It does ride a lot better than the GSX did. I have one more thing to do to the engine before we drive it a lot. The guy I bought it from must have been worried about it getting hot or he had problems, he has either a 140 or 160 thermostat in it and an electric fan plus had put on a carbon fiber fan blade. Yesterday we put the orinal fan on which he told me had a new clutch on it and I want to put in at least a 180 thermostat in it. I beleive we should get better performance and gas mileage with a hotter thermometer in it. I want to get that done and drive the car as much as possible before we go to Seattle. I can't beleive that if the radiator has been rebuilt as he says it has it will ever get hot, especially with the electric fan as a back up but I want to make sure. I will say one thing about the petronix ignition the car fire up right now, I think it starts better than any car I ever had with points and I know it starts better than my pickup with both efi and electronic ignition. One more question does anyone know what I should gap the plugs at with the new ignition. I am sure it should be wider than standard but not sure how much.

[NTX5467]

I'm glad everything "fell" into place!

I concur, the car needs a 180 degree thermostat in it. From what Vic Edelbrock replied to a friend (about 30 years ago), once you get below about 160 degrees operating temperature, cylinder bore wear increases. The 195 degree thermostats were used in the later 1960s (about 1969 and after) for emissions reasons, but the 180s worked fine before that.

Somewhere, years ago, I saw a chart on power output vs. spark plug gap. Seems that after about .045", there is some more power but it is marginal up to about .060", provided you have a coil that'll fire things off at that gap and related compression ratio (key item, cylinder pressure and compression ratio, especially with NOS). I suspect you'll find the best sweet spot at about .040" or .045" for performance and longevity for a good running street engine.

I have not figured out why some people feel that an old musclecar needs a radiator big enough for a Mack truck. A three-core radiator with a good fan shroud and a factory fan clutch that works should cool fine rather than having to have one of the universal-fit aluminums and such. Adding the electric fan in the front might be good if you get stuck in traffic, though. I also feel that in certain situations (i.e., racing, NOS use), the aluminum radiators can be helpful, or one of the OEM replacement composite (alum core with composite tanks) high efficiency radiators can be an asset.

There is an optimum flow rate vs. cooling rate for any air to water heat exchanger. This also means that there can be too much cooling effect in some cases, if the heat exchanger is too much oversized. In a car, I'd worry more about making sure there was a dedicated air flow through the radiator and not "around" it, plus that the shroud and fan had a good spatial interface (i.e., factory orientation) to each other.

I wonder if he had the radiator recored or "fixed"? Things might look good "up top" on a cross-flow radiator, but be plugged up about 2/3 of the way down--use of an infrared temperature gun could determine that, I suspect.

Sounds like everything's progressing nicely! Keep us posted!

Enjoy!

NTX5467

[Guest sintid58]

It was cool today and windy but sunny and dry so wanting to take advantage of the dry highways and see how the car runs we took it for a long drive. We drove almost 100 miles and the car ran and drove great. The previous owner put in a good set of under dash gauges and the car held steady at 160. I am thinking about pulling the radiator and having it flushed out professionally before we go to Seattle but looking at it today as good as the fins look I think he must have had a new core put in. There should be some pretty hot weekends in June to see how it reacts also. I am not going to take off the electric fan, it might be nice to have in parades and such in hot weather and if there would be any over heating it may come in handy. We are planning on getting the front wheels off and checking the bearings and brakes before spring and the gas gauge doesn't work but a new unit for the gas tank was included with the car. Also their was a new gas tank that someone gave him from a chevelle that they were putting a fuel cell in and a turbo 350 transmission. I am really out of room for all the parts he gave me.