Some PCV Valves can be installed backwards.  A PCV valve can be thought of as a controlled vacuum leak and since most PCV valves used are not application specific to our engines, it can be too much of a leak for the combo.  The best you can do for an off-the-shelf valve is to use a pcv valve from a similar size and power engine.  There is an adjustable, rebuildable valve on the market but it is more expensive than most seem to want to spend. http://mewagner.com/

However, the way you describe yours, I'm either not understanding or it is installed totally incorrectly.  When you say exhaust tube, do you mean the exhaust pipe?  The valve should be between the crankcase and carburetor


Lawrenceville, GA

Charlie,
The tube I'm taking about is the old crankcase tube that sucked the fumes out of the crankcase.
It hung over the back of the engine and the fumes escaped under the car. Drag tube ?
Any how, I opened up the idle circuit screws  to 2.5 turns, hooked up the vacuum gauge and closed the idle screws one turn and got between 19 and 20 inches of vacuum. Also adjusted the throttle screw and the idle is now 650 rpm.
BUT !! the exhaust manifold temp on left is 544 degrees and on the right it is 491 to 480 a big difference and closer for both sides.
What would you day the exhaust temp should be at the cylinder closest to the firewall ?

You have a Thunderbird Cover. That Tube should be removed and PCV plugged directly into Pushrod Cover. Is there a Reason U used it to hookup a PCV?. The PCV  can allow too much Air to pass into Carb at Idle. Trying a PCV from a smaller Engine my help or try restricting the Hose from PCV to Carb. Cut down Airflow. 

  

will give it a try, restrict air flow on the PVC
Thanks,
Tim
Waiting Room for Heaven, Fl 33706

The PCV Hookup must be Airtight with the only "Air" intake being from Valley Cover. The PCV I have on mine is a Fram FV411. I plugged it in and worked very well with no further Modification. PCV Valve is Sometimes Trial and Error to get One that works for your Installation. It sounds like You have some Adjustments to make to Carb. I would suggest disconnecting and plugging PCV hookup and setup Carb without it. Once U have adjusted properly plug the PCV back in and make Mods so it works without excessive Air passing at Idle. Then You will at least know any Problem is from PCV.

  

As a test, to find out if the pcv valve is causing the high idle, simply disconnect it from the carb and plug the port on the carb.  You won't hurt a thing to run it at idle like that for a test.

I don't know what manifold temperature should be for a good running engine.


Lawrenceville, GA

Next Step
I have a K&N air filter with a hole in the bottom of the filter base.
I'll run the PCV hose into this hole and then the oil fumes will pass
into the air filter. This way the carb is bypassed and out of the picture !
Hopefully no air leaks.
Will advise if this plan works.
Thanks for your input, it has been helpful a true learning moment.
Tim
Downtown, Florida 33706

PCV stands for Positive Crankcase Ventilation. Sticking the Hose in the Air Cleaner is useless. The Valve must be hooked to Engine Vacuum to draw Fumes from the inside the Engine. As Charlie and I both suggested unplug the PCV and cap the Vacuum inlet on Carb and setup the Carb first so its working correctly and then deal with the PCV. By the sounds of what You are describing You have Vacuum leak Issues.

  

Try it as mark and Charlie suggested. The opening on the air cleaner bottom is made to use from a sealed oil filler cap for a “closed PCV” system. The factory oil fill cap is used on an “open PCV” system. Goggle that and you’ll see the difference and how they work.

I run both my y blocks with closed systems, using this type of cap to the air cleaner. The PVC valve is in the valley cover (with a baffle under it), then to the PCV port on the carb.

The fill cap looks like this. I don’t know if this fits our oil fill tubes.

I’ve also used this grommet as the PCV grommet in the valley cover. Again, I’m not sure this item is exactly the one you need.

https://www.summitracing.com/parts/mor-68772

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I used that Grommet too. Works well. You will need a smaller Grommet to hold the PCV. Grommet will fit inside the bigger Grommet. I used Super Glue to bond the 2 together otherwise the smaller One works out of the bigger one. It almost sounds like He has a Thunderbird Cover. If so you just need a Grommet to go in the Cover once U remove the existing Tube. Already has a Baffle underneath.