PCV?

[Andrew Mace]

The document I linked to above is the factory training notes for US-spec 1970 emission control systems, which shows the non-valve setup for 1970 US spec.

I can't look at that (for whatever reason) here at work, but I assume it shows the single Stromberg setup?

 

[Deleted member 8987]

Well, all I can tell you is, if you take a 2100 Holey, or Stromberg two barrel, that was not designed for PCV, most PCV's will draw at idle (pull a hose off the valve cover and put your thumb over it to see) and if you stick a ported vacuum leak like a PCV valve into it, you cannot get it to run right.
Internally, the carb is not designed to compensate for it.
Yes, you can pull out jets and air bleeds and drill, but it's gonna take time and money (parts).
Take a pre-1965 Motorcraft 2 barrel, non-PCV (and yes, 260's were non-PCV, with a road draft tube port machined into the flat triagnle in the back of the intake) and try to put it on a post-1965, and you will have issues, like the mixture screws will fall out before you can get it rich enough to idle correctly.
On my Willys with a 3/4 race Merc flatmotor, we went to an Offy 4bbl intake with a PCV designed 390CFM Holley 4bbl, and that works with PCV.
How well does your SU-equipped, non-PCV engine idel if you pull a small vacuum line off the intake?
Once you know the orofice size of the PCV you are using, introduce that size leak and try to gte it adjusted.
You most likely can, but at what cost?
Are you throwing more fuel to it to compensate for a vacuum leak?

I have never tried to put a PCV on a non-PCV LBC, but I have installed road draft tubes and eliminated the PCV, and that you could adjust for.

 

[doates]

Thanks Everyone,

When I got the car it had a single Zenith on it and I think the valve cover was plumbed somewhat like the manual posted above. In the trunk was a set of SU's, a manifold for them and a Smith's PCV in pieces. It is now plumbed exactly like the diagram that Andrew posted.

I have never felt like I had enough pieces inside the Smith's valve. Tonight I took the cover off of the valve and convinced myself that it could not be right so I dug out the boxes of old parts and rummaged through. I found a metal disc with a 1/2" long stud sticking out of it and a light gauge spring about 1" in diameter and 1" long that look suspiciously like they belong in the PCV valve but I don't know because I can't find a diagram of the interior of the Smith's valve anywhere.

If anyone can post a picture, diagram or description of the interior of a Smith's PCV valve it would be greatly appreciated.

Thanks in Advance

Dennis

I will post pictures as soon as I can find the cable to transfer them to my computer.

 

[Andrew Mace]

Sounds like you have everything except the diaphragm.

 

[doates]

Here is a link to pictures. Hope it works.

I assume the spring and disc go in spring down with the stud in the disc pointing down and then diaphragm on top. Actually I am assuming that these parts go in the valve; like I said I found them in a box of old parts. I have a new diaphragm just not pictured.

https://s23.photobucket.com/home/dennis_oates/index

Thanks Again

Dennis

 

[DanB]

I posted this before... On my 66 TR4A, I replaced the PCV with a "catch can" using a Harbor Freight air compressor inline filter. What you need to do is allow enough vacuum to the crankcase to suck the fumes out, but more importantly to maintain a slight vacuum in the crankcase to keep the rear main seal from leaking. Using the Harbor Freight filter, it has a clear case so I can see any oil build up and drain it out as necessary.

Do a google search on Catch Cans. There are a lot of folks using them on later model cars, and you can even buy a can designed for that use.

So far, my solution has worked, but I haven't really driven the car a whole lot.

Dan B.
South Charleston, WV
66 TR4AIRS EFI Megasquirt
80 TR7 DHC

 

[TR3driver]

There is a cutaway view in this document:
https://docs.google.com/viewer?a=v&p...mNGMz&hl=en
that might help.

 

[TR3driver]

I can't look at that (for whatever reason) here at work, but I assume it shows the single Stromberg setup?

Yup.

 

[doates]

What a difference a couple little parts make. I found the disc and spring in a box with old clutch parts and an exhaust manifold. My wife hassles me for never throwing any thing away.

I installed them this morning per the diagram above. It has been taking me several cranks to get it started, now it fires up on the 1st crank. My idle dropped from about 1200 to 600. I actually turned the idle adjust screws in so they are now touching something. It needs a little carb adjustment but it is too wet outside to really work on it. Took it for a spin in the neighborhood and it was smooth and peppy. When I got to third gear I felt my overdrive kick in for the 1st time (the switch was on by accident).

I am stoked!

Thanks for all the help

Dennis

 

[Deleted member 8987]

Yup.
You had a massive vacuum leak.

One way to tell if your system is functioning with the pressures in the crankcase, is take your UniSyn, remove the filler cap, place the UniSyn on the opening after you start the car.
See what you are cold, drive it, see what it is hot, idle and revved.
If it gets to the point it won't lift the ball anymore (hot and revved is most critical), your crankcase pressures are exceeding the ability of the PVC to vent, and the pressure is going to start forcing oil out various places.

When you get to zero vacuum, and then pressure in the crankcase, it's time to re-install a road draft tube until the next re-ring.