The Stovebolt Site Forums The Shop Area Engine Shop New PCV on a 216

After installing a PCV in the top of my draft tube and connecting it to the intake manifold. I’m experiencing a harder start.

1) What adjustments may be required? Will this make it run rich or lean?

2) Will or should the truck run better?

3) I installed the V237 as recommended. How do I know it’s right and working properly?

Thanks for the help, Don

I took some pictures with an iPhone and dumbed them down to 133kb. But for some other reason I was not able to get them excepted.

Don,

Does your 216 have a rear main seal that would allow the inside of the engine to actually hold a vacuum? If not, a PCV system will just pull contaminants in through the rear main bearing area. That was the case on my '36 Chevy 206 engine and I had to abandon the idea of adding PCV.

If I were building the engine today I would try to adapt in a rear main seal. But when I assembled the engine 45 years ago adding PCV was not even a fantasy.

Well Yar this I the first I’ve heard of this in all the posts about making the change.

Don

1940 was the first 216 to use a rear main seal.

"Well Yar this I the first I’ve heard of this in all the posts about making the change."

Don,

I didn't know either until I built a complete PCV system and found that there was no vacuum in the crankcase with the engine creating 21 inches of vacuum idling. So I attached my AC service vacuum pump and turned it on and heard the noise of air rushing into the crankcase through the back of the engine. Checking further I found that the engine has a huge oil drain-back passage between the pan and the slinger on the back of the crankshaft. Prior to that I thought that the only opening to outside air at the back of the crankshaft was the rear main bearing clearance. Live and learn, huh?

I'm sorry to be a bearer of bad news Don but unless a rear main seal is added the PCV system won't work.

My '36 restored pickup pickup has been running since 1976 with the draft tube system so I guess it'll stay like that forever.

Yar^^^^

Anyone have any posts pertaining to my original questions?

Don

Either your PCV has a huge orifice in it, or you have a problem other than the PCV.
Check your engine vacuum at idle with, and then without the PCV in the loop.

Going to this afternoon. The valve I a standard V237. This is where I don’t shine. Figuring out issues. I did expect it to run differently after the PCV add and the new exhaust system.

Thx Don

I was hoping someone would say, “well when you make that change, be sure to look for or check if.......

Don

Don, the PCV I added to the 235 didn't make much noticeable difference in the running. At least not yet. It runs leaner...and I expected that, but the engine vacuum isn't much lower. I used a 3/8 inch hose from the intake manifold to the modified crankcase draft tube and then I used a 1/4 inch reducer at the valve cover because I wanted more negative pressure inside the engine. It seems to be doing ok and as the engine has been rebuilt there's not a great amount of blow-by anyhow. Good luck.
Jon

Jon
I’m not really experiencing any problems. Wasn’t sure until this afternoon but it turns out my rough idle is caused by a bad plug wire. I also adjusted the idle mixture a smidg.

Thank for your reply, Don

Just as I predicted. An unrelated issue, You are welcome...

Sorry to have not given credit to you but it was your post the pointed me in the right direction. This is how I installed the PCV in my 216

Thx Don

Very clean looking setup there Don!
I wasn't looking for credit. I am so full of crap, sometimes I annoy myself.

Thanks Carl

Don

Don, that is a very nice PVC setup. It'd pass for stock to many casual fans. I'd copy your work but I'm running vacuum wipers and suspect I'd have insufficient vacuum for both the PVC and wipers?

I added a PCV to my 49 216 back in 2013 and it reduced the amount of smokey blowby from the 3 valve cover vents and didn't cause any problems with overall engine performance. I originally tried Deve's mod but the lower end of my 216's engine is well worn and produced too much oil film residue in the intake vacuum port. So I modified the draft tube to put more baffles and space between the PCV and crankcase and this reduced the oil film deposits in the intake to almost nil...
Below is a copy of the final setup thats I've been running for approx 20k miles. The vacuum wipers do work and have worked many times with this final setup.