olds 307 and 403

On the Olds 260 in my 70 Cutlass, both valve covers have had PCV valves and grommets. It looks like factory GM blue paint on the valve covers, just weird.

MDchanic

Makes no sense - the PCV pulls air into the intake from the crankcase on one side, and from the air cleaner into the crankcase from the other side -- If it's pulling into the intake from both sides, where would the air be coming into the crankcase from?

- Eric

joe_padavano

Olds used dual ventilation on W-30s and MT cars. This involved two breather pipes to the valve covers, however. There was still only one PCV valve that attached to the nipple on the intake valley. As Eric points out, there is no need for two PCV valves. Considering that your 260 didn't grow in that 1970, it's obviously been messed with.

Octania

That's because folks who don't know what they are doing continue to work on stuff. I too have made mistakes because I did not understand the mechanism I was working on.


I recommend you return it to the factory setup- one PCV valve, one filter/ breather vented to the air cleaner housing.

Allan R

Huh?? Why??

Fun71

You could put an oil fill tube breather on it and keep the dual PCV valves.
I don't know if this would fit but the early Olds engines used something similar.

joe_padavano

Why? Simply change the grommet on one valve cover to a breather grommet, just like Ransom E. intended...

Fun71

Just providing information and ideas so he has options.

oldcutlass

The claim is cleaner oil from contaminants and better ring seal. But both PCV's are in the same VC and a breather on the other side.

olds 307 and 403

Just strange that someone did this. The original 350 was seized supposedly. I am running the pcv valve to the proper port and the other I put the hose from the extra pcv valve to the breather filter in the air cleaner. I will probably just add a plumbing fitting. It didn't use or leak a drop of oil driving 500 km this weekend. It is surprisingly decent especially with the kick down working and with the open top on the air filter plus the dual exhaust.

olds 307 and 403

I also got 21 mpg imperial.