[gto19]

On my completely stock 67 gto ho oil seems to come out of the original oil cap breather some when I’m driving. . I’m gonna replace the cap with a cap from Ames ...maybe seeping past the old rock hard gasket but I think I’m also seeing oil come out from the vent holes . What would cause this . The car runs really good and doesn’t smoke at all that I can see .i replaced the pvc valve also .

[Kenth]

Missing baffle bolted to the head under valve cover, and/or blowby gases escaping?

[gto19]

I think The baffle is there . I can see it through the hole

[coonhunter70]

PCV system not working?

[gto19]

Originally Posted by coonhunter70

PCV system not working?

Good question. I replaced the pvc valve with a new one . I really don’t know how to check it .

[phil400]

I've read alot of the new PCV valves sold are junk these days.

[gto19]

I’ve tried two different pcv valves . The original one in the motor and a new one from orielys

["QUICK-SILVER"]

Originally Posted by gto19

completely stock 67 gto ho .

What kind of gas are you using to fuel this engine?

CA pump gas and factory tune-up specifications will create more blow-by than the PCV can handle. That's also more than normal when the engine is under load and the PCV isn't working because of low vacuum.

Cylinder pressure comes up too fast and too high on the power stroke. Some of that pressure will get past the rings with the piston still up high in the cylinder.

Higher octane fuel would make peak pressure happen with the piston a little further down the bore and the piston moving faster because of crank angle. Makes for less time for high cylinder pressure to leak past the rings.

De-tune for pump fuel by tightening up and limiting ignition timing and advance curve. May or may not run as strong but it will help with the blow-by.

Clay

[gto19]

Yep I live in California and run 91 octane. The car actually pings when I step on it .

Originally Posted by "QUICK-SILVER"

What kind of gas are you using to fuel this engine?

CA pump gas and factory tune-up specifications will create more blow-by than the PCV can handle. That's also more than normal when the engine is under load and the PCV isn't working because of low vacuum.

Cylinder pressure comes up too fast and too high on the power stroke. Some of that pressure will get past the rings with the piston still up high in the cylinder.

Higher octane fuel would make peak pressure happen with the piston a little further down the bore and the piston moving faster because of crank angle. Makes for less time for high cylinder pressure to leak past the rings.

De-tune for pump fuel by tightening up and limiting ignition timing and advance curve. May or may not run as strong but it will help with the blow-by.

Clay

[mgarblik]

If the engine has a pinging noise you can hear while driving, that MUST be addressed right away. If you can hear it damage IS happening. How much is hard to determine. Generally if you can hear the engine ping, the top piston rings will lose the Molly inlay in the ring and also radial tension. Then the engine will begin using more oil and the ping will increase. I would recommend retarding the ignition as a stop gap easy to do item until more proper repairs can be made. The overwhelming of the PCV system is almost always caused by excessive blowby from a worn or damaged engine rotating assembly. Make sure grommets, hoses and pipes fit tightly in the valve covers and valley cover and take it from there. Make sure the PCV hose from the valley cover can't suck shut in any running situation. I like to use the very stiff power steering return hose for this purpose. Hope your engine is OK.

[gto19]

Thanks for the reply. It’s only pings when I step on it it . I will back off the timing a little today . Car doesn’t smoke at all and runs great .

["QUICK-SILVER"]

Using the (R+M)/2 these engines would need something like 95 octane to run factory tuning specs. With 91 you've got the high cylinder pressure happening too soon. That could very well be the source/reason/cause of your excess blow-by.

Clay

[gto19]

Thank you clay

I’m no mechanic by any means but I can hook up a timing light and back off the timing a tad

Originally Posted by "QUICK-SILVER"

Using the (R+M)/2 these engines would need something like 95 octane to run factory tuning specs. With 91 you've got the high cylinder pressure happening too soon. That could very well be the source/reason/cause of your excess blow-by.

Clay

[coonhunter70]

The pinging sound is bad stuff

[gto19]

When you time a 67 gto do you plug the vacuum advance On the distributor and also plug the carburetor port where the line from the vacuum advance goes into ?

[Kenth]

Originally Posted by gto19

When you time a 67 gto do you plug the vacuum advance On the distributor and also plug the carburetor port where the line from the vacuum advance goes into ?

Yes.

["QUICK-SILVER"]

Just stop the vacuum leak if there is any.

Plug the hose where it comes off the distributor or pull the hose off the carburetor and plug the nipple.

The vac can itself doesn't have to be plugged.

Clay

[gto19]

Ok
So I borrowed my buddies snap on old school timing light and also his snap on tach dwell meter and did some tests. Timing is at 6 ,total timing was at around 32-34 . This with the vacuum advance plugged and the carburetor port plugged.dwell I set at 30 . Idle at 700 .New cap ,rotor ,plugs ...waiting for spark plug wires from Ames .running nice and smooth . Super fast . Burns tires for days . No pinging but it is cooler this morning if that makes a difference. No smoke out of tail pipes .at idle some smoke and oil comes from the oil original breather on the valve cover. But damn she runs strong . I will have my mechanic check compression and leak down in the next couple weeks just to be sure .

[aceaceca]

In my instance, it was a broken piston from detonation.

[GT182]

Sounds like bad rings. Don't ask me how I know.