Blow By on a fresh rebuild. Possible ?? PLEASE HELP. Pics inside

A week ago or so I posted a thread in regards to my car smoking a little bit. I thought It might have been running to rich so I adjusted the fuel mixture screws with no success. Well yesterday I took her out for a drive and I noticed there was oil coming from the passenger exhaust pipe. My heart sank !.....First thing that came to mind was a blown piston rings... I looked under the hood and noticed there was black residue coming out of the #2 cylinder. I had actually noticed this 2 weeks ago but figured it might be normal b/c the header bolt was a bit loose on the # 2 exhaust manifold...

So I spent half the night searching the forum and reading up on other articles. Seems like there are other possibilities than just blown piston rings. For example, one member stated that he experienced the same problem just after replacing his valve covers for some chrome Holley's. He didn't replace the PCV valve and he was experiencing "blow by". Another member had bad valve seals.

So here I am wondering what the worst case scenario is.....

Specs:
SBC 350 rebuilt winter of 06'
Installed July 08'
Running synthetic oil

When I installed the motor it never showed any signs of smoking. In fact, I would drive the car up and down my alley with open headers and it never smoked....It started smoking only after I had the full exhaust done (3 weeks ago) and I installed some Edelbrock Elite valve covers. I didn't replace the PCV valve. During this time I also attached the tranny vacuum line and tinkered with the timing.


Pics:







Register now (free) or login to remove ads

How hard would it be to do a compression and leak down test ? Could I get the necessary tools at Autozone or NAPA ?

I'm going to pull the plugs on all 8 cylinders to see how they look....

...What gets me is that the car starts up fine, idles good, throttle response is good, oil pressure seams to be good except that I did have to add about a quart yesterday..

Do you have the baffels in place in the valve covers? Also are they 'short', or 'tall' valve covers?

The valve covers are Edelbrocks Elite Series...Cant remember if the inside of the valve covers had baffles.....

Pull your pcv hose off, and replace it with a lenght of clear plastic hose. Start it up, and watch for any oil being sucked through it. This will let you know if there is a baffle missing.

Will do this as soon as I get home....

So if it sucks oil, then the baffle is missing? And if this is the case, what can I do to fix it?... would this cause oil to shoot out the #2 cylinder exhaust port ?

It will cause it to come out of any cylinder. If it is just #2 shoot some carb spray into the pcv hole, with the valve removed. If the idle picks up, your intake gasket could be bad.

interesting...

Let me see if I got this right: If the PCV valve is bad or there is a baffle missing, oil is sucked up through the hose, into the rear carb vacuum port and out of any random cylinder exhaust port ?

As for your second suggestion. I shoot carb spray into the pcv hose (carb side) and not the actual valve cover right?

No shoot it into the valve cover to test the intake gasket.

The clear hose is an excellent idea for checking the baffle in the cover.

I also had the same problem with #2 on my most recent engine. PCV on a qjet is in the front and even though it's centered and supposed to feed the entire plenum, it somehow feeds most of the oil into #2 cylinder. I was sucking about a quart every 300 miles!! I have tall Proform covers with what I thought was a pretty good baffle. Not quite true. What I ended up doing was very simple and fixed the problem almost 100%. I put two 0-rings around the PCV valve to space it up from the bottom of the baffle. Mine was sitting ON the baffle and sucking any oil that came it's way.

I also have an oil separator in my PCV hose. It helps but did NOT trap all the oil that was going through it. Maybe it's kinda hoky but it now has over 1/2 quart in it that was filtered out of the PCV line from just normal blow by.

Mark

gotcha...

How will the carb spray help detect if the intake gasket is bad? I know it will increase idle as you mentioned it might do, but I'm curious to see why the idle would increase by simply spraying it into the valve covers.



sorry for the hundred questions fellas.

I used the clear hose to find a massive oil consumption problem in the blown engine in my avatar. All I had to do was put a tall set of valve covers on it to fix it.

JMark, when you say that the PCV on a Qjet is in the front, do you mean the vacuum port ?

My PCV hose runs to the back of the QJet on the distributor side....

Thank you for taking the time to walk me through this. I'm gonna try your techniques when I get home. I'm just praying it's something simple and not bad piston rings....