Thread: 396 oil problem.

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I have a 396 that is sucking oil in the intake from the valley area. It is a fresh rebuild and i have pulled the intake three time with different gaskets each time. I even used wax wire to check the angle of the intake to the h e ad. .i did have to sand the in intake to fit. I now have a very even crush on the felpro gaskets . I put it all back together and test drove it 30 miles. It was still burning oil. I pulled the intake again and the is oil in the intake runners . What the hell us going on. Bad intake. Bad heads any in put would be great

Intake valve stem clearance and seals????

Wax wire, is that plastiguage you're referring to?

Not familiar with 396 cylinder head architecture, but is it possible that one or more of the rocker arm studs is threaded into the intake ports and there is oil coming into the ports from the top side, past the stud threads? I'm thinkin' that if a previous owner tossed the pressed-in studs for screw-ins, he would could have drilled through the top of the port roof before threading the hole for screw-in rocker studs. Then, if he didn't seal the threads or even if he did and the sealant has grown old and cracked out of there, that could be the problem, couldn't it?
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Heads have a fresh valve job, yes its plastigauge. the heads are 781 casting 454 heads and do not ever remember big block heads have holes going through to the intake ports but i will look

the above picture is after a 15 mile drive and the engine was sitting 2 hours before i pulled the intake. 2,4,6,8 all look like this and 1,3,5,and 7 look about 2/3 less oil .

How about my question about valve/guide condition and clearance plus what kind of valve stem seals??????????

it has pc seals and I had pulled two springs off the head to check spring pressure and retainer clearence before i installed the new cam. I cant imagine a fresh valve job have worn out guides enough to suck in that much oil. I did borrow a an intake from a friend last night and set it on the block without gaskets. The original performer rpm would not sit flat in the valley but the second intake does and all the bolt holes line up where the first one not so good. I am not sure but I bolted the new intake on which is an edelbrock c396. I will fire it up tonight and see what happens.

PCV valve stuck open?

not the pcv

Originally Posted by 70chevybb

I will fire it up tonight and see what happens.

Soooo, what happened?

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I installed the intake and had to re tune the carb. it would not even idle how it was before so it must of had a large vacuum leak. it is still smoking a little but not sure how long it will take to burn off the oil residue that is built up on the valves and pistons. i do have to say they are coated. The only real way to tell will be to pull the intake and I will do that but not til next week. leaving on a fishing trip tomorrow. I did call edelbrock and they offered up a family and friends discount to replace the intake at 211.56 plus shipping. great offer but the local speed shop has them for 239.99. So i will post the official report in a week when i get back

The problem found. I pulled the engine and found the dumba@$es overlapped the expander rings on all cylinders. That does explain 2.5 qts of oil ever 100 miles

Glad you figured it out, sorry you had to go so far down into it..

But you should be in good shape now I hope.?.? It didn't hurt anything did it?

No other real problems found. I did buy new pistons to increase compression to just shy of 10 to 1. I also bought a comp cams 292 magnum. Pistons and rod will be done tuesday and will have it running for a saturday car show.