OK, to refresh my 73 390 with less than 3000 on the rebuild is smoking ou the drivers side only. Both sides were smoking badly before the rebuild. Compression is good. Pulled the manifold and resealed. Same thing. Pulled the manifold again and cheked over everything I could think of. This time did not use the end seals on the manifold just silicone. Manifold sits up pretty high from the valley and you can notice it rock a little when you sit it on dry. Gap at the bottom of the manifold is barely noticeably more than at the top between the heads. When the heads were done they only had a few thousandths off to clean them up. Don't know if they had more off by previous owner. Siliconed the begeebers out of it especially on the lower part of the manifold. Started it up a and no smoke until temp got to operating range and revved engine a little. NOw it's smoking just like before out the drivers side. After it's driven a little the threads on all the drivers side plugs have oil in them when removed and the # 8 plug eventually fouls with oil. I'm out of ideas. Would it change anything if I turned around the pcv to suck the opposite way? Could the angle of the manifold need machining?(remember I really layed on the silicone) Is ther something in a head that could do this? Sorry for the length of this but I/m really in need of help here and wanted to explain it as best I could.

 

There's a couple things it could be, excuse me for being a little whacky...

1) Cracked head, the oil feed for the rocker arms is leaking into an intake port. But that would really foul only one cylinder, not all four.
2) Too much porting, leading to the same thing as #1
3) Intake manifold needs to be milled (or better yet, intake side of the heads, better to mill the heads than the intake)... When you pull the intake is there oil in the intake ports? Is there oil in the head's intake ports?
4) Cracked/leaking intake manifold, allowing oil to get into the runners - again, is there oil in the intake ports?
5) Bad head gasket, allowing oil from the oil feed hole to leak into a cylinder. What's your oil pressure?
6) Cracked block, allowing oil to get into the cylinder.

Interesting thing, the oil feed hole is near cylinder # 8, isn't it?

 

Appeared to be oil in the #8 runner. Was a little difficult to tell but that runner was definately blacker than the others but as I wiped my finger in it it did'nt appear to be very oily. There is an oil feed at the front and rear of the head just outside the water jacket. How am I going to narrow this down?

 

First off oil is fed to the heads thru one of the rocker hold down bolt holes. There are drains at each end of the head. If you are getting oil in an intake runner it is either coming from the intake to head surface gasket or the intake valve stem seal. Just isn't any other place for it to come from unless something is crack (unlikely for your problem).

 

Just a couple of trivia questions:
Did the rebuild include a high volume oil pump?
Were the heads rebuilt, including new valve guides?
What type of valve stem seals, newer positive type, or older umbrella type?
Oil restrictors before the rockers installed?

There have been a few threads about the valve covers filling with oil, it pumps in faster than it can drain. Umbrella type seals can't stop oil under this condition. This was a new one to me, learned of it here. It's kind of coincedental that the worst cylinder is next to the rear drain. Also, if there is enough wear between the valve stem and guide, nothing will stop oil.

Just some food for thought.

 

Yes a new melling pump was installed. The heads had new guides with umbrella seals. Used the #90 Holley jets for restrictors.