Lots of good info here and some very good diagnostics info. Here’s a little more. If the carb is running too rich it can wash out the rings on a new engine. Also, here is some old school stuff. If you’re burning oil, have somebody drive behind you. Get to a good cruising speed. Jump on the car and if it smokes while accelerating it could be rings if it smokes when you back off a the hard acceleration could be your valve seals.
Oil on sparkplug threads
- Thread starter jondebo
- Start date
sandlapper
Veteran Member
Agreed; Very True. And neither do any aftermarket performance heads I'm aware of.
*But every OE production sbc well into 80's & if not newer Does have O-ring valve seals.
OE production Iron L30 & L31 Vortec heads do not have O-rings but instead employ much more effective positive seals mounted atop guide bosses which are OE machined to fit posi seals.
My experience has shown those newer positive seals are more forgiving and remain effective even when guides become worn and valve stems stems looser fitting; their rubber compounds are also more resistant to heat and embrittlement. A softer posi seal is more able to conform (stretch) and accommodate stem side-to-side wiggle as guides wear.
SBC has evolved, and in toto, for the better.
However, if you're stuck with O-rings that need replacement, but you're not up for some of the various means to retrofit Other type stem seals; then it is what it is. Not a new dilemma.
Another quick way to check for leaking valve seals (usually because of worn guides, but could also be old brittle seals), let the car warm up and idle for about 5-10 min, then romp the throttle once. If you get blue smoke out the exhaust, that means the chambers were loading up with oil.
Also, after driving the car, and no blue smokes is coming out, park it and let it sit overnight. If when you start it, there’s a puff of blue smoke, then that was Oil from the heads leaking down the valves into the chambers too.
Blue smoke is oil, black smoke is fuel and white smoke (usually smelling sweet) is coolant (assuming you’re running anti-freeze.
Also, very common problem on rebuilt engines (especially rebuilt with milled decks/heads) is the intake doesn’t seal on the bottom edge of the ports and sucks oil into the intake ports from the lifter valley. There were some good articles in car craft years ago talking about using small lead shot (compressible; probably could also use soft solder pieces) at the four corners of the intake with a new intake gasket to see how far the top vs bottom conpresses. I know my engine had this issue. You’ll see oil on the intake ports of this is an issue.
Also, after driving the car, and no blue smokes is coming out, park it and let it sit overnight. If when you start it, there’s a puff of blue smoke, then that was Oil from the heads leaking down the valves into the chambers too.
Blue smoke is oil, black smoke is fuel and white smoke (usually smelling sweet) is coolant (assuming you’re running anti-freeze.
Also, very common problem on rebuilt engines (especially rebuilt with milled decks/heads) is the intake doesn’t seal on the bottom edge of the ports and sucks oil into the intake ports from the lifter valley. There were some good articles in car craft years ago talking about using small lead shot (compressible; probably could also use soft solder pieces) at the four corners of the intake with a new intake gasket to see how far the top vs bottom conpresses. I know my engine had this issue. You’ll see oil on the intake ports of this is an issue.
Bandit723
Veteran Member
so what intake gasket is used with milled/decked heads? i see that felpro does have a fatter one.
Bandit723
Veteran Member
sure is...
jondebo
Veteran Member
Money hasn't been great, so my focus has been elsewhere. Some context: the car is currently stored in a less than ideal situation and it makes it hard to work on. Anyway, got a hold of a leak down test kit from Napa. Piece of crap but got it to work. Found that the cylinders are all leaking 8-15%. Found no other leaks. Other posters have mentioned how bad the plugs look. Agreed. Thinking back, these are the original plugs I started the engine with from new. I estimate the engine has avout 3000 miles on it. More than enough to do plenty of damage. Initial starting and break in of the motor was not done by me. An older gentlemen that used to race with my dad had the car and started it/broke it in. All he does is 1000 hp motors so I assumed he knew what he was doing. Bad camaro owner. Had a demon carb on there when I started the car. Timing initially wasn't great and I had some loose roller rockers. Pulled the cam back out and verified no flattened lobes. Checked the valve train at the time and found no damage. Bought a holley that was built by a company called SMI. 4150 with mechanical secondaries and an electric choke. Vacuum matched to the cam. Short block internals unknown, built by an acquaintance back in the 90's, he said of "quality parts." Knowing the person as I did, I took him at his word but who knows. He was building it for his 1970 camaro before his untimely demise. Heads are Dart Iron Eagle. He apparently had done work to them. I'm not currently set up to take the car further apart. No bench or work space and I live in a pretty harsh climate where working outside isn't great. Getting ready to move far away soon so I want to keep the car in one piece. Possible the car may just be stored indefinitely soon. : (
