[1973ramairman]

Engine runs rough, pulled plugs and 3 plugs on the right bank of cylinders where normal but one was completely fouled and two plugs on the left bank same thing .possiable problems ?

[77 Canamman]

Oil control? Is it using oil between changes? If it is, could be valve seals/guides, PCV valve, or oil rings.

[1973ramairman]

Yes it does use some oil , but not a lot. When I go I wide open it will blow a bit of smoke , but only for a few seconds than clears. Heads wher completely rebuilt ( for what it's worth ) although stuff still happens.

[1973ramairman]

Could this also be a bad cam lobe issue?

[gary bennett]

just a question but are you using the correct plugs for that motor?

[gtohurstjudge]

That is oil foul.........time to tear into the engine.

[64CatalinaVentura]

My car does this because the bottom end of the engine has never been rebuilt and after over 100k miles the cylinder walls are worn. I change the PCV frequently, run 15-50 oil, and have oil fouling of my plugs every 2500 miles. This was only a little problem until my heads were rebuilt as part of a larger issue, which resulted in returning the car to higher compression. I don't do cross country trips so l just monitor everything like a hawk knowing it will need a full engine rebuild sooner rather than later.


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[Lightfoot]

I had that exact symptom with a tired Chevy V-6.
The solution was to remove the valve cover and clean all the GUNK out of the oil drainback passages. This was an '80 Lemans that I bought for $400 for driving back and forth to work. It smoked all the time and would foul the no. 6 plug periodically.
When I finally got the ambition to pull the valve cover, there was a great deal of sludge in there. Took me all afternoon to clean it up, and had to wait till the following weekend to do the other side.
Never saw anymore smoke or fouled another plug after I was done. (35,000 miles additional)

[Lightfoot]

Originally Posted by 1973ramairman

When I go I wide open it will blow a bit of smoke , but only for a few seconds than clears.

This sounds like a classic indication of excessive valve guide clearance.

[Heybuck]

I'd be doing a leak down test before laying any spanners on it. Easy to do and very informative.

Remember, while its still running, it's talking to you. Get the spanners out and it stops talking.

[GT182]

What brand of oil do you use Lightfoot? I've seen that happen with most brand names and also from changing brands or mixing them. I used to do that a long time ago and always had a sludge issue.

I've never had a problem using Valvoline, and I stick with it no matter what or the cost. I've been using Valvoline 20W-50 for 9 years in my GTO and have had no problems at all. My engine builder said to us it and it's never seen anything else.

[U47]

Heads recently rebuilt, 3 plugs on rt. bank ok one n/g and 2 plugs on the left bank OK and 2 n/g

I would get a compression and if that's OK I would check those valve guide seals.

[1973ramairman]

Plugs are A/C delco R45TS , 40 gap , oil is Joe Gibbs 10W30. Approx 800-1,000 miles since rebuilt. Setup timing and carb idle screws today to get running better, timing is 14 degrees initial idling at 1,000, vacuum 17-19 Hg at idle and 25 Hg at 2,500 rpm. Vacuum is stead at 2,500 but jumps back and forth quickly at idle between 17-19 Hg. Cam is a Lunati voodo 268/276 advertised, 227/233 duration at .050, LSA 110/106.. Carb is a factory Rochester ,Can't get the idle any lower backed idle screw right out , but idle will drop to 800 if I lean out the idle screws , but than I get back firing thru the exhaust

[lust4speed]

Considering the severity of the build-up, I'm wondering if those plugs are firing consistently? Are the spark plug wires fairly new and in good shape? If you have a timing light that clamps on the spark plug wire, go from wire to wire at idle and see if you get a consistent flash on all wires with the clamp as close to the plug as possible. All you are checking for is a uniform flash. You will need clean plugs to pull this off because a shorted plug won't flash the timing light. This just might expose another underlying problem other than oil consumption.