Oil on sparkplug threads

sandlapper

Veteran Member
Oct 9, 2020
2,550
SE CSA
visually
first, pull the springs off and visually inspect that all seals are in place and not torn, split or brittle or otherwise damaged.
 

jondebo

Veteran Member
Jul 27, 2010
182
Hayward, CA
^^^this^^^
BUT --- both worn out OR Broken rings

first do the cranking compression test DRY & record pressures.
then do a WET test --- put about 5 cc (1 teaspoon) motor oil into sp hole and repeat above test and record pressures.
compare the two data sets.

experienced pro builder or not, eveyone's capable of mistakes.
it's all too easy to mistakenly lay out the ringpaks improperly when setting up for a build.
If the Second rings are installed upside-down, they will pump oil UP instead of scrape it down (by convention, Seconds have a tapered profile). Verification requires complete motor disassembly for visual inspection of rings.
Complete disassembly makes me sad. Only took me 20 years to get the engine in. 3k miles.
 

jondebo

Veteran Member
Jul 27, 2010
182
Hayward, CA
sorry pal --- let's hope you get away with simply tightening a dozen intake bolts.🙏
It's all part of hot rodding, or so they say. I'm rather liking the comment above about the oil will seal the bad rings of course : )

If anything, I'll learn more about the gen 1 sbc.
 

sandlapper

Veteran Member
Oct 9, 2020
2,550
SE CSA
using some oil to seal rings is only for test purposes.
And it is a handy way to help discriminate between a valve that's leaking COMPRESSION --- and RINGS that are leaking COMPRESSION.
The addition of a little oil will Not help seal a valve-seat that leaks compression but will help seal a ring that's leaking compression.
 

2ndGenCrazy

Veteran Member
Aug 18, 2011
1,167
Upstate New York
I don't see oil on the internal part of the plug/electrode/ground strap.
Have you tuned this to optimize spark timing and carb settings?
If the engine is not stock, you should be careful when selecting the PCV.
 

Coadster32

Veteran Member
Lifetime Gold Member
Oct 2, 2013
2,447
Milford,CT
I did a leakdown test over the winter on my Camaro. It will give you an idea if it is the rings or valves where your potential problem may lie. You can feel/hear where the leak is coming from.
I spoke with the engine builder who redid my heads a couple of years back, and he believes in the compression test over leak-down. I had one cylinder lower than the others, but still in spec. He said "romp" on the engine, as the rings may just be lined up letting more go by.

If you have double springs on your valves, you may not be able to see the valve seals. If you have single springs, then you should be able to see them. Either way, easy to take off the valve covers.

I agree with Biker, and not overlook the PCV system. As much as I tried to avoid it, I pulled the trigger on the Wagner adjustable one. The guy was great over the phone for certain. Blowby, if not accounted for, can pretty much push oil past any/all seals, past rings, and get to your plugs. If your heat range, carb, timing, setup, etc. is proper, then it may only get oil on the threads of the plug.
 

jondebo

Veteran Member
Jul 27, 2010
182
Hayward, CA
Improperly baffled PCV or the wrong PCV valve can huff in a shocking amount of oil, and soak the plugs.
Even with a baffle, I needed a catch can on mine. Instantly stopped fouled plugs and oil consumption.
I know nothing about PCV so I'll look into this.
 
Top