So i am considering stepping up a couple jet sizes in my 570 holley SA and decided i would pull the plugs to see how i was running. What i found was pretty bewildering. these plugs have been in for quite a while, over 3 months at least

Plug #1 (pictured below): oil soaked around threads, and a tan color




Plug #2: spotless, looked brand new

Plug #3: white as a piece of classroom chalk

Plug #4: white as a piece of classroom chalk

Plugs#5-8: spotless, looked brand new

What im wondering is, are cylinders 3 & 4 somehow linked when it comes to getting fuel? They are the only 2 plugs that are not perfectly clean (aside from #1 which has always been a problem child).

If it makes any difference, when we did a compression test a couple months ago, all cylinders were in the 140 range while # 4 was around 120.

so whats going on with these #3 and #4????

thanks in advance

-jon

 

#1 is either burning oil or you've got a vc gasket leak. Since the plug is a little more tan, I'd say it's probably burning oil.

#'s 3 and 4 aren't linked in the intake, but it's possible you have a vacuum leak at the intake gasket over there. Spray some brakleen around that area and see if the rpm's jump up.

btw, figure out what's going on Friday.

 

this burning oil idea would make sense, seeing as i am putting a quart in every 2-3 weeks with no leaks under the car. how does one remedy this wonderful situation?

and i shall go do the old flammable liquid spray tomorrow morning and report my findings, lol.

 

Since the #1 cylinder isn't the one with lower compression, I'd guess that the valve seals are probably old and brittle. The fix is to replace the valve seals, but that's kind of a PITA with the heads on the car unless you have a compressed air source to hold the valves open.

 

is there white smoke coming out of the exhaust? That's another sign of burning oil, but if it's not a severe enough problem then there probably isn't any smoke.

to fix an oil burning problem the piston rings would need to be replaced, right? maybe a slightly thicker oil will help it from getting past the rings, but I'm not the best with this stuff, gonna need Tad's opinion or someone else's.

oh and SLO dominates this thread (even though i'm in the LBC right now )

 

the central coast is where its at. nobody can touch our weather right now, or any time of the year for that matter.

 

Blue smoke is oil.

Old, brittle valve seals would allow excess oil to drip down the valves and find its way into the chambers. Bad rings would burn oil too, but his compression readings are mostly good so I suspect the valve seals would be more likely.

 

Just since it was mentioned as a possible cause....

My 200 inline-6 had some fouled plugs on all cylinders. I am getting the head rebuilt, so we removed the old valve seals to find they were worn out, split, and could be crushed in your hand very easily. It could mean they were leaking or about to leak.

 

#1 is either running too rich(in which case you'd most likely have the other cylinder primarily fed by the same barrel showing signs of being rich), burning oil or has weak ignition. It shouldn't be tan like that, the electrode loose a little worn for only 3 months and it has heavy deposits. Are you sure it's the same heat range as the other plugs? At the very least you have a valve cover gasket leaking around there, but probably burning some oil.

 

woops, I even googled it to be sure, but apparently google fails as well

so blue = oil, white = coolant?, and black=running rich