Priya

I can't believe it but I'm stymied trying to get the spark plugs out of my 79 350. Hubby rebuilt the carburetor but its not running much better so I thought I'd check the plugs and wires but holy crap, where the hell are they?

I managed to get my left hand on the spark plug boot for the driver's side front spark plug but couldn't pull it off. Do I need to lift the car and go at it from underneath, or do some combination of underneath and on top?

Shark Racer

I usually go above and below, but I have headers. It should be a bit easier with exhaust manifolds.

If the plug boots have been on a while they could have sort of seized to the plug. Try rotating(wiggling) them. One they move in that direction they'll be a lot easier to pull out.

Man, I had some on my 2006 Avalanche that practically made me want to cry, they were so hard to remove.

Sully1882

front ones I went below on and back ones I think from the top. It helps if you have smaller hands and long arms! Just gonna have to get in there and go at it!

Sully

gcusmano74

Don't work on that engine unless it is stone cold. A hot exhaust manifold will cook the skin right off your hands.
Torque spec on a taper seat plug is not much; only about 14 lb/in. Or finger tight, plus 1/8 turn. A little dab of anti seize compound on the threads will make things easier next time.

Priya

Thanks for the suggestions. I don't really want to tell my husband I couldn't do it but I'm pretty wimpish. He'd probably say "There's a lot of quit in that girl.", Lol.

xrav22

I saw this in the c4 and had to come over. I just changed mine and this tool is the best for spark plug wires. It will twist and then you can pull real good and not hurt the boot.
I don't work for them or anything. Don't forget the dielectric grease on the boots if you need to rearrange them or anything.
http://www.ebay.com/itm/Powerbuilt-11-inch-Long-Reach-Hose-Clamp-Pliers-New-/290762602194?pt=Pliers&hash=item43b2cd36d2

Priya

So I went back and had at it again. I did like Shark Racer suggested and gave the one boot I could get my hand on a twist and it popped right off. I was expecting something like this, but I didn't think it would be this bad:



Seems to me someone on here was saying something about most carb problems being ignition problems, bahh, what does he know, lol.

The car shows 60,000 miles and judging by the interior and exterior condition its hard to believe that's not the original mileage. The owner I bought it from had receipts for a rebuilt L82 but this thing uses a litre of oil about every 700 or 800 miles and judging from the plug its hard to believe it's been rebuilt at any point, even if that was original miles and it was never rebuilt this looks pretty rough to me.

gcusmano74

Wow. That's one messy plug. Do they all look like that?
Is that oil or gas on the plug? Looks like oil from here, unfortunately.
Did that engine even run? If it's gas on the plug, maybe a bad plug/wire/distributor cap, and the cylinder wasn't even firing.
If it's oil, you might discover a leaking intake manifold gasket that allows the cylinder to suck up oil from the lifter valley.
Next probability is valve seals, then , ouch, rings.

Priya

That's the only plug I've been able to get at so far, lol.

I'm sure its oil. Yes, the motor is running albeit quite poorly. I paid $12000 for this car partly because it had receipts for a rebuilt L82 and I thought I had a solid motor. It did run pretty well at first. I was planning on putting Vortec heads and TPI on it but I'm betting all the plugs look like that and the bottom end of the motor isn't anywhere near as solid as I thought it was. Kind of hard to believe, the rest of the car is pristine, the apparently quite beat up motor is sure out of place.

TimAT

Looks like oil to me. Is it soft and gooey or hard deposits? I'd get all the plugs out and see where they are. Then a compression and leakdown test.

Priya

I don't want to mess it up before my husband looks at it so I don't want to touch it just yet.

Can a compression or leakdown test be done with the motor cold? It looks like lots of burns on the hands and arms trying to take the plugs out from a warm motor.

TimAT

Ideally, both the compression and leakdown tests should be done on a warmed up engine. But doing it cold will give good enough results you will be able to figure out what is going on. If that is in fact oil, either the plugs haven't been changed in a really long time, there's a bad plug wire and that cylinder is not firing, or the valve guides or rings are really, really tired.

Priya

So, I'm talking to hubby and he's telling me there's no point in doing a leakdown test or a compression test, that I should just put new plugs in it and see how it goes. He says because there's no baseline compression numbers just after the engine was rebuilt there's no way to know if the results we get are good or bad. He says if you get 150 all around and one cylinder is 120 then you don't know if its the valve or the rings and you can put oil in the cylinder but that isn't definitive. Or he says you get 120 compression all around and you don't know if that's good or bad so there's no point in doing it. He says its no different with a leak down test which will eliminate low readings from a weak battery or starter but its the same deal because there's no starting numbers to judge the motor by.

He says better off to put new plugs in it and see how long they take to foul and see under what circumstances it blows blue smoke and so on. Because if the valve guides are leaking you can't tell that from a compression or leakdown test.

I'm feeling a little agravated, I think if I'm going to pull all the plugs I may as well do a compression test while they're out and I think you can tell quite a bit from it.

OMF

It's a real shame your "rebuilt" engine is behaving this way. I think the first thing to do is pull the remaining plugs and check out what shape they are in. Next would be a compression check to determine what shape your ring and valve sealing components are in, then have a look and ensure you have a good spark at each plug.

With that info, we can give you a good direction to head towards...

and yes you can tell where the problem is with a compression test by listening for leaks down the carb (intake valve), down the oil fill port ( rings), or the exhaust (exhaust valve)

DC3

I think before I assumed the worse about the rebuild, I would do the opposite and assume the rebuild was good. Then start by going back to the basics and verify everything. Start with the ignition. Verify the distributor is working properly, the vacuum advance works properly, the timing is set properly, and the spark plug wires are in good shape. Change the plugs, gap them properly. Adjust the carb as necessary. Check the vacuum. Check the thermostat. Check for vacuum leaks.

Once you are sure everything is in order, drive the car and periodically check the new plugs and then report their condition so these gurus can help you with any further diagnosis. Remember, this is a 30+ year old car and even if the engine was rebuilt properly, the use of some older parts could be part of the problem. Example: When I bought my '73, the distributor was so gunked up, it could only provide 14 degrees of mechanical advance. After a dis-assembly and good cleaning, it was able to easily get 18 degrees of advance.

If it comes to a compression check, make sure to get a good compression gauge and then make sure it is sealing properly when you do the test. I did some compression checks on my '73 when I first bought it and thought I had some problem cylinders. Turned out the fitting on my new gauge was too fat and did not clear my headers well enough to be screwed in far enough to provide good sealing. My engine was fine and just needed some careful tuning.

DC

Priya

I'm not sure if I've got a compression tester, my house and garage were broken into several years ago and most everything stole. Not sure if they got the compression tester or not, haven't looked for it since then, but that's what I'm going to do, pull the rest of the plugs and depending on their condition do the compression test and go from there.

OMF

Smart move...
Just borrow a compression tester if you need to

Priya

Okay, so Hubby took pity on me and pulled the rest of the plugs for me. We found it was backwards from what Sulley1882 said, the front four plugs are (barely) accessible from up top and the back four plugs are accessible from underneath. Someone on the C4 forum told me they could do all from up top but I'd say that'd be a miracle if you could get the back four from up top. There were two other plugs looking similar to the one pictured but not quite as thick with oil and the rest had significant deposits but were running hot enough that only the inner porceline was black and the electrodes were beige.

I talked my sweety into doing a compression test and here were the results (motor was cold during test)

1) 125 lb (this is the cylinder the pictured spark plug came from)
2) 135 lb
3) 132 lb
4) 135 lb
6) 130 lb
7) 140 lb
8) 140 lb

The battery was dead when we first went into the garage but after some time on high charge had enough to crank the motor for the compression test. I think it was cranking faster towards the end of the test as the charger was still on it so perhaps that explains the 140 lb numbers. All in all I don't think those are too bad of numbers for a cold engine and no major failures are apparent although I really question the alleged rebuilt motor as those plugs all looked like they had been in there a very long time.

TimAT

Those numbers are not bad- all of them are close enough to prove there's not a cylinder laying down.
Toss a new set of plugs in there and see what you get. Maybe a set of wires just for good measure.

Priya

The new plugs are in but there's some sort of power drain that keeps killing the battery so we haven't fired it up yet.