Spark Plug Diagnosis

[Gerard F.]

Re: Spark Plug Diagnosis

Mike,

Your plan sounds like a good one. Before changing the #8 plug wire, run it for a 100 miles, then pull the plugs and see what they look like.

If they are all seemingly fouled and black with oil, maybe the problem is with the valve seals. If the #8 shows up black and the others are OK, then maybe it is the plug wire or the valve seal on that cylinder.

Yoru report of an increase of oil consumption to a quart 500-600 miles sounds like an oil problem may be the root of it.

Have fun, it is all fun with these cars

[Joe C.]

Re: Spark Plug Diagnosis

Wow, what a great series of input. Thanks to all.

Let me try and address a few questions raised. Joe asked how "tarr'd" the engine is. It is the original engine but the original owner had it rebuilt in 1990. When I bought it in 96 it had 780 miles on the rebuild. The only thing I really know about the rebuild is that they supposedly put a bit of a performance cam in it. The idle and vacuum seem to support that. I have driven it pretty regularly since then and put nearly 40,000 miles on it. It has always used about a quart of oil every 700 to 800 miles, although it's recently increased consumption to a quart every 500 to 600 miles.

To answer some of the other questions, the tune up I did last year before our 5200 mile adventure included plugs, points, condenser, rotor, cap and plug wires. The plugs installed at that time were the AC44 in the pictures. This year's tuneup included all of the items above except for plug wires. I also went with the Champion RJ14YC (AC45 equivalent) and am very happy with the results. Of course, based on what I pulled out, it had to be better!

Joe asked for some better pics on the spark plugs so here they are:
[ATTACH]17709[/ATTACH]

[ATTACH]17710[/ATTACH]

[ATTACH]17711[/ATTACH]

[ATTACH]17712[/ATTACH]
There is an awful lot of carbon although this view of #8 doesn't show the big chunk that you saw in the earlier pic. It is still there. Joe or others, any other thoughts on what you see here?

The comments on exhaust leak on the passenger side make some sense. Last June I removed the driver side exhaust manifold to have a flange fixed with spray weld. It was reinstalled (w/o gaskets) but it had two good clean surfaces and it appears to be sealing well. I did not remove the passenger side manifold, just retorqued it. I did remove the AIR tubes on both sides and installed plugs which made a big difference. The AIR tubes were leaking and I had all sorts of exhaust leaks.

Based on all of the inputs, I'm going take the following line of action:

• Replace the #8 spark plug wire, just in case.
• Check the torque on the passenger side exhaust manifold. Also check for leaks.
• Run through the timing to see if I'm getting enough advance from the vacuum advance. I’ve often thought it would benefit from a little more advance at idle. I’ll use John Hinckley’s Corvette Enthusiast article from 2003 as my guide for this.
• Adjust the carburetor to "lean" it out a little bit.
• Continue to monitor oil consumption.
• Next tune up I may opt for the AC Rapid Fire’s that Bill C recommends. I may also move to the Pertronix electronic ignition so many have recommended… but that’s next year.

Thanks again for the advice. Keep it coming. It really is great fun learning and doing.

Mike,

Those plugs are oil fouled.

Based on your oil consumption, you should perform a leak-down test on the engine.

The leak-down test might not give conclusive results, in which case, the valve guides/seals are suspect.

It depends on what you intend to do here. You can drive it like that for a long time by installing "oil plugs", adding a quart every 500 miles, and cleaning the carbon from the chambers by lightly drizzling water down the carburetor on a hot engine while throttling up to about 2500 RPM. Add just enough water until just before the engine wants to cut-out. This process will cause a lot of steam/smoke/debris out the tailpipes, so don't be alarmed. Do this for a "good" 5 minutes or so. If you leave all of the crap in the chambers, as it breaks off, it will cause intermittent shorting of your plugs, which may or may not be apparent to you. In most cases, if the frequency of the intermittent short becomes high enough, the plug will finally become "dead" because it will never have a chance to clean itself by getting up to proper temperature.

Try this test. I'm willing to bet that you'll see billows of white-blue smoke out the tailpipes: With engine at op temp, in second or third gear, get the R's up to about 5000 and abruptly close the throttle, check your mirrors and note which side(s) the smoke is coming from.

You should be able to hear the exhaust leak on the right side.

Joe

[Michael A.]

Re: Spark Plug Diagnosis

Joe
Thanks for the suggestions. What's the likelihood that the oil is coming up past the rings vs. down the valves? Is there a way for me to test to determine which is the sources?

In the meantime, the car is running well. Other than the nuisance of the added oil, am I risking much by driving it this summer. I usually put on 2 - 3000 miles. I will give your "water" remedy a test this weekend. Hope it doesn't get me sent to Guantanomo.

Cheers
Mike

[Joe C.]

Re: Spark Plug Diagnosis

Joe
Thanks for the suggestions. What's the likelihood that the oil is coming up past the rings vs. down the valves? Is there a way for me to test to determine which is the sources?

In the meantime, the car is running well. Other than the nuisance of the added oil, am I risking much by driving it this summer. I usually put on 2 - 3000 miles. I will give your "water" remedy a test this weekend. Hope it doesn't get me sent to Guantanomo.

Cheers
Mike

Mike,

Good.......and don't forget to treat both sides of the primary intake runners with equal amounts of water.
If a leak-down test shows minimal to zero leakage past the rings, intake valves, and exhaust valves, then that would indicate that your valve guides and/or seals are worn. A leak-down test showing minimal leakage past the rings will NOT tell you whether or not you have any broken or seized 2nd rings or oil scraper rings.

No.........you are not risking anything by driving it the way it is. It will very likely run "good" until the situation reaches the point where the intermittent shorting of the plugs in the suspect cylinders reaches the point where the plugs no longer self clean. At that point, you'll need to install special "oil plugs". In the meantime, if you decide to change the plugs rather than simply clean them, replace with a set of R45 or equivalent. The cleanout of the carbon will simply prolong the inevitable, and will decrease the frequency of misfiring. It will also remove any hot spots in the chambers which MIGHT be causing incipient detonation.

[Duke W.]

Re: Spark Plug Diagnosis

The level of oil consumption you are experiencing is merely a nuissance. As long as the engine has good power and response (okay readings on a leak down or compression test) you need do nothing, but replacing the valve seals, which is not that hard/expensive a job is probably worth it as this may reduce the oil consumption.

Since your engine has be rebuilt, who knows what you'll find in terms of guides/seals unless you have documentation on what was done. Once the springs are off you can check for guide wear and go from there.

I'm not a fan of dumping water down the carburator - best leave that to bubba. Combustion chamber deposits won't usually do harm, but too much water can cause hydraulic lockup and a bent rod.

As a reference point my Cosworth Vega always consumed a lot of oil. I finally decided to replace the valve seals when it got down to about 150 miles per quart (other than oil use the engine ran very well), but then I discovered signficant valve guide wear, so it was off with the head for a refresh - new guides and a better than OE quality valve seals.

The high rate of oil consumption built up a lot of white/tan deposits on the spark plugs, which is oil additive ash, but it never misfired or otherwise misbehaved because the HEI can blast a spark through nearly anything.

The single point ignition has only half the energy of the HEI, so high oil consumption may cause misfires and black carbon deposits rather than white ash deposits.

Make sure your ignition system is in tip-top shape including plug wire resistance, which should be no more than 5000 ohms/foot.

Duke

[Jean C.]

Re: Spark Plug Diagnosis

Mike, of the 4,059 folks who are registered on the TDB, you will likely get that many suggestions on spark plug wires so here's mine. I use Pertonix wires now that I no longer have the car judged. The car runs smoother when accelerating than it did with the correct date repop wires I previously used. Just my 2 cents worth based solely on personal experience (no animals were injured in this less-than-scientific evaluation).

Best regards,

[Joe C.]

Re: Spark Plug Diagnosis

The level of oil consumption you are experiencing is merely a nuissance. As long as the engine has good power and response (okay readings on a leak down or compression test) you need do nothing, but replacing the valve seals, which is not that hard/expensive a job is probably worth it as this may reduce the oil consumption.

Since your engine has be rebuilt, who knows what you'll find in terms of guides/seals unless you have documentation on what was done. Once the springs are off you can check for guide wear and go from there.

I'm not a fan of dumping water down the carburator - best leave that to bubba. Combustion chamber deposits won't usually do harm, but too much water can cause hydraulic lockup and a bent rod.

As a reference point my Cosworth Vega always consumed a lot of oil. I finally decided to replace the valve seals when it got down to about 150 miles per quart (other than oil use the engine ran very well), but then I discovered signficant valve guide wear, so it was off with the head for a refresh - new guides and a better than OE quality valve seals.

The high rate of oil consumption built up a lot of white/tan deposits on the spark plugs, which is oil additive ash, but it never misfired or otherwise misbehaved because the HEI can blast a spark through nearly anything.

The single point ignition has only half the energy of the HEI, so high oil consumption may cause misfires and black carbon deposits rather than white ash deposits.

Make sure your ignition system is in tip-top shape including plug wire resistance, which should be no more than 5000 ohms/foot.

Duke

That's MISTER bubba to you.

[Michael A.]

Re: Spark Plug Diagnosis

That's MISTER bubba to you.

To "bubba" or not to "bubba". That is the question.

[Gerard F.]

Re: Spark Plug Diagnosis

Whether 'tis nobler in the mind to suffer
The slings and arrows of an outrageous cam,
Or to take arms against a sea of oil troubles.

How's your new cam, Mister Bubba.

You M.E.s ought to be a little more Civil.

[Michael A.]

Re: Spark Plug Diagnosis

Whether 'tis nobler in the mind to suffer
The slings and arrows of an outrageous cam,
Or to take arms against a sea of oil troubles.

How's your new cam, Mister Bubba.

You M.E.s ought to be a little more Civil.

The Bard lives! He has just moved to a more hospitable climate and appreciates vinyl tops.

[Joe C.]

Re: Spark Plug Diagnosis

Whether 'tis nobler in the mind to suffer
The slings and arrows of an outrageous cam,
Or to take arms against a sea of oil troubles.

How's your new cam, Mister Bubba.

You M.E.s ought to be a little more Civil.

Now THAT'S funy!
Do you remember Mister Bubble?

http://www.youtube.com/watch?v=PmUnqrZI4qE

..... And by responding, holeshot them. To speedshift, to powerbrake;
No more; and by a trap speed record to say we end
The bellhousing and the thousand natural shock absorbers....

[Joe C.]

Re: Spark Plug Diagnosis

To "bubba" or not to "bubba". That is the question.

Michael,
What have you got to lose? If you break something, you can then install an LT1 cam and a set of Crower rods. Just wear a helmet, full face protection, and fire suit while pouring the H2O. Anyways, you should click on my signature link before.............

Seriously, the "waterboarding" is a band-aid.
I have done it many times before.
It works, but the real solution is to fix the problem.
Only..............don't use SeaFoam.
Looky here:

https://www.forums.ncrs.org/showthre...water&uid=3847
and here:

https://www.forums.ncrs.org/showthre...water&uid=3703

[Michael A.]

Re: Spark Plug Diagnosis

[quote=Joe Ciaravino (32899);415609]Now THAT'S funy!
Do you remember Mister Bubble?

http://www.youtube.com/watch?v=PmUnqrZI4qE

I think I just experienced an acid flashback. I haven't seen that for over 40 years but I remember it like it was yesterday. What a hoot.

[Michael H.]

Re: Spark Plug Diagnosis

[quote=Michael Andresen (27410);415773]

Now THAT'S funy!
Do you remember Mister Bubble?

http://www.youtube.com/watch?v=PmUnqrZI4qE

I think I just experienced an acid flashback. I haven't seen that for over 40 years but I remember it like it was yesterday. What a hoot.

It's called "Mr Housing Bubble" today.

[Joe C.]

Re: Spark Plug Diagnosis

[quote=Michael Hanson (4067);415778]

It's called "Mr Housing Bubble" today.

Every time I think about what the real estate and stock markets have turned into, what with the prevalent greed, manipulation, fraud, and for the last thirty years, wildly fluctuating boom/bust cycles, I make a simple analogy to that old kid's game of musical chairs..................it's all fine and dandy as long as the music is playing, but woe to the one who is left standing when it stops.

What ever happened to the good old days (1940's thru 70's) when the stock market and real estate markets were much more stable...........a decent home cost less than $30,000.00 and appreciated at a snail's pace every year, but appreciated always. The Dow was less than 700, and steadily climbed at just over the inflation rate.

My parents bought their first home, in fall of 1953 for $13,000. I "passed" on an investment property in 1979. It as a three family all brick house in Bklyn, NY, for $79,000. Less than 10 years later, that same house was resold for over $150,000. In 2006's market, it "peaked" at just under $500,000.00. The house was built in 1951, using "common" bricks, during the building boom just after WWII...............sale price, $15,000.00.