Spark Plugs-What's wrong here

[Gerard F.]

Today is my car's 41st birthday. 6/29/67 for my 22049 67 327/300HP.

So, for her birthday, I thought I'd change the plugs. Got these NOS? (with the green bands) R-44 to replace the current R-45's which have been in about 3 years and 6000 miles.

Here's the set of eight, I took out in engine order looking forward:



Here is what the #1 plug and 6 of the others look like:

http://img530.imageshack.us/img530/1535/sparkplug1smallnr5.jpg

But here is the #3 cylinder plug:

http://img530.imageshack.us/img530/4997/sparkplug3smalldc0.jpg

Black hard deposits on it, but not fouled. I actually thought that she was running great before I saw this.

So what's wrong here?

Comments appreciated, trying to make the 500 rpm idle challenge.

Jerry Fuccillo
#42179

[Joe L.]

Re: Spark Plugs-What's wrong here

Today is my car's 41st birthday. 6/29/67 for my 22049 67 327/300HP.

So, for her birthday, I thought I'd change the plugs. Got these NOS? (with the green bands) R-44 to replace the current R-45's which have been in about 3 years and 6000 miles.

Here's the set of eight, I took out in engine order looking forward:



Here is what the #1 plug and 6 of the others look like:

http://img530.imageshack.us/img530/1535/sparkplug1smallnr5.jpg

But here is the #3 cylinder plug:

http://img530.imageshack.us/img530/4997/sparkplug3smalldc0.jpg

Black hard deposits on it, but not fouled. I actually thought that she was running great before I saw this.

So what's wrong here?

Comments appreciated, trying to make the 500 rpm idle challenge.

Jerry Fuccillo
#42179

Jerry-----


I'd say you've got an oil problem in that cylinder. Most likely, it's a valve seal and/or valve guide problem. If your valve seals have never been replaced, you're fortunate that you don't have this problem in more cylinders.

You can replace the valve seals without removing the cylinder heads. I would replace ALL the valve seals.

[Terry R.]

Re: Spark Plugs-What's wrong here

I would also check compression while I had all the spark plugs out.

[Wayne P.]

Re: Spark Plugs-What's wrong here

You'll be amazed at how much better it runs if you think it ran good this way!

[Joe C.]

Re: Spark Plugs-What's wrong here

Today is my car's 41st birthday. 6/29/67 for my 22049 67 327/300HP.

So, for her birthday, I thought I'd change the plugs. Got these NOS? (with the green bands) R-44 to replace the current R-45's which have been in about 3 years and 6000 miles.

Here's the set of eight, I took out in engine order looking forward:



Here is what the #1 plug and 6 of the others look like:

http://img530.imageshack.us/img530/1535/sparkplug1smallnr5.jpg

But here is the #3 cylinder plug:

http://img530.imageshack.us/img530/4997/sparkplug3smalldc0.jpg

Black hard deposits on it, but not fouled. I actually thought that she was running great before I saw this.

So what's wrong here?

Comments appreciated, trying to make the 500 rpm idle challenge.

Jerry Fuccillo
#42179

Hi Jerry,

Glad to see that you're back under the '67, getting dirty, and having fun.
I agree 110% with Joe, and here's just a little something extra. You may have seen lots of photos of improperly firing plugs, but I like this one best:

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

The term "oil fouled" should be replaced with "wet fouled" because the fouling appears the same, whether its unburned fuel, or oil. Your situation is of course, #2 photo.

Because the other seven plugs are burning so well, probably rules out a fuel distribution problem. I think that your engine has lotta miles, right? If not ever rebuilt, so, the original o-ring type valve seals are now rock hard. One of the #3 seals might have cracked, chipped or broken off, causing the apparent problem. Might be a good idea to check for slop in the guides while you're at it.

A better way to check whether you're pushing oil down the valve guides is to road test the car. You can do it in second or third gear, if you like. Get the car to op-temp, and cruise at about half throttle. Close the throttle and coast for a hundred feet or so while in gear, clutch engaged. Disengage the clutch, shut it off with closed throttle, while still rolling. Pull over and remove plugs. You'll probably see a few more than only #3 wet fouled.

If you wanna verify, then do a compression check of the entire left bank.

You'll need a valve spring compressor tool, which is a short bar with a slot and hole on one end. You'll also need a spark plug adaptor fitting for your air compressor, in order to pressurize each cylinder, to enable removal of the valve keepers/retainers/springs.

Supplement the old seals by installing teflon positive or umbrella style seals.

Joe

[Larry M.]

Re: Spark Plugs-What's wrong here

Jerry:

I recommend that you stay with AC R-45 or AC 45 spark plug heat range. Although AC 44 was recommended by Chevrolet for the 1967 327 engine, many folks (myself included) have found that this heat range is to cold for normal street driving. I have a 1967 327/350HP car and switched from AC 44 to AC 45 a year ago to solve a plug fouling problem. Having an oil leakage/fouling issue will just make things worse.

If you have the R-44's installed, then give them a try. But buy a set of R-45's for the next time....which may come sooner than expected.

Larry

[Duke W.]

Re: Spark Plugs-What's wrong here

It appears to be oil fouled, but the black deposits on the insulator indicate there is not enough heat in the combustion chamber to burn the deposits off the insulator - in other words, that cylinder may be misfiring. Even a severely oil fouled plug should not have wet, black deposits on the insulator if it's lighting the fire.

Before I rebuilt the cylinder head on my Cosworth Vega it was consuming a quart of oil in less than 200 miles and the plugs had lots of gray oil ash deposits on the insulators, but they were certainly not black. Of course, the CV has an HEI system, which will blow a spark through just about anything!

Check the spark plug wire resistance. It should be no more than 5000 ohms per foot. Compare all the long wires - 1, 3, 2, 4. Also, try swapping the #3 and #1 wires on the cap and plugs and see if the "problem" migrates to #1. If so, that wire is definitely bad. Also check the #3 terminal on the cap.

Duke

[Kevin M.]

Re: Spark Plugs-What's wrong here

Rebuild the whole thing Jerry, my 67 was as tired as yours ran great I thought. Here are my plugs cam and timing chain gear,who knew?

\

[Clem Z.]

Re: Spark Plugs-What's wrong here

check the plug wire with a ohm meter to make sure it has the correct resistance. if it is "open" you will have a fuel fouling problem

[Joe C.]

Re: Spark Plugs-What's wrong here

Today is my car's 41st birthday. 6/29/67 for my 22049 67 327/300HP.

So, for her birthday, I thought I'd change the plugs. Got these NOS? (with the green bands) R-44 to replace the current R-45's which have been in about 3 years and 6000 miles.

Jerry,

I know that you have a sense of humor, but you're kidding about the NOS "R44" plugs, right?
Shirley you know that the original plugs for your engine were AC "44". Non-resistor.
I told you not to call me Shirley.

Joe

[Gerard F.]

Re: Spark Plugs-What's wrong here

Joe,

My typo mistake, they were AC 44 which replaced AC 45's. Not sure why I had R in my head. Probably too much grappa.

I'm going to follow up first on that plug wire, that was my initial suspicion. Lately I have been feeling a miss at moderate accelleration. Thought it was my 16 year old clutch.

Good news today, my PSA = zero, reported as less than 0.01

Having fun now,

[Jean C.]

Re: Spark Plugs-What's wrong here

Jerry, looks like you are on the right track. When leaving Vegas following the Regional, I also experienced a slight miss or surge under moderate acceleration. Thought it as bad fuel but turned out to be a screwed up oil seal on an exhaust valve . The seal was obviously "kinked" when installed and decided to give up when I was beaucoup miles from home. I must have changed that spark plug a dozen or more times between Vegas and Houston. I could do it in my sleep with the motor hotter than blazes.
Cheers,

[Michael H.]

Re: Spark Plugs-What's wrong here

Jerry, looks like you are on the right track. When leaving Vegas following the Regional, I also experienced a slight miss or surge under moderate acceleration. Thought it as bad fuel but turned out to be a screwed up oil seal on an exhaust valve . The seal was obviously "kinked" when installed and decided to give up when I was beaucoup miles from home. I must have changed that spark plug a dozen or more times between Vegas and Houston. I could do it in my sleep with the motor hotter than blazes.
Cheers,

I agree with Charlie. A valve seal is the most likely cause. A plug wire that causes an occasional misfire probably wouldn't be the cause of the oil deposits on the plug. A bit fuel fouled, maybe, but that's oil, not fuel.

Also, the rest of the plugs look like they're performing properly so I definitely wouldn't just automatically move up to the next heat range. I think the 44's are perfect.

[Joe L.]

Re: Spark Plugs-What's wrong here

Jerry, looks like you are on the right track. When leaving Vegas following the Regional, I also experienced a slight miss or surge under moderate acceleration. Thought it as bad fuel but turned out to be a screwed up oil seal on an exhaust valve . The seal was obviously "kinked" when installed and decided to give up when I was beaucoup miles from home. I must have changed that spark plug a dozen or more times between Vegas and Houston. I could do it in my sleep with the motor hotter than blazes.
Cheers,

Charlie-----


The biggest mistake made when installing these seals is the failure to install the seal on the valve stem in the proper order. The seal must be installed AFTER the retainer (cap) is installed. So, the seal has to be installed when the spring is compressed. Then, the valve keys (locks) are installed and the spring is de-compressed. If the seal is installed on the valve BEFORE the retainer is installed, the retainer will push it out of the groove and render it useless.

Also, these seals are NOT O-rings; they have square edges, not round. They must be installed so the edges are square and not "twisted".