deformation of the new spark plug electrodes on my caddy coupe devill 64

Hello everyone,
yesterday I changed spark plugs with new (preventatively) ordered from (brand see photo) further I changed all belts and coil, cables from spark plugs I described not to confuse it.
After the engine started, the engine sounded as if it were driving on fewer cylinders.
I immediately switched off the engine and, after removing the spark plugs, I was horrified as they deformed.
Thread on new spark plugs is as long as old ?!
this deformation only occurred on the cylinders on the left side of the cylinder 2,4,6,8
on the other hand everything ok, I put back the old spark plugs and the engine goes ok,
after removal, no candle is distorted and the engine is running ok?
What's the moth happening?

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try resetting them again at 32 thou gap and try them again.

2 look like they've never fired, so maybe they were like that when fitted.... don't yell at me, just a suggestion. :-)

This is the thing I do not know if spark plugs OK after unpacking,
but I bought them 10x, 2new , what left me are ok, and 4 on the right side (cylinders 1,3,5,7) are ok too!
But now I can not try it because I have removed the valve covers and I'm waiting for the gaskets !
But then I'll try to get the gasket.

And (resetting them again at 32) does it mean what units I am from Europe?
Thanks Honza

Were the plugs properly gapped when you installed them and then the gap closed you are saying ?


The plugs were properly gapped on 100% everything I had described.

I don't know what happened......


Double check --to see if these plugs are correct for the your car-- pls
The stock pistons on these cars - have valleys cut out in the top of the pistons so i do not see how a piston could possibly be hitting the the spark pug electrode for any reason
The fact that only one side of the engine is a problem is very ODD situation as well

I would really like to know what could have caused your problem

Jason and I use the Autolight spark plug replacement - for the stock Delco plug myself
A more durable longer lasting plug from my own drag race car performance testing on the track


Tomorrow I have to come up with a new valve seal,
then I try to straighten the electrode and put it back there again.
It is true that I did not look at the state of the ignition candle electrodes when ripping, but it is true that the pack was 4 pieces so it is possible that they were deformed already new.
I want to ask you have any hints and tricks for new valve seals ???
to prevent leakage? did I hear that the seal should be stuck in the valve cover?

You always have to inspect and Gap -new plugs out of the box
The stock gap is .035 ( thirty five thousants )

I simply cannot see how you had this problem unless you have no idea what you are doing with the spark plugs
Installing Plugs is about as basic as it gets


The car will run very poorly on plugs that are not gaped correctly
There is a developed feel and technique to using a feeler guage correctly



This is quite a dilemma. As others have suggested, it is possible the plugs were not gapped properly or not the correct part when installed. The fact that this happened to all four plugs on one bank of cylinders and none on the other bank seems like more than a coincidence. 

I'll throw out one other possibility: Is there a chance the left side cylinder head, or both have been off the engine and resurfaced? I don't know how much clearance there is between the spark plug electrode and the top of the piston at TDC but if it is very small and too much material was machined off the head when resurfacing, that could be causing the interference and bending the electrodes.

This seems like a long shot and would have caused this issue as soon as that head was installed.

I did have a head improperly resurfaced by a machine shop years ago and it made it difficult to install and (mechanically) adjust the valves properly.

BTW, .032" converts to .813 mm

The engine is 100% in its original condition with 41,000 miles per owner, all the original head is definitely never out or sharpened and thanks for the transfer to millimeters

In my opinion I'm debilitated !!
I had to check the gap immediately after removing the spark plugs from the box that might have been bad and I'm bothering you here, the candle electrodes straighten the right gap and try and see it!
Thank you very much for your advice I am not a car mechanic rather self-taught :(

From what you said, It didn't sound like the engine had been disassembled. I was throwing this out there just in case.

If you are not mechanically inclinded and experienced in working on car engines --many things you can do will make the car run ---much more poorly --than it it did before you start fixing ( experimenting ) with your Antique Cadillac
Much of the info --is on the internet ( google ) by asking the correct questions
Everyone on this website needs - a basic understanding of the mechanics of working on cars - to understand the answers to the questions that are being asked or you need a good mechanic ( shop ) to keep your car running correctly based on the basic maintenance these cars require every 6,000 miles ( unlike the much newer cars )
That requires DEEP pockets
Studing the service manual for your year car and --understanding it -- could be a very good place to get to know what your car requires to perform perfectly and being sure the proper maintenance is done at the correct intervals
Just doing --this or that --because you think you are improving the engines performance -- ( ex: turning the screws on the carb -- without an RPM meter or oxegen sensor- followed by a very complete tune up ) can and will cause your car to run real bad -- now requiring a shop to fix the problem you caused
It can get expensive with that approach And the cars poor performance is bound to be upsetting to you
There is -a large learing curve -- regarding working on cars which is one of my lifes passions
I do this stuff myself for 50 years -- and own my 64 since new --as much as is possible -to be sure my ride runs as Perfect as is possible to suit my own personal needs and reduce the expense involved in owning a fine Clacsic Antique Cadillac
I do understand that one does have to start somewhere to being to learn and do what is required to help keep the expense of owning these cars within a resonable range

I guess attemping to repair something has its merits and can always be corrected by a shop if all else fails
Finding a good--HONEST mechanic at 50- 75 dollars an hour will be the next major problem
They are all good for a short while until they start with the mechanics BS that usually makes little sence to a person who really understands the issue at hand
The guys on here have been wrenching these cars for decades with hands on experience to be able to advise others on the subject
Just my 2 cents on FIXING our own car




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