Valves Hitting Spark Plugs

The Blue Box

Well-known member
So recently purchased a built 200 from ebay. The previous owner had installed oversize valves in it along with a 2v conversion, milled head, decked block and a cam. Upon running the engine (ran pretty bad) i decided to pull the plugs out to read them. The first one i pulled was crimped shut by the valve. It was definetely the valve and not the piston. (i observed it with a probe camera) and the valves looked ok (no cracks or anything.) And only some plugs did this due to where the electrode was positioned when the plug was tightened. ( about half were messed up to an extent.) Does anyone make a shorter plug or recessed electrode plug for the ford sixes?
 
Show a photo of the spark plug.
Also what brand plugs & numbers on it.
 
Yes the ones that were damaged. Thanks
 
Howdy Blue Box:

How big are the intake valves? Very interesting. This is a new one.

IIWIYS, I'd buy some new spark plugs and make on the porcelain where the electrode is attached to the shell, then install the plugs so that none of the plugs have the electrode on the intake valve side. You may have to switch some plugs around or even buy some extra plugs.

Good luck and keep us posted on what you find.

Adios, David
 
What year head is on the engine and what are the valve sizes? This is bizarre.
 
Econoline":1yshs4cg said:
What year head is on the engine and what are the valve sizes? This is bizarre.
Casting says 66. Im not sure the size of the valves. Ill try talking with the previous owner. I solved the problem today by just aligning the spark plugs so that the electrode wouldnt touch the valve. But i had to turn the motor over to get some of them in... If that makes sense
 
CZLN6":ud8ab5xp said:
Howdy Blue Box:

How big are the intake valves? Very interesting. This is a new one.

IIWIYS, I'd buy some new spark plugs and make on the porcelain where the electrode is attached to the shell, then install the plugs so that none of the plugs have the electrode on the intake valve side. You may have to switch some plugs around or even buy some extra plugs.

Good luck and keep us posted on what you find.

Adios, David
Oh cool :D your book is in my lap as im typing this. I did exactly that and it seems to work
 
CZLN6":yym3fm2g said:
Howdy Blue Box:

How big are the intake valves? Very interesting. This is a new one.

IIWIYS, I'd buy some new spark plugs and make on the porcelain where the electrode is attached to the shell, then install the plugs so that none of the plugs have the electrode on the intake valve side. You may have to switch some plugs around or even buy some extra plugs.

Good luck and keep us posted on what you find.

Adios, David

I believe companies make copper indexing washers to allow plug electrodes to be oriented in certain spots.
 
I have the 1.88 valves and although they don't actually hit the plugs, the plugs are indexed to fire into combustion swirl. I swap plugs until a consensus pointing right, old technique squeezing the edges of performance...

I did a compression check on it with my old gauge with stepped plug threads and the da#@ gauge fitting did hit the valve when I cranked it!...

HEADINDEXEDPLUGS1.jpg






have fun
 
just 4 fun, mark the plug as to where the 'arm' is. Screw it in so that the armature (right name?) does not interfere w/the valve...some have 'extended" ceramic/center point, arm.
UR comment on "generic" can create probs. Order exact numbers...
 
Go with a spark plug with less reach. The Autolites are more extended than most other plugs.
Go with Denso iridium plugs which have a shorter reach.
Where is the valve hitting the plug???? Side electrode or where??
 
If you look at the plugs it's got to be the side where the electrode meets the body.
 
I'd like to see HOW the valves are hitting the plugs. I don't believe that is physically possible, the valves run parallel to the cylinder bore and for them to hit the plugs, the valve seats would be intruding on the plug holes. At that point you'd be into the plug threads and physically impossible to only be hitting the electrode.
 
At first I thought the same thing frozenrabbit. But after looking at my spare head and sticking an old plug in there oriented right I can see how, with a big enough intake valve, It could clip the plug strap. The plug projects out into the chamber at what looks to be at least a 60 degree angle to the valves. And the edge of the intake valve is pretty close to the plug, even on my D5 head with 1.68" valves. As the plug projects out it gets closer to the path of the valve.
 
"...just 4 fun, mark the plug as to where the 'arm' is. Screw it in so that the armature (right name?) does not interfere w/the valve...some have 'extended" ceramic/center point, arm.
UR comment on "generic" can create probs. Order exact numbers…"
poor communication skills
 
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