At the engine shop today helping tear down a new engine. Owner only had a it a short time but "it didn't run right". The first shop pulled the intake and looked at it but couldn't find the problem so the owner brought the engine to my buddy's shop. First thing we noticed was that a few of the pushrods were bent and that the cam had some unusual wear patterns on it. The engine is fresh inside, close to zero miles since it was rebuilt. Pulled the cylinder heads and noticed that some of the spark plugs were too long. They were 3/4 inch reach plugs in cast iron heads. Looked at it a little closer and the intake valves were crashing into the spark plugs. The corner of the spark plugs had been shaved off by the intake valves. So someone put the wrong plugs in the engine and now it needs a full rebuild.

Well that makes for a bad day...

It's the little things that bite

I cant understand how someone even try putting the long plugs in there. I would think the pistons would hit the plugs but they are probably down the hole pretty far. Well at least shouldn't be that expensive to repair .

Gus

“Some” of the spark plugs were too long.

I guess you just use what you have laying around.

Probably a SB Mopar guy rebuilt it

Yeah only a few of the plugs were the 3/4 reach. I have no idea who installed the plugs or what they were thinking. Don't know if they got confused or didn't pay attention or didn't know what they were doing or what. I've never seen this before. I find it hard to believe that someone would spend a bunch of money getting an engine rebuilt and then install a grab bag of random plugs. Guess we'll hear the rest of the story after the owner gets the bad news. Not sure if he'll say "whoops" or if he'll blame someone else.

How does one not notice two different reach plugs?

If 4 were too long and the other 4 were right I would guess they could have had 2 boxes and didn't check that they were the same.

At one time I bought a dirt-cheap Cordoba 400 for the engine and wanted to perform a compression check before pulling it. Those small-block plugs were coated with carbon and a real pain to get out! No piston contact though and the engine seemed to run fine.

When I first got my 68 Charger, 318, it ran kind of funny.

I found it had short reach, accel plugs in it like a person would use in a big block with iron heads.

Of course no harm done, but seems like a weird error to make.

Maybe somebody thought it would go faster with 440 spark plugs