bought rebuilt 440 engine had autolite 24 tapered plug seats in it. ran it for a couple hundred miles decided to change spark plugs & found out they were suppose to have champion j14y with washers. bought the right plugs and went to install them but they would not fit because of a casting bump above all spark plug holes. the old plugs were 5/8 socket the right plugs are 13/16. Is there a spark plug with washer & 5/8 socket that will work on 440

 

Probably not the original engine for the car. Earlier 440's used the larger plugs.

 

Didn't all 440 use the large plug with metal gasket?

 

What is this casting bump over the spark plug your talking about????.... I don't quit understand...
You can get the gasketed smaller socketed spark plug. But you should not have too !
Something dose not sound rite here....
Shoot us a photo of the hole in the head and the cylinder head. Also if you have it the casting number might help.

 

casting # 4006452 1976-78 not sure how to post photo

 

sent photo to your gmail the hump is right below spark plug hole

 

Mite try the J12YC and see if the body is a little longer? I dont think it is, but it mite worth a look. Also if you have a thinner spark plug socket? Give that a try. I dont see why you should be having an issue... Strange !!!

 

Looks like you are going to have to use the Champion RV12YC ( Or equivalent ) in this case. These are a tapered seated sealed Spark plug. As far as I can tell you are correct when you say that you are unable to install the spark plug because of interference and the gasket style will not seating. (Like the Champion J12YC) My understanding is that these heads are Industrial Cylinder Heads with extra cooling pockets around the valve stems and seats area's.

If anyone has any other info on these Heads please feel free to jump rite in and add to the issue.

 

These heads were used in motor homes too. I had a set of heads like that from a 78 motor home.

 

Try some E3 Diamond Fire plugs from Jegs or Summit Racing.

 

Any Up-Date ?
Have you got it back up and running?

 

So NO REAL ANSWER to my search...I have a 440-03 RV Engine for the year 1973.. I want to change the spark plugs. The Driver side is a PTA. I dont want to install the WRONG plugs & have to redo them. I cant even SEE the driver side first two plugs. I HATE Champion AND WILL NOT USE THEM. Autolite is my plug of choice for American Iron. NGK for my Toyota stuff. What Autolite would I use in this 440-3 from 1973? I just got this and since it is running but missing due to an arcing ignition wire and? I want to go through and start fresh with a new set of wires and spark plugs. I havent pulled a plug to see if peanut or 13/16 or what is in there. I also dont trust that who ever did this did what it should have...It is FRUSTRATING to not have GOOD RELIABLE STRAIGHT FORWARD ANSWERS to a DIRECT QUESTION. . at least it is for me....Any good help here would be appreciated.

 

You should start your own thread so your question will get noticed.
But the answer to the question is you will need to pull the plugs and head to the parts store, both plugs were used in the heads. I don't know why but they both show up so there is no definitive answer without having a plug in your hand from each head.