Spark plug with 5/8 hex ?

[417guy]

I usually change the plugs in my 383 roadrunner every winter. Maybe overkill, but I hate to have issues on a long cruise to a show. It has old hooker 1 7/8 tube headers on it, and some plugs are challenging to change. I’ve been trying to research an equivalent plug,but with a 5/8 hex. Spent too much time already looking. Just wondering if anyone else had the same idea, looks like it would help with some clearance to the header tubes. I’ve got all the wrenches, sockets, hose, etc and can get it done, but wouldn’t mind if it was a little less job. Thanks !

 

[mopar jack]

Mopar action Feb 2024 issue in the tech section R.E. mentions using plugs from 1995-99 Neons.

 

[kramer]

Those neon spark plugs have a 3/4 reach where the factory big blocks use a 3/8 reach spark plug, alot of the aftermarket aluminum big block heads use the 3/4 reach spark plugs. I believe Accel used to make "header" spark plugs with the smaller 5/8 hex.

 

[440 4 speed]

Those neon spark plugs have a 3/4 reach where the factory big blocks use a 3/8 reach spark plug, alot of the aftermarket aluminum big block heads use the 3/4 reach spark plugs. I believe Accel used to make "header" spark plugs with the smaller 5/8 hex.

I would dump the headers if it were mine, but not suggesting you do.

 

[dadsbee]

I would dump the headers if it were mine, but not suggesting you do.

HA! My suggestion would be to stop wasting time and money changing the plugs every year...

 

[RJRENTON]

I usually change the plugs in my 383 roadrunner every winter. Maybe overkill, but I hate to have issues on a long cruise to a show. It has old hooker 1 7/8 tube headers on it, and some plugs are challenging to change. I’ve been trying to research an equivalent plug,but with a 5/8 hex. Spent too much time already looking. Just wondering if anyone else had the same idea, looks like it would help with some clearance to the header tubes. I’ve got all the wrenches, sockets, hose, etc and can get it done, but wouldn’t mind if it was a little less job. Thanks !

WHAT plugs are you using now? The origional 383 engine plugs were 3/8" reach, 13/16" hex Champion J-11Y or equilivant. I you're looking for more header clearance and a smaller but equilivant plug, consider Champion CJ-6Y, extended nose. Its 3/8" reach, 3/4" hex, similar heat range . If you have changed to aluminum heads, which generally require 3/4" reach plugs, similar to Champion N-10Y or N-11Y or equivalent. Champion RC-12YC are 5/8" hex, 3/4" reach medium heat range plugs. It would help to know what you have now.....just my opinion of course.....
BOB RENTON

 

[417guy]

Those neon spark plugs have a 3/4 reach where the factory big blocks use a 3/8 reach spark plug, alot of the aftermarket aluminum big block heads use the 3/4 reach spark plugs. I believe Accel used to make "header" spark plugs with the smaller 5/8 hex.

I remember those, but can’t find any numbers that are 5/8 hex. Thanks for the comment !

 

[417guy]

WHAT plugs are you using now? The origional 383 engine plugs were 3/8" reach, 13/16" hex Champion J-11Y or equilivant. I you're looking for more header clearance and a smaller but equilivant plug, consider Champion CJ-6Y, extended nose. Its 3/8" reach, 3/4" hex, similar heat range . If you have changed to aluminum heads, which generally require 3/4" reach plugs, similar to Champion N-10Y or N-11Y or equivalent. Champion RC-12YC are 5/8" hex, 3/4" reach medium heat range plugs. It would help to know what you have now.....just my opinion of course.....
BOB RENTON

I’m using RJ12YC plugs. Looks like a 3/8 reach, 13/16 hex. Have also used Bosch WR9FP,same reach and hex, which are NLA. Thanks for your comment.

 

[pnora]

I usually change the plugs in my 383 roadrunner every winter. Maybe overkill, but I hate to have issues on a long cruise to a show. It has old hooker 1 7/8 tube headers on it, and some plugs are challenging to change. I’ve been trying to research an equivalent plug,but with a 5/8 hex. Spent too much time already looking. Just wondering if anyone else had the same idea, looks like it would help with some clearance to the header tubes. I’ve got all the wrenches, sockets, hose, etc and can get it done, but wouldn’t mind if it was a little less job. Thanks !

On a healthy motor you should easily get 10k on a set of plugs. If it runs leave it alone.

 

[417guy]

On a healthy motor you should easily get 10k on a set of plugs. If it runs leave it alone.

It gets driven about 5-6k a year, so I suppose I’m just a little too cautious. Thanks for your comment.

 

[Gus chiggins]

I would dump the headers if it were mine, but not suggesting you do.

I suggested that on another thread, jeez, i did not know headers vs manifolds was such a tripwire issue, I like the HP manifolds btw

 

[Gus chiggins]

I’m using RJ12YC plugs. Looks like a 3/8 reach, 13/16 hex. Have also used Bosch WR9FP,same reach and hex, which are NLA. Thanks for your comment.

That depends on the cylinder heads, yes? I have rv heads with the little bump by the spark plug hole. 452 heads

 

[early2drsedan]

look up ngk plugs there the best .

 

[PurpleBeeper]

I remember those, but can’t find any numbers that are 5/8 hex. Thanks for the comment !

The Accel plugs are shorter, but still use the same hex