Cylinder heads spark plug holes tapered or not?

[eabrillon1978]

Dumb question maybe, but changing out the plugs today.

Do the stock heads have a tapered seat or not? Have always used the washers that come with the spark plugs, but am starting to wonder if I should have not been using them after all these years. After taking a close look at that today, it appears they are tapered.

 

[Allan]

The year may matter,

Gen IV and earlier do not use a tapered seat plug.

Gen V ........................?

 

[Viper808]

If the recommended spark plug for any engine comes with a washer / gasket it should be used. The washer serves several purposes.
It has been designed to have built in "crush" so when you torque the plug down it seats properly . However, its a one time deal. you should not reuse the gasket/washer if you take it out again for ispection as since it has already been crushed it wont torque down the same but more importatnly and waht most peole dont know is that the Gasket/washer performs another critical function of "heat transfer". A re-used washer /gasket will not condct the heat away from the plug as efficiently and therefore the plug will run hotter and loose its effectiveness and durabilty.

 

[Jack B]

Please explain why the thermal conductivity of the washer is going to change when reused.

If the recommended spark plug for any engine comes with a washer / gasket it should be used. The washer serves several purposes.
It has been designed to have built in "crush" so when you torque the plug down it seats properly . However, its a one time deal. you should not reuse the gasket/washer if you take it out again for ispection as since it has already been crushed it wont torque down the same but more importatnly and waht most peole dont know is that the Gasket/washer performs another critical function of "heat transfer". A re-used washer /gasket will not condct the heat away from the plug as efficiently and therefore the plug will run hotter and loose its effectiveness and durabilty.

 

[speedracervr4]

OP, I have a set of heads off my 99 in the basement packaged up if you need/want me to take some pics or see if they're tapered.

 

[steve911]

According to Champion, Bosch and NGK, ALL Vipers use a 14mmx1.25 thread pitch GASKETED spark plug. No tapered seats.

 

[Viper Specialty]

Gen-1/2/3 use a gasket. Gen-4 and Gen-5 use a tapered seat.

 

[Boxer12]

According to Champion, Bosch and NGK, ALL Vipers use a 14mmx1.25 thread pitch GASKETED spark plug. No tapered seats.

This quote and Allen (above) are WRONG!!! Dan is correct. Gen IV (and V) use tapered. If you have a GenI-III, make sure your heads haven't been worked on...The OEM plug for Gen IV is Champion RE10PMC5 Single Platinum Spark Plug. The NGK replacement is NGK 3381 LZTR5AGP Single Platinum Spark Plug, and the Bosch replacement is Bosch 6732 HR8SPP300V Single Platinum Spark Plug.

 

[Steve M]

The year may matter,

Gen IV and earlier do not use a tapered seat plug.

Gen V ........................?

Bad info...just changed the plugs in my '08, and they were definitely tapered seat.