What is the correct amount of torque for a spark plug on a GM (Chevy) 3800 engine. The shop 200 Impala/Monte Carlo shop manual contains a discrepancy.

On page # 6-408. under Exhaust Manifold Installation (left) the manual says to tighten the spark plugs to 27 N-m or 20 lb ft. The same can be said for the torque specification for the right side (page 6-412.)

On page #6-547-548, under Spark Plug Replacement, the manual indicates to tighten the spark plugs to 15 N-m or 11 lb ft (page 6-548.)

Am I missing something here?

What is the proper tightness or torque for a spark plug on a GM 3800 (Chevy) engine - 11 ft lbs or 20 ft lbs?

Thanks in advance for your reply(s),

Bill

 

wrist tight works for me

 

tighten it till it breaks then bac`k off half a turn jfwy tighten it by hand until it stops then like a quarter turn

 

Hand tight/wrist tight would work except that I am indexing the plugs....I noticed about 2% HP gain...Bosch says 15 ft lbs. I guess we'll see.

Thanks for your replies.....

Bill

 

there is 2 diff types of plugs..there is the ones with the lil crush washer on the end and then theres the ones with out..the crush washer ones are like a 1/4 of a turn after there hand tight and the others are an 1/8th of a turn.

you aint going to get 2% hp gain from just changing the plugs or turning one a 1/8th or 1/4 of an inche more.

hope this helps

 

WOW...spark plug indexing doesn't affect horsepower....and here I've been wrong all these years....thanks for the heads up!

 

indexing just changes the length of the gap between the strap in the fucking which a ma call it..putting more gap in means that it takes alittle longer for the spark to make a spark..its like playing with timing almost..

 

I think hes referring to having the straps all face the same direction not adjusting the gap. I dont see any benefit on this on a stock n/a 3.8 cept. I know you can buy indexed sets of plugs. And the old style trick was to buy a case of plugs and find the ones that were close and return the rest since every plus will almost the threads in a differnt way