Spark Plug Indexing Questions (updated with pic)
#315308
05/11/09 07:52 PM
05/11/09 07:52 PM
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Joined: May 2005
Posts: 4,745 Florida
BDW
OP
master
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OP
master
Joined: May 2005
Posts: 4,745
Florida
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The other post on distributor phasing got me thinking about spark plug indexing.
1) On a 340, which way should the gap opening face? Towards manifold? 2) I see both "flat" and "tapered" washers for this? What's the difference?
Thx
Last edited by cnxt; 05/12/09 07:37 PM.
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Re: Spark Plug Indexing Questions
[Re: BDW]
#315309
05/11/09 07:57 PM
05/11/09 07:57 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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(1)I believe so (2) some plugs have tapered seats (for furd iirc), our plugs take flat washers
Last edited by RapidRobert; 05/11/09 08:02 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Spark Plug Indexing Questions
[Re: 70sixpkrt]
#315314
05/11/09 09:10 PM
05/11/09 09:10 PM
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Joined: May 2003
Posts: 15,487 Florida
scratchnfotraction
I Live Here
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I Live Here
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Posts: 15,487
Florida
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I have done it on just on a stock rebuild a few times and got a noticable gain in performance I will add that its not just facing all the plugs the same way,it is faceing the plug the correct way for the cyl only as in the valves move around in the head depending on the cyl e,i,i,e,e,i,i,e looking at the exhast manny this is the valve arangement so to speak,so the plug would face the corrosponding direction I have not done it in a while but,seems I allways faced the open part of the gap towards the cold intake charge not real sure wich way now I thinks on it but it what RR said in shade tree lingo the plug gaps dont all face the front of the engine they would face the correct direction per cyl I will stop now... I just wish I had wrote it down be fore I forgot
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Re: Spark Plug Indexing Questions
[Re: scratchnfotraction]
#315315
05/11/09 09:12 PM
05/11/09 09:12 PM
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Joined: May 2003
Posts: 15,487 Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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oh and drilling the holes in the cap for ions to get out helps stop cross fire in the cap at high rpms just not good for wet weather and I only did that on chivy HEI dist on the BB mud truck
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Re: Spark Plug Indexing Questions
[Re: MNobody]
#315319
05/12/09 07:11 AM
05/12/09 07:11 AM
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Joined: May 2003
Posts: 15,487 Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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IMO,its best to set a head up for indexing while its off the block and you can see the comb chamber then # the plug acordingly to the cyl its free performance and a smoother running engine for some easy labor when puting one together I have faced the plug opening towards the itake valve and have lined them all up in line with the little rectangle indent in the cc at the plug hole but as stated...putting them in so the plug gap faces the expanding "wedge" makes for a complete burn and more leverage pushing down on the piston thats why its called a "wedge head"
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Re: Spark Plug Indexing Questions
[Re: BDW]
#315321
05/12/09 10:08 PM
05/12/09 10:08 PM
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Joined: May 2003
Posts: 15,487 Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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ok I have lined them up in line with the recessed pad area off the plug hole and I have lined them up with the open gap of plug facing the intake valve need to know which way the shape of the of the cc on the heart shaped closed chamber heads swirl the intake charge around to to get it positioned in the right spot on the #302 heads, IMO now I have also thought on putting the gap faceing into the cyl,so the gap faces the large side of the wedge to fire it from the small side and burn towards the big side maximizing the wedge effect of the wedge head which IIRC is the right way for it to be facing maybe someone else will correct me if I am wrong
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Re: Spark Plug Indexing Questions
[Re: scratchnfotraction]
#315324
05/13/09 09:21 AM
05/13/09 09:21 AM
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Joined: Jan 2003
Posts: 14,610 Not2farfromNashville, TN
Rug_Trucker
I Live Here
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I Live Here
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Not2farfromNashville, TN
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I could have sworn on the slant site they said face the opening towards the exhaust valve.
I know I smooth out the pocket where the plug is for flame travel towards the exhaust when I grind the chambers.
From what I have read indexing is worthless on the street, and mild race applications.
Cutting the ground strap might do something.
"The only thing to do for triumph of evil is for good men to do nothing"
"NUNQUAM NON PARATUS!"
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Re: Spark Plug Indexing Questions
[Re: RapidRobert]
#315327
05/13/09 10:00 AM
05/13/09 10:00 AM
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Joined: Nov 2007
Posts: 1,476 Oh
RacerGofKGB
Got The Big One
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Got The Big One
Joined: Nov 2007
Posts: 1,476
Oh
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Quote:
Quote:
Cutting the ground strap might do something.
thats what I did & though I dont know how much it helped as it was on a new build but I felt good about doing it
OT What is this ground strap cutting that you speak of?
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