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cdupuy
Samba Member
Joined: November 23, 2011
Posts: 157
Location: AZ
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 Posted: Fri Jan 11, 2013 6:25 pm Post subject: Spark Plug angle |
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| anyone changed the spark plug angle to point towards the intake valve more, if so what was the power increase? |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 76911
Location: Sneaking up behind you
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| Posted: Fri Jan 11, 2013 7:18 pm Post subject: |
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You can but "index" shims so you can optimize the location of the electrodes.
| Quote: |
4. Indexing
This is for racers only !!
Indexing refers to a process whereby auxiliary washers of varying thickness are placed under the spark plug's shoulder so that when the spark plug is tightened, the gap will point in the desired direction.
However, without running an engine on a dyno, it is impossible to gauge which type of indexing works best in your engine. While most engines like the spark plug's gap open to the intake valve, there are still other combinations that make more power with the gap pointed toward the exhaust valve.
In any case, engines with indexed spark plugs will typically make only a few more horsepower, typically less than 1% of total engine output. For a 500hp engine, you'd be lucky to get 5hp. While there are exceptions, the bottom line is that without a dyno, gauging success will be difficult |
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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Steve Arndt
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Joined: August 01, 2005
Posts: 1780
Location: Boise, Idaho
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| Posted: Fri Jan 11, 2013 8:19 pm Post subject: |
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Pointing to the intake dates to the hemi domed piston design where the plug was shrouded by the dome.
The burn progresses best by aiming the plug towards the hot side (exhaust). The flame kernel begins on the hot side of the chamber, so point the plug at the exhaust. |
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Steve Arndt
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Joined: August 01, 2005
Posts: 1780
Location: Boise, Idaho
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modok
Samba Member
Joined: October 30, 2009
Posts: 26785
Location: Colorado Springs
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| Posted: Fri Jan 11, 2013 8:27 pm Post subject: |
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| Steve Arndt wrote: |
Pointing to the intake dates to the hemi domed piston design where the plug was shrouded by the dome.
The burn progresses best by aiming the plug towards the hot side (exhaust). The flame kernel begins on the hot side of the chamber, so point the plug at the exhaust. |
Yep, I agree. You can't change the angle too much because you gotta reach the plug through the hole in the tin, but you can move it out and toward the ex about .100" each way, and that is what guys have been doing since the 70's! Gotta grind the fins some to make the socket fit, remember to do that before assembling the engine! (ask me how I know  ) |
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miniman82
Samba Swamp Donkey
Joined: March 22, 2005
Posts: 9515
Location: Southern Maryland
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| Posted: Fri Jan 11, 2013 11:40 pm Post subject: |
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| modok wrote: |
| You can't change the angle too much because you gotta reach the plug through the hole in the tin |
really? 
Something tells me that if you care enough to go playing with the angle of the plugs, you're not going to care about having to mod the tins to make it all work. Another alternative is dual plugs. Leading/lagging, simultaneous, whatever you want.
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I just wanted to bitch but I'm getting no sympathy. |
Welcome to the Samba. |
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gears
Samba Member
Joined: October 28, 2002
Posts: 4391
Location: Tamarack, Bend, Kailua
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| Posted: Sat Jan 12, 2013 6:06 am Post subject: |
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It's tricky finding a good angle for one of the lower plugs (where it's toward exhaust, but can still be removed easily). I believe top fuel guys have actually put another plug downstream of the exhaust valve.
In this photo, only one plug in four is indexed "close" to where it should be. Eventually, I began leaving the plug seating surface as the final machining step, allowing precise indexing of each individual plug.
(Uppers are 12mm, lowers are 10mm)
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aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
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'87 Syncro GL 2.5
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R-Baja
Samba Member
Joined: September 22, 2008
Posts: 164
Location: Out West
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| Posted: Sun Jan 25, 2015 6:50 pm Post subject: |
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| Do you have to remove a couple of push rod tubes to get to the lower plugs? |
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gears
Samba Member
Joined: October 28, 2002
Posts: 4391
Location: Tamarack, Bend, Kailua
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| Posted: Sun Jan 25, 2015 7:43 pm Post subject: |
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No, but the sparkplug socket must be modified slightly.
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aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com |
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mark tucker
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Location: SHALIMAR ,FLORIDA
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| Posted: Mon Jan 26, 2015 2:15 pm Post subject: |
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down stream of the exhaust valve????as in the header??? I think somebody is confuzzing a o2 sensor for sparking bolt  moving the plug around isant an easy task on a vw.but it can be done.but how do you know if it realy did any thing or was worth the work..... |
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gears
Samba Member
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Posts: 4391
Location: Tamarack, Bend, Kailua
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| Posted: Mon Jan 26, 2015 4:30 pm Post subject: |
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Mark .. You'd have to take that question up with the TOP FUEL guys. Obviously, we VW guys wouldn't see one iota of benefit from that.
My comment was in answer to someone who stated that angling toward the exhaust was bogus. It isn't. Angling toward the intake is like placing a small cup facing the natural swirl of the incoming charge .. of virtually no consequence in most applications, but of at least some consequence in an all-out performance application.
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aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com |
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Mon Jan 26, 2015 5:01 pm Post subject: |
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| I know why the plugs are angled,but never seen any in the exhaust execpt for the old flame thrower stuff. |
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Boolean
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