rotating the slant head

O

oldsurfer

New Member
i removed my head to fix a problem and notice the spark plug sits not center..but off center...does it make any difference if it sits closer to the intake side or the exaust side...i had read it doesn't ..so for looks i have the spark pug over the carb...
 
supposedly the spark plug is supposed to aim at the intake side so the mixture combusts faster, but i don't think it really matters.

it shouldn't be offset, though. that sounds like a defect, but it shouldn't really hurt it, i guess.
 
bairdco said:
supposedly the spark plug is supposed to aim at the intake side so the mixture combusts faster, but i don't think it really matters.

it shouldn't be offset, though. that sounds like a defect, but it shouldn't really hurt it, i guess.
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I've tried them both ways....and honestly can not tell a difference....it might sound different ( I wouldn't know ).......but honestly....no difference in performance.....maybe different kits make a difference ?....SIIK!....


Salty.shft.
 
The only thing a slant head does is clear the frame better. Sure the heads inside combustion area offers better enhanced compression even it is not the right shape. You basically have is just that. A bit o better compression. I got a billet aluminum head from Manic Mechanic. It is the slant head variety.

While I have not used it yet . So I have no input about its performance. I would rather of had a plug going in in the center. His billet head the combustion chamber does looks way better than anything china has offered though. The overall shape inside is what it should be for what it is and is very good looking in person. With that said it is better than a china slant head. The slanted spark plug has no performance enhancing value that I can see.
 
Goat Herder said:
The only thing a slant head does is clear the frame better. Sure the heads inside combustion area offers better enhanced compression even it is not the right shape. You basically have is just that. A bit o better compression. I got a billet aluminum head from Manic Mechanic. It is the slant head variety.

While I have not used it yet . So I have no input about its performance. I would rather of had a plug going in in the center. His billet head the combustion chamber does looks way better than anything china has offered though. The overall shape inside is what it should be for what it is and is very good looking in person. With that said it is better than a china slant head. The slanted spark plug has no performance enhancing value that I can see.
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The only advantages I can see about Jim's heads are they look a whole lot better and run cooler.....but Jim took a lot of time to design ....test...and manufacture these heads.....and I also concur that he provides us with a WAY better product....I'll be purchasing one in the near future as I'm already using all his other products.....but all in all......one or two MPH more.....hmmmm.....that's a lot of money to get to the store two minutes faster.....but still..... I LOVE "EM !


Salty.shft.
 
Besides improved performance, Jim's heads look much better in all aspects simply put. Keep em coming!


I'm pretty sure you could run the China slant heads to the left or right as well...would sure look strange however!
 
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scotto- said:
Besides improved performance, Jim's heads look much better in all aspects simply put. Keep em coming!


I'm pretty sure you could run the China slant heads to the left or right as well...would sure look strange however!
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And you might hit the plug and wire with your knee !

Salty.shft.
 
thanks for the feed back...still no one has said it really preforms great...got better top end..bottom end...but the big thing is all of jims stuff is a work of art at a great price!!!!!!!!!!!!i love this hobbie...don;t need a car lift to work on these ,,motors and all stuff is cheep!!i have $1000 dollars in my 50s style rat rod bike..everwhere i go everyone loves it...will post pictures soon....
 
oldsurfer said:
i removed my head to fix a problem and notice the spark plug sits not center..but off center...does it make any difference if it sits closer to the intake side or the exaust side...i had read it doesn't ..so for looks i have the spark pug over the carb...
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I believe you answered your original question correctly in what you'd read...it doesn't.
 
The slant head has been marketed as a "performance" part... but details are somewhat hard to come by. The angled plug would most likely be to facilitate spark plug indexing so, with that in mind it would prolly be "better" to have the plug on the intake side (exposing max amount of unobstructed spark/flame front to fuel/air) ... but there's some controversy about the effectiveness of indexing *shrug* I do know that in the quest for maximum performance it's more about attentiveness to the smallest of details and all the details than just getting "performance" parts and bolting them on. There may not be a noticeable gain from any one tweak - but add them all together and that's the winner, the devil is in the details lol ;)

What interests me as I've not had a slant head and can't seem to find a pic of the combustion side - is there actually some semblance of a squish band*? This I would think FAR more important than indexing and sadly the stock heads have not even the faintest thought of one, it's just a simple dome... pics would be ossum ifn ya can :D

*squish band: a narrow section of a combustion chamber in which the fuel charge is more compressed by the piston than in the rest of the chamber; designed to help direct the flow of the fresh charge and to improve scavenging
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fuel2b.gif




edit: BTW for those whom may not know & controversy aside - to properly index a spark plug you'd need to remove the head & shim the plug so the side electrode (ground) is away from the center of the combustion chamber exposing the maximum amount of the center electrode & spark to the intake side.
 
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Just tighten a plug into the head mark where its currently at with the Head still attached. In other words mark the plug with a permanent marker where the electrode is pointing. Once the plug is in and tightened by the mark on the plug you'l know where the electrode is pointing. Someone will prolly go through 4 or 5 plugs getting one that happens to line up though.

The slant head design inter ups the squish band. I think a perfect band around the chamber will perform better. The going talk of things does sound like the plug is better to point to the intake side.

Here's a pict on this thread from a long while back buried in the forum.
http://motorbicycling.com/f13/new-slant-heads-80ccs-compression-boost-6621-3.html
 
Here is merely 1 (ONE) place to purchase indexing washers to get your spark plug into the optimum alignment in your cylinder head.
 
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