spark plug

F

fstjohn

Member
can some one show or tell me where the plug gap should be in reference to the valves on a limited so it misses valve. Thanks
 
Anywhere but over the IN valve. Index it so the gap is pointing either toward the EX valve or toward the middle head bolt (#9) on the right side of the head.

Personally, I cut off the ground strap with a .040" cut-off wheel on a dremel right at the bend, then tap the ground strap down flat so that it is a side ground. Another method I used to do back in the limited days was to take a surface gap plug (which I generally dislike) and put a bead of weld on the bottom of the plug so that it is a side ground.

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Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cuts
www.CarlsonMotorsports.com
Celebrating 25 years of service to the karting industry
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Have to give it to you Brian regarding the side grounding ......very good idea.....
assume the plug will be hard to foul-up right ?
 
That is exactly right. I've always been a firm believer in a thunderbolt over sky-lightning as far as being better at igniting alcohol (especially when it's cold - remember methanol has a flashpoint around 51*.) A good ground for a path of least resistance makes a much stronger "bolt" or arc. More direct arc and bigger flame kernal means a more complete burn in the chamber. Yea yea I know, someone will say it only takes so much spark to start the fire (which is true), but what happens if you don't get that teenie spark the first cycle or two and now you have 3 teaspoons of alcohol puddled in the combustion chamber (or more considering the OP is asking about a limited which undoubtedly is running an overly rich at idle Tilly.) I want that sucker to ignite every time! ;)
 
There is a plug already made like Brian is describing.We used them for years in our flathead limiteds.I also when building a limited use to screw the plug into the head with the tach lead and shims before installing onto the cylinder.Then I'd scribe on the head that number to remind me.Usually around .070 -.080 of shims would flush up the plug with the bottom of the threads in the cylinder head.I think Nipendenso made the inverted tip plug we got them from CKI.
 
Is the spark plug on a flathead long or short reach ?, if its long reach then maybe a short reach could do the job/?? don't know just asking...i'am no pro ...
 
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