Spark Plugs, Open Animal

W5R

New member
Flattop gave a variety of good choices. I really like the Denso plugs we also stock and sell them, although you may or may not find them at your local Walmart or auto parts store - I have no idea if they stock them. The problem with the fine wire plugs is that they foul even easier. If you find that you're fouling plugs...my thinking is that your problem is not with the spark plug heat range, it's with your carb tune (or you're simply letting it idle on the grid too long.) This has always been a problem with bigger Tilly's drilled with a very rich pattern for low rpm and a reason why I like using the Mikuni accelerator pump carbs instead.
My experience has always shown me that the higher the compression, the colder the plug that needs to be used. It would seem to me that you're wanting a hotter plug thinking that it will better burn a too rich condition that is fouling your current plug. A hotter coil, with more voltage at the plug gap, would make more sense to me.

The 3910X is a fine plug for a stock class application where you are simply trying to displace the volume in the combustion chamber. Don't believe the hype of having several (more than one) ground straps. I do, however, like a bigger flame kernel (which also helps resist fouling.) It'll take a big charge to jump a larger gap.


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Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
28 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
Just to be clear...im not using the 3910X for any reason other than that is what the original builder put in the engine when he built it, so that is what I used. Since then I have added a good bit more compression with a domed piston, and a bigger carb using a 28mm Clements pumper carb instead of a 304 dominator Tilly. Some of the tracks we race at will completely stop the field during every caution, those are the tracks where the plug will foul usually. I have no problem fouling the plug on other tracks that allow us to keep moving under caution and never completely stop the field unless there is a bad wreck, which then we usually shut off the engine when we stop.
 

flattop1

Dawg 89
Zach
Just because that's the plug that was in it really means little, although one would expect the builder to have the correct plug in.
If you do not want to try the denso plugs
Autolite does have the 3910 in a standard style.
In a stock clone the recommendation is do not let the engine idle for long with the ,3910x plug.
Being it's a NASCAR driven design maybe the four prongs are there so at least one is left by the end of the race.
 

W5R

New member
Been using NGK BP6RES I think its called and have really began to like that plug...seems perfect for what I wanted
 
Been using NGK BP6RES I think its called and have really began to like that plug...seems perfect for what I wanted
I have used a BPR6ES (or non resistor BP6ES) for years and years. Best plug I have found. Hard to foul one IMO. 5 is a little hotter, 7 is a little cooler
 

W5R

New member
I have used a BPR6ES (or non resistor BP6ES) for years and years. Best plug I have found. Hard to foul one IMO. 5 is a little hotter, 7 is a little cooler
I was wondering which way the numbers went for a hotter or colder plug for the NGK stuff, thanks for that info. I now have the BP6RES in all of my opens instead of the old 3910X plug i was using and am happy with them, alot harder to foul you are correct
 

will_ivy2

Member
Whats
Bosch Platinum 2. It has 2 electrodes. i get mine at Walmart. There are several numbers. Get them and try them, just make sure you get ones with a gasket seal instead of the taper seals. Do you buy your fuel as a pre-mix? What % of Nitro are you using?


What’s the part number for the Bosch plug?
 

Jimbo

If you talk the talk you should walk the walk
Just curious
W5R and btrammotorsports i see you guys are listed as new members.
It seems to me that i have seen you guys on here many times in the past.
:unsure:
 

flattop1

Dawg 89
Jimbo if you click on the username it shows WR5 as joined in 2013 .
last seen in 2018 .
its a computer/data thing .
This post being brought back from 2017.
 

Bumpy

Member
Was wondering how the autolite numbers went as far as heat range, I see what you mean thanks
Did some research on AutoLite cross references and a couple of the sites actually said that
AutoLite does not have a standard code between each family of plugs. So an increase in a
certain 2digits in one family does not mean the same in the 2digits of another family.
The X-series does not follow the code for other AutoLite plugs.
Weird.
Find a plug line (NGK or whatever) that has a variety of heat ranges and start cold and
move hotter until you find a plug that works.
 
Silverback, I apologize if I spoke out of turn, or in error. Thing is, when a post follows my post, with no reference, I take it to mean you're talking to me. Apparently I was mistaken.
 
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