Track Tac

Autolite "X" plugs Letting the cat out of the bag.

Attempting to figure out heat range suitability by using cross over charts is a waste of time. Pick a brand and experiment within that manufacturer. Neither do I think that inserting a plug to its maximum depth in an effort to increase compression is necessarily the right thing to do. Remember that the profile and depth into the combustion chamber will influence flow. I have done some experimenting (with animal heads) with surface gap, conventional, and Autolite X plugs. I find that the x plug when installed at the proper depth, gives the best flow at valve lifts that I deem important.
 
I have motors from KSR, Tod Miller, Jerry Worsham, and Gary Freeze, these are some of the best there is and every motor has come with a AR3910x. I figured they knew what they were doing and did their own testing. feel free to stick whatever plug you like in your motor. I am currently without a dyno or a flow bench so I just keep my 3910x plugs clean and run them.
 
Yes, on an animal head, the flow will be better with the plug shimmed up, but it'll hurt the performance on the dyno from my experience (on stockers.) There's some good argument for wanting a hotter plug for the already over-rich plate engines, and it'll show up on an A/F meter, but I still end up back on the same old 3910X plug at the end of the day. Something you may want to experiment with is a slight change in ignition timing. Having that plug and extra .080" in the combustion chamber may not seem like much, and at the speed of the flame kernel when ignited it may be immeasurable, but it is something to consider. A slight movement of the coil will change the timing considerably. I've made an adjustment opening the coil air gap additionally and found that to help with the 3910X plug.
For sure, there's no one way to build an engine to make solid power. From J-remey's post above -- 4 different builders' engines in one pit. I bet they all run fine, but all are built slightly different. My guess is that one is a favorite of the driver whether it makes the most power on the dyno or not.
 
I've played with plugs especially in plate motors when my son was running purple plate, but after lots of reading, several high profile builders all stated the AR3910X made the most power on the dyno so I stuck with them. I however am still very interested in seeing dyno results on the Brisk plugs with built in capacitor... they are supposedly worth some additional HP on these motors, but they are pricey...
 
J'-remy said:
THANK YOU! for this info!!! Autolite would barley speak to me and told me they would not give me advice based on a non OEM application. The fellow also said these plugs were no longer being made i have no idea but he said he could not find the part number in the system and that was his conclusion.
BUT.... these engines seem to only foul on the grid sitting at idle for too long. Several Top engine builders (who all use the 3910x plug) told me a hotter plug will not fix a carburetor that is out of adjustment.
Thake it for what its worth.. all these guys have dynos. I have also been told enriching the pilot will also aid in fuel delivery at high rpm. clearly why you don't see clones idling on the grid
Click to expand...
I reached out to the Denso Iridium Designer. He made it very easy to get a plug for clone that don’t foul. I’d like to see if any of these plugs show advantages on a Dyno.
 
Have ran the E3 .106 in my son's jr1 clone and predator all las year. Runs great and never had a problem. We are the only ones to run them in our area.
 
You must log in or register to reply here.
Back
Top