Split fire plugs

This has probably been whipped before and I just missed it but is there anything to be gained by using split fire plugs or is all that just hype. I'm about ready for the 1K finger wave check up on the Ultra and I thought if the Split fires were any good, I'd consider going that direction.

I've used the "Screamin' Eagle" split-fire type in my Sportsters & while there's no performance gain, they do seem to last a very, very long time.

By no perforamnce gain, I take it you mean in every way: torque, power curve, MPG?

Right. Regular, inexpensive Autolites work as well as any & better than the stock plugs, but they don't last as long. I ran a set of the SE split-fire type for 2 years in my '95 Sportster (around 20,000 miles), checking periodically & they always looked fairly new - gas mileage never changed & neither did anything else.

I've tried several types on the dyno too & have never seen a single HP increase or change in the powerband. The only noticeable difference (other than lasting longer) I've seen is with the expensive Denso Iridium plugs & I like those - but - the only difference is the engine starts so quick you don't even hear the starter. I've used those in my 13:1 compression race engine, but again, no more HP on the dyno.

Thanks ever so much for the info. You just can't beat practical experince. Guess I'll stay with the regular plugs although I do like the point of the Denso's firing the engine quickly.

Yea...I have tried these too. I have a softail heritage with 6500 miles and replaced plugs at 5000....can't seem to tell any difference....checked them about 500 miles ago and they do look new still. Probably not worth the little bit extra they cost but what the hell..its only a few $$$$$

I did use these in an 69 Mustang back a few years ago and dyno tested it and gained about 8 hp...just FYI.....

Looks like I might as wel go with the Autolites in the bike and may do split fires in my 71 Mustang which I rarely if ever drive anymore. Thanks for all the info!!!!!!!!
Merry Christmas to all!!!!!!!!!!

Very cool....I had a 71 red mustang..351 cleveland

Happy Holidays to you and your family also !

I probably have 10 sets of good extras but still swap them for new every spring. $10 well spent for me, it's not like a V8 or something - remove old gap new and install 10 min - done.

spark plugs are a myth. i don't even use them. just epoxy the wires in the holes and you're be fine. you don't really need em. it's all just a big scam:drunk:

Orielly here carries the Autolite 4164 plugs for about 2.25 each.
I change them out 2 times a year wheather they need it or not.
Try to carry a spare set in my saddlebags too.

sure

but realize my 08 egs has over 32,000 miles on it too.

I use the split fire, couldn't tell you that there is a difference, except the time I took it in for service and it came back with hd plugs. Had to go back and get them back sice they where new. I've only chaged the plugs once since 03 maybe twice. they seem to work as well as always. so I would only chage them out when sugested and not worrie about it. since I only have about 15,ooo I guess I'm about right.