By Jerold Interlicchia (Drifty) on Unrecorded Date: Edit

Have heard so much about the Bosch plugs,did indeed get some.My question is do I gap the Bosch #7557 the same as the champion RC12YC plug in my briggs 16HP?Briggs won't even talk to me about this and hard to get info from Bosch,feel fortunate enough to just find them.Have some nasty hills at camp and even a 5% increase in power would be better than what I have now.Would welcome any info anyone has about this plug.
Thanks,
Jerry

By ISAAC EISENMAN (Tropicjungleboy) on Unrecorded Date: Edit

hey jerold:
the bosch + 4 spark plugs are "factory gapped"...their 4 electrode's legs are "adjustment free"...anyhoo the gap still the same than for regular spark plugs on those engines...(0.024-0.028)......the reason for those spark plugs to be more efficient than regular ones is just because has 4 "spark's jumping alternatives" instead of only one..( sparks are smart!!!they always goes on the shorter/stronger point so chances to fould this bosch + 4 plug are 4 times harder than with regular plugs...and great blue spark makes better bouncing!!!

By MaxRules (Brandon_price) on Unrecorded Date: Edit

Jerold, the Bosch plugs I have are 4418 and they are the +4. There could be two different plugs for the same engine, but I think you may have the regular type and not the +4. Does yours have four electrodes or one?

By Jerold Interlicchia (Drifty) on Unrecorded Date: Edit

Thanks for the info guys,but my ignorance is showing here a bit.Have not gotten the plugs as yet,had to order.Don't know if they are +4 or not.Anyway,Brandon,I called Rec. Industries to get the plug # on my max II and was told it was the RC12YC champion.My Max is at camp and did not have the 5/8 wrench to remove so I called Rec. Industries to find out.Well anyway Pep Boys crossed the #s to a bosch and that is where I got #7557.I wonder if that is a standard Bosch plug or the +4,don't know and will call tomarrow to find out.Brandon, did you notice an improvement in the performance and power after installing the Bosch?How about you Issac?Not into speed at all just power when needed especially up steep hills.Difference in plugs from the 16 - 18HP brigss?Maybe your correct Brandon!!!
Thanks,
Jerry

By ISAAC EISENMAN (Tropicjungleboy) on Unrecorded Date: Edit

hey jerold: it's a huge difference on duty to have bosch +4 spark plugs...and the reason is simple:

you get 4 times more chances to get "clean blue spark" on every single explosion moment ( half time of every two rpm on 4 cycle engines and all time on 2 cycle motors) than a single spark plug leg...that's special true wen you get "extra oil mixture/dirt/" on cylinder chamber...bottom line is that is a good investment to replace regular plugs by bosch +4 ..........happy bouncing!!!