ul77v vs ql77jc4

does the ql77jc4 take less power at idle to burn than the ul77v
i am running ul77v surface gaps but i dont run wide open for long periods
the mech i use said that haveing and older parts it would idle better at idle and required less fire to run ql77jc4s gapped at 30 to 35 than the surface gaps . evinrude 150 1981 crossflow
thanks benny1963

Re: ul77v vs ql77jc4

Yes, surface gaps require higher voltage. That is one reason they don't work in so many motors...not enough available spark. Not only that, the "U" in the number means it has a built-in resistor, requiring even more available voltage. Personally, I have very little respect for them.

BTW, the "Q" in the other plug means it has a built-in INDUCTIVE resistor. Does the same thing, prevents radio interference, but without the DC resistance of the "U" plug.

Edit: I think I got that wrong. I think the "U" stands for a series gap within the porcelin. Either way, it adds to the resistance.

Re: ul77v vs ql77jc4

tahnks fr im going to try a set gaped at 35
and see if they work a little better.
im loading up a little at idle but have been having trouble with primer sel.
may be leaking a little past into the motor it seems to want to load up a little after it sits ,thanks very much benny b.

Re: ul77v vs ql77jc4

Gap = gap

Ignition voltage sees NO difference in the same gap, be it a surface gap factory fixed at 1 mm or a standard electrode plug gapped at 1 mm, given both plugs are the same resistance.

Surface gapped plug fair better on high compression, higher HP, higher RPM use

Fisherman, trollers, spending much of their time well below WOT often make the switch to standard electrode plugs with greater success, HOWEVER, not all engines have the piston clearance to change plug styles, ALWAYS check to be sure youu have a minimum of .050 between the ground electrode on the plug and the piston dome.

I highly recommend the NGK B8HS and if there is enough clearance BP8HS
these are avail w resistance BR8HS and BPR8HS

if comp is 120 or less try the B7HS
100 or less use B6HS
lower # is hotter