1973 115 Hp Evinrude

Larson 1650 Trihull approx 1100 lbs+2 to 3 adults

Since I don't have a history on this motor I am looking at replacing parts as money allows. On iboats they list two brands of ignition coils for my 73' 115 hp. Anyone have oppinons on which is better Sierra or Mallory. Engine has miss at idle, I have rebuilt carbs and replaced fuel lines. I am going to do a decarb on the cylinders.

I have another question--"Why Champion plugs?" seems like everyone is saying Champion.

L77JC4 or QL77JC4 which is better for trolling, which gap .030 or .040 boat will be used mostly for fishing but want to get to the hole first.

I have another brand in it now, plugs come out wet and black.

Sorry if this is repetitive.

Thanks for the previous help!!

Re: 1973 115 Hp Evinrude

motor is designed to use Champions, the Q stands for quiet, if you have fish finder, electronic, keeps the interference down. fast speed is .030 both .035, and lot of idling, trolling .040. wet plugs is a rich condition, which is carbs, it has fixed jets, so the float may be set high.

what is your compression? Mallory / Sierra they both meet the specs.

Re: 1973 115 Hp Evinrude

Warmed up the motor on muffs and removed plugs to spray in Deep Creep, Plugs on 1 and 3 gapped at .020, 2 and 4 gapped at .040. I checked them a month ago thought I gapped at .040 when I decarbed then. Could a piece of carbon have hit them?

I have just rebuilt the carbs the floats were just a touch high.

I am runnig the NKG equivilent of the Q champions.

When I get the decarb done a friend is letting me use his compression guage.

Thanks for the info tashasdaddy!

Re: 1973 115 Hp Evinrude

GET CHAMPIONS IN IT. the piston may have hit the plugs.

Re: 1973 115 Hp Evinrude

I have ordered the Champions, also on the air intake I only have part of the original decal with what looks like a ul77v for a plug. Is that different than the QL77JC4 and what is the performance difference?

Re: 1973 115 Hp Evinrude

Took out #1 NKG-BZ7HS 10 again gapping it to .040 after treating with deep creep plug gap is now .025. With the plug out brought #1 to top center-about 3mm x 3mm piece of carbon was chipped off cylinder head.

Here's the question:
Is the champion plugs reach shorter than the NKG's?

Will changing to the ul77v correct this and will the motor be as efficient?

Re: 1973 115 Hp Evinrude

Just picked up the Champion plugs I special ordered

They are the same reach as the NKG's

Picked up the NKG equivilent to the Champion UL77V - I'll try them out tomorrow.

What's up - Has anyone had this same issue?