sparkplug - UL77V -vs- QL77JC4 '78 140hp

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warrior1

Seaman
Joined
May 12, 2007
Messages
56
which plug is better? does it make that big of a difference performance-wise?

my manual calls for UL77V for this engine (78 140hp) but everyone on the forum says QL77JC4.

i am trying to diagnose a hard start issue, and this is one of the last things i need to get (sparkplugs). i currently run new UL77V on this motor.

my engine starts & runs fine on muffs, but put it in the water and it takes a good 5 minutes of cranking to get it to kick off. could the plugs be the issue.

im assuming with the number of people running these plugs, i dont need to worry about interference with the piston top.
is this my missing link in the hard start equation?
 
L

luckyinkentucky

Chief Petty Officer
Joined
Jul 29, 2007
Messages
462
Re: sparkplug - UL77V -vs- QL77JC4 '78 140hp

The ul77V has a higher heat range than the standard ql77jc4. I would only use the 77v if I was going to run 90% of the time at WOT. If you are just pleasure boating I would stick to the standard ql77jc4. Also, I have heard that the ul77v are infamous for carbon fouling if you are running anything short of a speed boat. :)

I would look into how your engine is handling the back pressure of being in the water as opposed to muffs.
 
W

warrior1

Seaman
Joined
May 12, 2007
Messages
56
Re: sparkplug - UL77V -vs- QL77JC4 '78 140hp

well, it is kind of a speed boat, its a carlson cvx, but i dont run it at WOT very much. its kinda hard for the kids to hold onto the ski rope going 60 mph:D
as for the backpressure issue, that has kinda got me stumped.
i will get some of the QL plugs tomorrow.

on a side note, wont fouled plugs consitute a starting problem?

thanks for any and all input.
 
reload

reload

Petty Officer 1st Class
Joined
Jun 29, 2004
Messages
368
Re: sparkplug - UL77V -vs- QL77JC4 '78 140hp

I keep hearing this stuff about starting on muffs and not in the water. I can't grasp the water pressure causing this. I have never experienced it. Its not that I don't understand the concept, I just can't see it happening.
 
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