V4 84 140 spark plug quiestion

[delawarerick]

I am in the process of starting and running an old xflow with the first compression reading I got 125 100 125 125 I reread 100 and it had gone up to 107 which I suspect a carbon issue which Chris Carson and I discussed and I am addressing. Now the plug that is called for is ul77v or l16v gapless this is a 16 heat range and is good for performance but tends if not run hard to develope carbon. Since I have a great deal of idling to protect the manatee I was thinking a ql77jc4 gaped at .30 would make an easier starting less carbon building any thoughts. thanks Rick

[racervboat]

I am in the process of starting and running an old xflow with the first compression reading I got 125 100 125 125 I reread 100 and it had gone up to 107 which I suspect a carbon issue which Chris Carson and I discussed and I am addressing. Now the plug that is called for is ul77v or l16v gapless this is a 16 heat range and is good for performance but tends if not run hard to develope carbon. Since I have a great deal of idling to protect the manatee I was thinking a ql77jc4 gaped at .30 would make an easier starting less carbon building any thoughts. thanks Rick ul77v is for sustained high speeds,l77jc4 or ql77jc4 either one the q stands for resistor plug.

[flabum1017]

The QL77JC4 plug is the standard for those, best all around plug. Use an old set of plugs, take it out with a can of engine tuner, run it hard, get it warmed up good and stall it using the engine tuner saving enough to pull the plugs and dump the rest into the cylinders through the plug holes (don't lose the straw in the engine this time), let it soak for 15 - 20 minutes the run it hard as hell for five minutes.... that should get most of the carbon out. A lot of guys won't do this out in the water, but it's the best way to shake all the carbon out.

[staylor]

My 1984 140 always tended to foul the 77 heat range plugs faster than I liked- and the surface gap plug was worse than the gapped plug. Others had this issue too, especially if the motor was run at low rpms for a reasonable amount of total operating time. A common fix for this was to swap to the slightly hotter QL-82C plug gapped to .03 which I ran in my 140 for close to 10 years with no issues- and a lot less fouling.
Doug