67 Mercury 350 no top end speed

[kanadiankrawler]

67 merc 350 <br />problem no top end speed<br />motor starts fine first turn of the key<br />checked spark - bid fat and blue<br />compresion ok 115's<br />primer bulb hard and butterflys opening <br />idels just fine - runs good just can't seem to get full throt ...<br />could the high speed jet in carb be pluged <br />can i clean it without removal<br />or could i have spun the prop <br />boat is new to me 4 weeks old<br />any help would be great<br />working on a limited buget<br />K.

 

[WillyBWright]

Re: 67 Mercury 350 no top end speed

Welcome to iboats.<br /><br />I'd bet on a restricted main jet. Best way is to take the carb apart and give it a good cleaning. Spun prop hubs let the motor race without producing much thrust.

 

[alcan]

Re: 67 Mercury 350 no top end speed

Describe in detail how you are using your motor controls. Are you trying to run on the warm-up throtle?

 

[Chinewalker]

Re: 67 Mercury 350 no top end speed

Remove motor controls from the equation and see if you can manually advance throttle the full range - with the motor in gear - not neutral!<br />If high speed jet is plugged, the motor would simply stall out as you advanced off the low speed circuit. Spraying mixed fuel (not QuikStart!!) into the carb while running will also tell whether the jet is working or not. Actually, you should be able to see the fuel coming out of the jet at speed.<br />Are you getting spark under compression? Spark in the open air takes less resistance than spark under compression. One of those inline spark testers can check that, or try pulling a plug wire with motor running (with thick gloves or insulated pliers!!) If motor continues to run, unchanged, then it wasn't firing on that cylinder. If it immediately stalls, then it wasn't running on the other one.<br /><br />- Scott