nissan 3.5 spark plug gap

[fast525]

Hey guys , <br /> I've been unable to find the year of this one on modelguide , NS3.5A , 309-1, 87137 . The spark gap listed on the cover says 0.04 but it does'nt run at that gap . I can open it up a little (.20) and it runs but it gets a little hot . Anyone know the gap ? I know plug gap affects timing and I put a new impeller in (pre-season tune up) as I do on all my motors at the first of the year , but this one is new to me and I only picked it up for a friend to put on his sailboat . Any help would be great . Jeff

 

[rickdb1boat]

Re: nissan 3.5 spark plug gap

The gap is listed as: 1.00MM Gap<br /><br />Check this link out for more info:<br /><br /> Nissan

 

[fast525]

Re: nissan 3.5 spark plug gap

Hey Rick ,<br /> The 1.0 mm is the 0.04 . I can't get it to run but a few seconds at that gap . Would'nt the wrong gap cause it to run a little hot ?

 

[SCO]

Re: nissan 3.5 spark plug gap

I'm no spark plug expert, but have read you want the gap as wide as possible to expose more vapor to spark for a good instantaneous burn, and narrow enough to insure good spark. .2 inch is 5 times the specified gap. Hows your compression?<br />Also, looking at the gaps in the Bosch Automotive Handbook, they have std gaps of .7 to .9 mm battery ignition, .5 mm for small magneto engines, 1 mm for lean burn engines, .3 to .5 mm for high compression engines.

 

[fast525]

Re: nissan 3.5 spark plug gap

Thanks SCO ,<br /> I'll try it at .5 mm and see what that does . As far as compression it's strong when it's running .

 

[SCO]

Re: nissan 3.5 spark plug gap

I wasn't trying to say you should try .5mm, just verifying that the recommended 1mm per nissan is reasonable. If you get spark at .2 inch gap(aka 5mm), then you should get spark at the spec'ed 1mm. Cutting the gap down to .5 should not solve the problem. Do you have good compression on the pull? I still think it's compression. Maybe a stuck ring that can use some OMC engine tuner.

 

[fast525]

Re: nissan 3.5 spark plug gap

Set the gap at 0.21 (5mm) and it runs like a top. It would'nt run but just a few seconds At 1mm then it would act like you hit the kill switch , also it would'nt take the fuel as you increase the throttle

 

[SCO]

Re: nissan 3.5 spark plug gap

What plug are you using? I have one of these engines,new, and I can see if its the same tonight.<br />Maybe you have a mixture or gunk up problem. I'd clean the carb, check compression, make sure I had the right(and new) plug set to spec., and run OMC engine tuner through it(1st thing prior to regapping to spec. This might solve your problem) You obviously have a good magneto. If none of that works, then you start to worry about all the unusual things it could be.