140 Looper to V6 Conversion?? Is it possible??

Stephan_from_Oz

Recruit
Joined
Dec 10, 2011
Messages
1
G'day from Down Under,

I have a 16ft Bullet that I am in the process of restoring. Current there's late 80's model Johnson 140 V4 Looper that meet a sad demise. I was wondering if it is to easily screw a V6 powerhead in its place and if so, is there any pitfalls that I should avoid. Ideally +200hp would be great. The boat performs well with the 140 however the additional horsepower/torque wouldn't go astray.

Thanks everyone for your advice.

Cheers,
Steph
 

samo_ott

Vice Admiral
Joined
Jun 18, 2006
Messages
5,125
Re: 140 Looper to V6 Conversion?? Is it possible??

Sounds highly unlikely to me but I'm not an V4/V6 expert. Others will reply. Easy way to tell is to look up the parts diagrams for both and compare the base (exhaust) gaskets to see if they are the same. Again, highly unlikely.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 140 Looper to V6 Conversion?? Is it possible??

The lower unit (gearcase) for the V4 looper is different from a V6 looper. (exception:For one year only-both 85 V4 loopers used V6 lower units.) Problem is that any of the V4 lower units use different gear ratios than a V6 gearcase. (including the 85's) Also, looks like the powerhead base gasket is different between the V4 and V6-which means the powerheads are not identical on the bottom.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: 140 Looper to V6 Conversion?? Is it possible??

Change the adapter plate,tuner,add correct lower unit(gear ratio and crankshaft length)and it will work, be a lot easier to just slap the complete 200 on it. That boat would really perform best with a 175 60? Johnrude as it a whole lot lighter than the 200.
 
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