120 case 140 block

tony120

Petty Officer 3rd Class
Joined
Nov 26, 2003
Messages
83
thanks for the help in the past. what i was wondering was if i bought a new 89 140 powerhead, would it fit onto my 89 120 unit? i think i read in a seloc manual that the blocks were the same but different bore/stroke? if it will fit, is it east to do? thanks
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: 120 case 140 block

in 89 both 120 and 140 were big bore loopers. the block assy will interchange. there is some differences in the reeds and carbs. if your looking at getting 20 free ponies give up. speed cost money. how fast ya wanna go :) <br /> good luck and keep posting
 

tony120

Petty Officer 3rd Class
Joined
Nov 26, 2003
Messages
83
Re: 120 case 140 block

well i tried. how far can ya bore them
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: 120 case 140 block

If your looking for performace, start first with boat, and engine set up. This will many times yield as good of results as more horse power. Are you looking for a performace gain, or does your 120 need replacement? What type of boat are you running?
 

tony120

Petty Officer 3rd Class
Joined
Nov 26, 2003
Messages
83
Re: 120 case 140 block

its a 18ft wellcraft center console.i just want some more pep out of it.the motor isnt tired.but nothing lasts forever
 

usedboats4u

Seaman Apprentice
Joined
Nov 26, 2003
Messages
46
Re: 120 case 140 block

IF YOU REALLY WANT MORE PEP OUT OF THIS ENGINE, PUT IN CARBON REEDS, STACKS, LOW COMPRESSION HEAD GASKETS. IT WILL GIVE YOU MORE SPEED, MORE LOW END, NOW IF YOU REALLY WANT TO GO FASTER, FIND A GOOD 175
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: 120 case 140 block

The blocks / powerheads are identical. Same port timing, same bore and stroke. Work with the set up for performance gains. That hull is not going to respond well to small torque increases. <br /><br />If you do have to rebuild it, use the pistons from the 93 and newer V6. And the rods too if you can. They are lighter and the motor will idle fantastic.<br /><br />Good luck!
 
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