Johnson,Evinrude V4 90-140HP

[j140head]

I have a good j140 block 1984 (crossfllow V4) can I use any V4 crankshaft 90-140HP , 78-95? also what is the difference in heads in a 90 vs 140. Does the additional HP come from bigger carbs and more compression from the diffferent heads. Last but not least should I only use the pat numbers in the service manual. Thanks for any help!!!

 

[Chinewalker]

Re: Johnson,Evinrude V4 90-140HP

DHadley is the crossflow guru here. He described some of the differences for me a couple years back when I was in a similar situation. There are several different crankshafts that can be used, but there are conditions. Some use different bottom main seals, so you have to keep the correct bottom main bearing carrier/seal assembly with the crankshaft in order to use them, .ie if you use a 1993 crankshaft, use a 1993 bottom seal/bearing.

Not a whole lot of difference in the heads - I was told they could interchange with little effect. Key is to keep them matched - casting numbers one off from each other.

The extra horsepower comes from bigger carbs, bigger ports, and bigger exhaust. 140s have what is referred to as a "bubble back" exhaust, which is essentially a tuned expansion chamber that extends beyond the normal flat back exhaust plate.

There is a lot of mixing and matching that can be done with the crossflows you mention - some is trial and error - some can be found through some board searches here on iboats. Lots of folks trying to get their 85s and 90s to go like 115s and 140s...
- Scott

 

[wilde1j]

Re: Johnson,Evinrude V4 90-140HP

2x!

 

[wilde1j]

Re: Johnson,Evinrude V4 90-140HP

You can't use '85 and newer 120/140HP BC they are loopers. Not sure about earlier matches.

 

[Chinewalker]

Re: Johnson,Evinrude V4 90-140HP

Yep, in 1985 they introduced the blooper V4s, and re-rated the 140 crossflow to 115. Same motor, just rated at the prop instead of the powerhead...
- Scott

 

[ezeke]

Re: Johnson,Evinrude V4 90-140HP

DHadley's entries in this thread will probably help:http://forums.iboats.com/showthread.php?t=233470&highlight=block

 

[iwombat]

Re: Johnson,Evinrude V4 90-140HP

140 heads are high-compression heads.
They also had the bigger carbs, different filler blocks, and bubble back exhaust as mentioned before.

 

[j140head]

Re: Johnson,Evinrude V4 90-140HP

Ok, I believe what you are all saying is that most V4 crossflow internal parts (ie. crank, rods and pistons)parts are interchangeable as long as you have the correct crank seal assembly for your model year as long as you match large or small split center bearing crank to the block. Do I need to use the original upper and lower crank bearing assemblies from my block or do I use the bearing assemblies with the correct seals assembly for my block from a crank I purchase. I also take it that you should use all of the original carbs and intake to the supply the needed fuel as well as the original flywheel and ignition components.
You are also saying that HP output of my 1984 140 is the same as a 1995 115 because the HP is rated at the powerhead vs the prop for later models.
What are your thoughts on after market pistons Vs OEM.
I just want to say thanks for all of your help, it is greatly appreciated!!!
Thanks, J