1977 140hp block on a 1978 85hp mid

[bishopcherrycoke]

Good morning folks! I just picked up a 1977 140 hp Johnson block. It needs a bore and rebuild but I am planning on putting it on my 1978 85 hp evinrude motor. Before I sink any money into the 140, does anybody know if it will bolt right onto the 85hp? From what I gather the 85-140 use different powerheads but mids and lower units are the same. The exhaust tuning is different too I believe. Will this work? Is it a hp difference or are the years different? Thanks for the help.

 

[Bob_VT]

Re: 1977 140hp block on a 1978 85hp mid

Okay..... The exhaust is different since the 140 uses the "bubble back" and has some passages milled in. The ports are a hair larger and more squared off in the 140 block. The powerhead will bolt right up.

Yes it will fit the lower unit.

To obtain the proper 140 hp you will need the reed valves, and carbs too.

Now the 1978-79 models are rated as head horsepower so...... a newer 1985 and up are prop rated. If you encounter an older 140 that is head rated and come up to a newer 130 HP which is prop rated......you loose that race

Yes, the V-4 is my favorite block. You will need to hunt down the carbs re-do the reeds to make sure they are up to snuff and with the 140 powerhead.....yes you have a 140.

With the proper parts and assembly you actually end up with about a 125 HP prop rated motor......... the v-4's are great motors but thirsty motors too.

 

[bishopcherrycoke]

Re: 1977 140hp block on a 1978 85hp mid

Thank you for the reply Bob. I am sorry, I should have been more specific. I got an almost complete 140 powerhead. (Not just a block) It has the bubble back exhaust installed, I have 2 carbs with the bigger throats, I believe 1 3/8". My 85 I believe has the 1 1/4 or 1 5/16 not sure. I also just ordered on eBay a 1977 140 intake manifold with the Reed cages installed. I will use the fly wheel and electronics off the 85. They have unlimited power packs so that should work one the 140. The 85 mid will take some power away due to the exhaust being different. Just as long as this new 1977 140 powerhead will bolt to my 1978 85hp mid/lower unit.

I agree, I have grown quite fond of these crossflows. Parts are cheap an easy to come by, they have been crazy reliable(for me) and mine have always run better than friends I/O boats. But you are right, they are thirsty little things.

 

[Faztbullet]

Re: 1977 140hp block on a 1978 85hp mid

It will bolt together but the megaphone and can are different on a 140, you will need to change these to get the full performance of of the 140. If you dont have the reed stuffers and 140 carb dont worry about it,just assemble and it will be a strong 110-115hp motoor

 

[bishopcherrycoke]

Re: 1977 140hp block on a 1978 85hp mid

I do have the intake stuffers, but what is the can and megaphone?

 

[V153]

Re: 1977 140hp block on a 1978 85hp mid

Hate to burst yer bubble but a '77 powerhead won't bolt onto a '78 mid. That was the year the bolt spacing changed.

Forgive my crude drawing. '78 & up is on the left, pre '78 on the right.

 

[V153]

Re: 1977 140hp block on a 1978 85hp mid

For example:

 

[bishopcherrycoke]

Re: 1977 140hp block on a 1978 85hp mid

NOOO! That sucks. I thought I got myself a new motor. Well, thanks for the pictures. They are close. Is there anyway to "massage" it to get it to fit?

 

[emdsapmgr]

Re: 1977 140hp block on a 1978 85hp mid

Looks like the power head base gasket is the same for both engines. They changed the bottom of the block when they went to the dual thermostats at the exhaust adapter in 1977 and later engines. The powerhead should fit. Here's the rub. The lower units shift differently. The 77 shifts backward from the 78. You'll have to change the 1978 front intake manifold back to the 77 in order to use the belcrank assembly so that it will shift correctly. The 77 140 is the only crossflow that had a megaphone (exhaust tuner) under the exhaust adapter. A real performance setup!

 

[V153]

Re: 1977 140hp block on a 1978 85hp mid

Is there anyway to "massage" it to get it to fit?

Not sure the old 'start the screw sideways' trick'll work in this case. As you can see from the pics they don't give ya a lotta extra meat to work with. I spose a welding/machine shop could put some material where it didn't used to be but I dunno.

I feel yer pain. That '75 115 block my buddy mailed from Minnesota is near mint condition. BUT it won't fit any of my mids. Dang!

 

[bishopcherrycoke]

Re: 1977 140hp block on a 1978 85hp mid

Oh well. It's not worth "rigging" I'd rather do it the right way. I'll go shopping again for a block. Do you know what blocks will fit? 1978 and up? Until they swithed to the looper?

Thanks for the info V153, you saved me alot of time and money! I really appreciate it.

 

[V153]

Re: 1977 140hp block on a 1978 85hp mid

Do you know what blocks will fit? 1978 and up?

Yes. '78 & up are purty much the same. However somewhere along the way (early '80s?) they changed the case & main crank bearing. Old one's were bout 2" in diameter. New is like 3 1/4". Not sure what year that occurred. Still use the same crankshaft btw, just the bearing is different.

There's not much changed from that design since it's inception in the late 50's. The block is the same from 85 - 140hp. The added horses come from bigger carbs, and exhaust mods.

I can tell ya from experience they're dang near bulletproof. Who d'ya think Yamaha copied their v4/v6 2 strokes from?