140hp crossflow

[Jmr1974]

I picked up 1980 140hp crossflow in decent shape for next to nothing, perfect compression, spark etc. the lower unit is uglier than I like, I found a 115hp crossflow I can get cheaper than a clean gear case, not sure if it runs or not(don’t care if it does) the lower is in nice shape. Im thinking this should bolt up to the 140, is my thinking correct and is the gear ratio the same? Thanks.

[Paul Vaillancourt]

I picked up 1980 140hp crossflow in decent shape for next to nothing, perfect compression, spark etc. the lower unit is uglier than I like, I found a 115hp crossflow I can get cheaper than a clean gear case, not sure if it runs or not(don’t care if it does) the lower is in nice shape. Im thinking this should bolt up to the 140, is my thinking correct and is the gear ratio the same? Thanks.

It will depend on the years of the motors, some time in the 1990's the drive shaft length changed and got longer. The gear ratio will be the same.

[Jmr1974]

It will depend on the years of the motors, some time in the 1990's the drive shaft length changed and got longer. The gear ratio will be the same.

cool, I think the 115 is within 1 or 2 years either side of the 1980 I have. It’s definitely not into the 1990’s. Thanks

[Jmr1974]

So I did end up picking up the 115hp. the women I got it from new nothing about it just wanted it gone. I didn’t care if it ran or not I just wanted it for the lower unit. Just for the hell of it I threw the compression tester on it, 120 psi on all 4, then I checked for spark, good on all 4 again. I had no idea what year it was, I just new it was a crossflow from the pic the women sent me. So I checked the number on the aluminum plug on top of the block, ends up being a 1980 just like the 140 I have. I’m going to use the 115 as a parts motor for my 140. I’m assuming I can use just about every thing of it if I ever need to. Starter, coils, stater, trim pump,carbs, etc etc etc….. aside from it not being a bubble back I’m wondering if the block is identical, to the 140??

[MrG]

The blocks are the same it’s just the tuner in exhaust of the block isn’t threaded for the adapter inserts. Bigger carbs are on the 140 if you remove the 140s exhaust bubble you will notice the half ass relief made for the exhaust in the block where the bubble dumps back in they did a plunge cut it needs to be blended in for the flow upside Down U it’s worth some horsepower with a pair of reeds it will run strong

[Jmr1974]

The blocks are the same it’s just the tuner in exhaust of the block isn’t threaded for the adapter inserts. Bigger carbs are on the 140 if you remove the 140s exhaust bubble you will notice the half ass relief made for the exhaust in the block where the bubble dumps back in they did a plunge cut it needs to be blended in for the flow upside Down U it’s worth some horsepower with a pair of reeds it will run strong

Thanks for the info, I’ll plan on doing the things you mention. The 140 is going on a Ventura that I’m in the middle of restoring.

[LakeFever]

These things are bullet proof if you run ethanol free fuel and premix your going to have a hard time blowing it up

[Jmr1974]

These things are bullet proof if you run ethanol free fuel and premix your going to have a hard time blowing it up

Yes sir, I have a gas station right down the road that has 2 ethanol free pumps with 91 octane.

[LakeFever]

One other thing youll want to check is the numbers on the heads. Im not sure what year OMC changed them but its right around 80. I know the 79 140’s came with some very tight heads that dont kine todays low octane fuels. Mine was an 83 bought new in 84 and it had the lower compression heads on it. I ran 91 non ethanol whenever possible but many many tanks of “mid grade” marina gas were run through that motor. I spun it up over 6k every time out and i sold it a few years ago. Great engine, although these are on the thirsty side. I fogged it down and changed the lower unit fluid at the end of every summer and replaced hoses, power packs, and the rectifier. Those were the only issues I ever had with it and none of these left me stranded. When the power packs went it lost about a thousand rpm and was lazy out of the hole.

sst and raker props are the way to go

[Jmr1974]

One other thing youll want to check is the numbers on the heads. Im not sure what year OMC changed them but its right around 80. I know the 79 140’s came with some very tight heads that dont kine todays low octane fuels. Mine was an 83 bought new in 84 and it had the lower compression heads on it. I ran 91 non ethanol whenever possible but many many tanks of “mid grade” marina gas were run through that motor. I spun it up over 6k every time out and i sold it a few years ago. Great engine, although these are on the thirsty side. I fogged it down and changed the lower unit fluid at the end of every summer and replaced hoses, power packs, and the rectifier. Those were the only issues I ever had with it and none of these left me stranded. When the power packs went it lost about a thousand rpm and was lazy out of the hole.

sst and raker props are the way to go

I’ll check the head numbers tonight. As far as fuel consumption goes it’s gonna be better than the 235 crossflow I was going to put on my Ventura,probably way better. I had a Valero with a healthy 1985 175 Mariner on it, how would the crossflow 140 compare to the 175 V6 Mariner for fuel consumption? Granted I was always on the throttle in the Valero, can’t put a price on fun. Also the 140 is around 100lbs lighter than the Johnson 235.

[Jmr1974]

Lake fever, I have a couple raker props that came with my 235, just gotta check that their diameter isn’t to large for the 140, I also have a 28pitch chopper I think is right 14” if the motor will turn it?? Of course if these props would fit I’ll have to get them rehubbed.

[MrG]

Keep the build light 1/2 nidacore floor 1708 one layer on both sides stronger than ply put a back up plate for seat bolts cusa 1 in board for transom you could save 300 lbs quickly without wood stronger lighter Never rot my thoughts

[Jmr1974]

Keep the build light 1/2 nidacore floor 1708 one layer on both sides stronger than ply put a back up plate for seat bolts cusa 1 in board for transom you could save 300 lbs quickly without wood stronger lighter Never rot my thoughts

Actually I have another thread going in the boat build ups and restoration (1977 Ventura build). The boat was a comp hull when I got it ( completely rotted) for the core I used core cell and coosa for the transom. 1/2” plywood floor. I also added big knees to the transom made from coosa. I didn’t want to be tripping over exposed stringers so I put the floor in over them. Also built a rear seat that will be removable for when I’m by myself. Just a wild guess but I think it’ll be around 200#s heavier than the original comp hull.

[Jmr1974]

One other thing youll want to check is the numbers on the heads. Im not sure what year OMC changed them but its right around 80. I know the 79 140’s came with some very tight heads that dont kine todays low octane fuels. Mine was an 83 bought new in 84 and it had the lower compression heads on it. I ran 91 non ethanol whenever possible but many many tanks of “mid grade” marina gas were run through that motor. I spun it up over 6k every time out and i sold it a few years ago. Great engine, although these are on the thirsty side. I fogged it down and changed the lower unit fluid at the end of every summer and replaced hoses, power packs, and the rectifier. Those were the only issues I ever had with it and none of these left me stranded. When the power packs went it lost about a thousand rpm and was lazy out of the hole.

sst and raker props are the way to go

lakefever, the head numbers on my 140 are 326502 (left side) 326503 ( right side)

[Jmr1974]

This might be worth picking up for a parts motor, I think this is 1970’s 135 that have the tight heads and big carbs guys mention. Not sure how many years OMC made the 135 that had those parts?? What do you guys think?