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Need some info about Johnson 300 v8

Norwegian Twister

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I have always wanted one of those engines, that sound. But are they worth to have ? Its a 95, they say its tuned to 380hp. But what do i need to do if i want to really build a beast out of it ? Where can i buy parts ?

I allready got a 300x and some 250 etecs, this is going to be a 5 trips a year engine
 

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Riverbound

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stock and we’ll taken care of great motors. modified was hot or miss and reliability was an issue. our first hot rod stoker with a built v8 the boat was named “when it runs”

our current with stock and just second effort heads runs flawless. and has been super reliable.

parts are VERY hard to come by and electronics are becoming an issue as well now.
 

Norwegian Twister

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stock and we’ll taken care of great motors. modified was hot or miss and reliability was an issue. our first hot rod stoker with a built v8 the boat was named “when it runs”

our current with stock and just second effort heads runs flawless. and has been super reliable.

parts are VERY hard to come by and electronics are becoming an issue as well now.

But some of them are crazy fast ? What do i need to do to waken up the beast ? Its just going to be a 5 trips a year engine and then i want total madness that scare the shit out of me. I want to try it on my procat 18, its going 96mph with a 250 etec, the record with this boat are 107mph with a 300xs, i wanna beat those mercury guys with a omc

I have a argo23 with a 300x, it will run around 120mph with that engine, but can i get it faster and more crazyness with this monster engine ? A new 450r or 500r is way out of my budget. A friend of me got a 115mph argo21 with a 300promax, then you know the drill, want next level :p

What are the secrets to get it crazy fast ? Nitrous ? Hahaha
 
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HST4ME

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No problem with parts, much of it all is available aftermarket. They are just two v4 loopers stacked up.


Monty builds some pretty nutty V8s



 

Norwegian Twister

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He got mail :) but i want a crazy offshore engine, not a drag engine. Cruise around in 100mph 2-3ft waves, then come to a flat area then just floor it and be scared as hell. Those 500 bucks in fuel for a hour trip 5-10 times a year is totalt worth it. When i allready got a everyday cat thats going 100 when its perfect condition with a 250 etec, but going 90+ all day long, 7 days a week
 
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HST4ME

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Gordy has been building OMC's for a loooooong time. He can take care of whatever you need
 

Norwegian Twister

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Gordy has been building OMC's for a loooooong time. He can take care of whatever you need
I sent him a email and asked alittle, showed him this threat and my other boat threat, so he know what kind of boats its going to be used on.

If it was a evinrude, i would make a monster alien cowl and name it Evilrude and just a big v8 sign in the back. Here i just tested one of my merc 3L cowlings on a etec 250, measured where to cut and where i need to modiefie if
IMG_20230722_195324.jpg
 
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Markus

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Monty, Al Stoker and Evolution Marine were the go-to guys for OMC V8s. Now, only Monty is left.

My advice: unless you live next to Monty's shop, stay away.

The OMC V8 was a huge failure. The manufacturing quality was terrible with bad castings and junk electronics seemingly assembled by blind, drunk people. Everything breaks. Transom brackets, ignition components, you name it. OMC had to sell them at a huge discount through the back door through Second Effort to be able to move them out the factory doors.

I've had a few friends who have had them for the same reason you want one. They did not keep them for very long. One friend tried to keep two alive on an offshore race boat. That cost him a lot of money.

I also knew a dealer who sold more of them than anyone else in Sweden. That means hundreds. Unfortunately, there were customers close to his summer house. They knew where to go when their engines broke down.

If you want to go fast, get another Mercury.

If you want something exotic, get a modified 300 HPDI.
 

Norwegian Twister

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Monty, Al Stoker and Evolution Marine were the go-to guys for OMC V8s. Now, only Monty is left.

My advice: unless you live next to Monty's shop, stay away.

The OMC V8 was a huge failure. The manufacturing quality was terrible with bad castings and junk electronics seemingly assembled by blind, drunk people. Everything breaks. Transom brackets, ignition components, you name it. OMC had to sell them at a huge discount through the back door through Second Effort to be able to move them out the factory doors.

I've had a few friends who have had them for the same reason you want one. They did not keep them for very long. One friend tried to keep two alive on an offshore race boat. That cost him a lot of money.

I also knew a dealer who sold more of them than anyone else in Sweden. That means hundreds. Unfortunately, there were customers close to his summer house. They knew where to go when their engines broke down.

If you want to go fast, get another Mercury.

If you want something exotic, get a modified 300 HPDI.

Damn, the answer i diddent want to get, but the harsh truth. Maybe i just say its enough with the 300x thats allready on the Argo23
 

STV_Keith

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Had a pair of Monty V8's on my Scarab. Monty's work was great. 380hp at the crank. Broke gearcases frequently. Switched to Merc 2.5 lowers, still broke, but not as frequently. The hot ticket is to use the 3L Merc lowers, they are supposed to be more reliable, but I never did it myself. Motors ran great for 8 years, sold them to a guy in Sweden, they went on some little 23' Fjording deal and then disappeared.
 

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Norwegian Twister

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Had a pair of Monty V8's on my Scarab. Monty's work was great. 380hp at the crank. Broke gearcases frequently. Switched to Merc 2.5 lowers, still broke, but not as frequently. The hot ticket is to use the 3L Merc lowers, they are supposed to be more reliable, but I never did it myself. Motors ran great for 8 years, sold them to a guy in Sweden, they went on some little 23' Fjording deal and then disappeared.
Its a guy in Norway, that has a fjordling 21 with 2 of those, i guess its him
mannes_full.jpg
 

STV_Keith

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Norway, that's right. Arne was his name. From what I've read, he sold the boat and the motors were removed by the next owner.
 

Norwegian Twister

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Norway, that's right. Arne was his name. From what I've read, he sold the boat and the motors were removed by the next owner.
Its just a couple years since that picture was taken, i saw alot picture's of that boat a couple years ago.

I think he own a Marina and these days he drives in offshore 3c with a twister24

I dont have a Facebook profile, but i guess its some pictures of the boat on this page

Screenshot_2023-11-17-22-00-05-606_com.android.chrome.jpg
 
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HST4ME

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Gear cases on anything when you run the shit out it is the end of the line. V8s carry a huge rotating mass. 2.5 s are the easiest to keep lowers under. Under a refrigerator I'd do a 3à and it wouldn't be hard to do a floppy vane pump on.

Dude wants to build a selective use motor, cool.
 
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Norwegian Twister

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I have a couple 3l sportmaster extra, so i still thinking about this engine 23 hours a day, but Monty havent answered me yet :/

I love to build things the world aint ready for yet, a procat18r with a v8 is one of those things :p i'm going to rebuild that boat this Winther anyway, so why dont have a refrigerator on the back ? This is with a "small" 250, 3.3L v6, the v8 would look insane on that little thing
IMG_20220501_182932.jpg
 

STV_Keith

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You're going to want the shortest mid you can get if you plan to put a V8 on that thing. Start looking for a 6-12" OMC race mid/clamp. Good luck.
 

HST4ME

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Many more f1 mids in Europe than over here.
 

Norwegian Twister

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You're going to want the shortest mid you can get if you plan to put a V8 on that thing. Start looking for a 6-12" OMC race mid/clamp. Good luck.

I know, but i just wanna beat the 300xs guys with a Johnson engine :p 1 trip is enough on the little 18feeter :p haha
 

STV_Keith

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Should be able to do that with a V6 that's been worked on, and those are going to be easier to find. Plus Monty doesn't hate working on those as much as the 8's.
 

Norwegian Twister

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I dont have Facebook, but the v8 is already in Norway. But i have thinked alot on that engine the last weeks, maybe its better to just use the 300x instead of buying that big, old, thirsty v8 that going to have alot of problems. They are talking about 10k usd in Norwegian kroners
 

skydog

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I would stay away. Age, part's ect ect
 
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