1970 18hp evenrude fast twin

[77kingfisher]

:lol::lol::lol: but also :Cry: and :mad-new:

Yes im dealing with a 2014 Lincoln MKT at work right now under warranty that's been neglected has 64k :joyous: on it and ford flat out told me to check the valve clearance. If that's out of spec look at nothing else and put a head and timing components in it :embarassed::facepalm::facepalm::lol::lol:!!!!!! Im like are you crazy that's 23.6 hours of warranty time at least. No relash the valves no no no put a head on. WOW throw away parts :lol: can anyone say I think its every ware.

Please no car comments. Or truck

 

[Chinewalker]

Ok would a say late 70s 25 power head bolt right up to my exiting O/B?

No, it will not. Late '70s 25 powerhead was the 31.8 cube version. VERY different beast. If you really wanted to make your motor a sleeper, you'd need a 22-cube 25 powerhead & carb. Easier still - find a 25 and slap your 18 cowling on it...

 

[racerone]

Post # 2 in this saga mention up to 1976 model year.

 

[77kingfisher]

No, it will not. Late '70s 25 powerhead was the 31.8 cube version. VERY different beast. If you really wanted to make your motor a sleeper, you'd need a 22-cube 25 powerhead & carb. Easier still - find a 25 and slap your 18 cowling on it...

So your saying the blocks of the 25s up to 1976 are the same as mine. But late 70s are the larger displacement. And I like the cowling idea but i have a source for powerheads only. Hmm time to track one down. The reason im wanting an extra nudge is this motor is on my duck boat. As it sits right now I cant have any more weight on the transome. So more power same or less weight and im in. I like the little holes no one else can or is willing to go to . Bang Bang Bang... CLICK... NO! Hhh reload :lol:.

 

[Chinewalker]

Yes, that is correct. Stick with the 22-cube family and you can make your go-fast motor. Once you get the motor together, be sure to prop it to spin up. If your boat is loaded with decoys, a big four-legged buddy and other gear, you're carrying a heavy load. If the motor is over propped, it's akin to driving uphill, in overdrive, while towing an Airstream. Going to a lower pitch (if needed) is like downshifting to get back into the power band. Prop it to spin into the upper end of the range given above and the motor will be happy.

 

[racerone]

THese 25 hp models were very popular.---Should not be hard to find one.---But make sure it is in good condition before handing over the cash for one.

 

[77kingfisher]

So let me ask this then whats a fair price for a 1970 25hp that needs a carb job and throws its self out of gear? Asking 499 for O/B 5 gal metal tank and spare prop. Im thinking like 250-300 max and ill mill the lower unit down at the neighbors. Rebuild the carb, decarb the motor, and put plugs in. Total out of pocket 400 max?? What are they worth??

 

[racerone]

Never heard the term ----" mill the lower unit down "-----What is the reason for it ?

 

[Chinewalker]

Never heard the term ----" mill the lower unit down "-----What is the reason for it ?

I think he's referring to the clutch dog needing to be re-ground. I've heard of folks doing that with mixed success, as the dogs are case hardened. If you take enough material off to square up the dog, you take that hardened layer off in the process. Some have told me the dogs will work, others say they wear quickly. Haven't done it myself...

 

[77kingfisher]

Never heard the term ----" mill the lower unit down "-----What is the reason for it ?

My neighbor has a small but well equipped machine shop. He has a top shelf mill that allows for the head to change its angle (from 90* like most mills) so at a slightly tighter angle say 86* or 85* this allows the clutch dog and gears to have a positive retention when in gear. And one key part I learned this the hard way mill it slow and keep it cool (as to not damage its hardness). I have tried straight 90* and ya that works for about 10 min or less. I milled my current 18 last summer and beat it like I hated it till the ice showed its teeth. So far so good but like chinewalker said mixed results. Kind of a roll of the dice I figured it wouldn't cost any $$$ so try it its already junk worst that can happen is I still have to buy new ones :lol:.