1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

[HappyOurs1]

I recently purchased the above motor. Model# 70ESLR74M

Work Done:
Water Pump (Impeller) Rebuild kit Installed
Changed Gear Case Lube
New Plugs (Installed New Champion UL77V) Previously NGK Standard type plug
Carburetor Tear Down & Rebuild (All components looked clean and as new compared to new kits that I purchased)

Engine seems to run okay, With New Plugs, Gas /oil, etc, Idles better with the new plugs, but does stall if left to idle for more than 5 seconds probably due to low rpm's.

My concern is that Power seems to be lacking, I dont have a tach hooked up yet... but have a digital pickup for my next trip out. But I would think its not reaching full rpm's. The engine is powering a 16ft Tri-hull @ WOT gets me about 25mph or 45kph.... is this normal or should there be more?

Thanks to those that respond

 

[63Sport16]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Love that boat you have. Getting it up to 25mph with a 70hp is pretty good. Sometimes the motor is over propped and doesn't idle great. I'd check to see what prop is on the motor and compare it to what the factory recommends for that size boat , motor and load. Optimal RPM's are between 5200 and 5800 WOT.You can also try adjusting the idle up a little bit. In gear idle should be between 550 and 650 RPM.

 

[BonairII]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Are you sure that your boat isn't waterlogged? That would def slow you down.

My 1977 75hp Evinrude pushes my 16' Aluminum Starcraft 35mph (17p prop).

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Thanks for the replies,

What is the best way to gauge if the boat is water logged? Its in factory like condition from what I can tell. Floor is Fiberglass, possibly over wood. There is only one spot where wood is exposed (Up front, port side, under the dash) but didn't look wet!

The floor paint thinned out pretty good after a power washing. In the water, it drafts to right around the goofy red paint line on the hull. I haven't seen a good place to inspect under the floor, & when I get some proper tie downs I will take it for a trip to get it weighed. From what I read earlier on the Boat... it should weigh around 900lbs dry.... motor and gear extra.

I believe I will adjust the idle up a little to get her to keep running after putting her in gear.

Thanks

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Anyone Know if this engine has Variable timing? Does it change the timing from Idle to WOT? Maybe point me in the right direction to 2 stroke timing setup and proper advance for my engine Model # 70ESLR74M

Thanks

 

[63Sport16]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

That boat appears to be a 1965 or 1966 custom Evinrude . It is a fiberglass boat which has a plywood framing under glass. It's a GullWing design and it is a heavy boat. Mine is a 1963 Sport 16 Evinrude and it weighs in around 880 lbs. With the original 75hp V-4 it would get up to 26 mph using a 10 x 9 1/4 P prop @5000 RPM. Using a 10 x 12 it would drop to around 22mph and @4200 RPM. The RPM drop indicated over-propping for the load.

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Thanks for the reply 63Sport16 Yeah My Boat is a 1964 Evinrude Sweet 16. From what I remember... the guy at the boat shop showed me the prop & how to read it.... I thought it was 10 1/4? x 15 or 17pitch. I will try later this week to determine the max rpm and boat speed achieved & maybe look at lower pitch prop if the rpm's are not reaching close to max.

 

[63Sport16]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

No Problem. That pitch seems a bit high for your boat. Good to see it is a 1964. You should decide if you are gonna just cruise it or use it for pulling/hauling heavy loads. I put a 1973 135hp Ev. with a 13 3/4 x 15 P on mine and it scoots pretty good upto about 48mph with just me in it. Got to watch the hole shot though, it will try and bury the transom and put you looking at the sky. Good luck.

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

So the Specs on my prop... Its a 13 1/4 x 17. So now I'm thinkin... probably guna be hard to pull skiers & tubers this summer unless I trade up or get a bigger motor. Hope the weather here holds out & some parts I ordered arrive & I may be able to get it out on the lake & check the RPM's later today.

 

[BonairII]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Dropping to a 15p will give more holeshot/torque for tubing. My 17p prop is a nice overall prop, but I have a 15p for better holeshot/torque for when we start pulling tubes.


Having a working tach is key though. Once you get that working, you'll be able to prop your motor correctly(instead of guessing).

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Well sounds like I will have to do some local Prop Shopping. I cant seem to locate a reasonably priced long term Tach... So I will be testing with my portable, digital, tach counter to determine Max RPM in the calm, Put the Cover back on & listen carefully to the Sound of the Engine, & Watch my phones GPS for speed. That should give me some idea where I'm @. If I can Locate another Lower pitched prop... i will give that a Try and Re-test till I determine the Engine RPM's are in the appropriate range. Then If all goes well, try pulling a Tuber or Skier. Wish me luck... or would your opinion be that 25MPH may not be enough speed for such fun?

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Okay so I got her out this evening. Top Speed was 47kph @ 4350 RPM with just me a the Girlfriend.... Should I down size the prop to a 15 pitch as I will probably be using it fully loaded 4 ppl & gear?

 

[63Sport16]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

I would drop the pitch to the 15. If the motor is timed in and running good you should hit the 5k rpm easily now. You should still be in the 23+ mph range.

 

[eavega]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

I cant seem to locate a reasonably priced long term Tach...

Look on e-bay for a used tach. I picked up a Faria tach for that same motor (basically anything with a 6P setting) for under $40. There is an online store that I purchased a no-brand outboard tach for $30, but that one failed after two years. You get what you pay for, I guess.

Would your opinion be that 25MPH may not be enough speed for such fun?

Depends on who you are hauling. My boat has a top speed of about 32 MPH with 4 aboard plus gear. When I pull a tube, the younger kids seem to be getting a good thrill with the boat going less than 20 MPH. The older kids will dare me to go faster, but none have stayed on if I am doing more than 25 while carving turns. I have never tried to pull a skier, although I would suspect that its more a matter of getting up to speed quickly more so than your top speed.

Your motor is definitely not running in its happy range, so you should drop the pitch on the prop to 15. I run a 70 HP Johnson on the back of my 15' fiberglass trihull and it doesn't seem to be nearly as large as your boat. I don't get my motor up to correct WOT RPM with a 17P aluminum prop (I do with the 17P Stainless, though) if I am loaded down.

Rgds

 

[BonairII]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Not sure about a 1974, but my '77 75hp has a range of 5300-5800rpm. If yours is the same....then you are currently lugging your motor at 4350rpm.

Just bite the bullet and spend the $60 bucks or so on a tach. I bought my Teleflex tach for around $60, I believe. Screwing around with a portable tach is going to be a pain in the arse.

An accurate tach will help you find the correct prop more quickly, and pay for itself in gas savings alone.

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

I believe. Screwing around with a portable tach is going to be a pain in the arse.

I can Understand that.... Right now I am on a Tight budget, i was able to borrow a hand held Tach that picks up a reflective dot on the flywheel for base line purposes. I can check a couple more times with a 15 prop & get another baseline with which to gauge compared to my gps speed. Don't get me wrong, I will get a Proper tach eventually... maybe later this season or next season.

I've read & heard alot about Seafoam Products recently.... Do you recommend using them? Reason I ask.... i thought I seen some whiter smoke than I remember the first time out.... havent had a chance to check the plugs, or inspect the pistons since my run lastnight.

 

[busted-bayliner]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

i have a 74 70hp motor also i also have a 65hp envinrude on a 16 ft tri-hull my prop on both motors is 13 1/4 x 17 an me im 245lb the wife and 2 kids and a friend last time i was out plus gear i was at 32 33 mph an that a 65 hp sounds like something is amiss with your 70

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Does anyone here have Engine Specs for a 70ESLR74M? I'm Looking for Operational & Max RPM's, Max torque & @ what RPM.... any other useful or relevant information?

 

[HappyOurs1]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

Okay... thank you to eavega Your information is & will be very useful.

Update... I performed a compression Test on my motor. 149psi -151psi cold & with WOT.
I thought that to be a fluke since many have suggested anything over 90psi is okay so long as the compression was fairly even. So I fired it up and let it run for 10 min with muffs on. Tested again and got an even 150psi on #1 &2 & 151psi on #3 cranking for a three count.

Also I have been lent a 13 3/4 x 15 prop to test hopefully later today or tomorrow. Hoping for a better whole shot & a less lugging the engine down, still wondering if it can pull a tuber or skier.

 

[jimmbo]

Re: 1974 Johnson 70Hp Power Shift 2 -Loop Charged Motor Specs

View attachment 154555You boat is Junk. Ship it, with motor and trailer to me, prepaid freght and I will dispose of it for you, free of charge. My dad had a 1964 Sweet 16 with a 1965 90hp. It did about 30mph using the 10 X 9 1/4 prop. It was and still is my favorite boat.

Pop Science mag tested it
http://www.popsci.com/archive-viewer?id=_iwDAAAAMBAJ&pg=136&query=evinrude sweet 16

1974 70hp
49.7 cubic inches
70hp @5000rpm
WOT rpm range 4500 - 5500
Lower unit gear 12:29
Hydro assisted shift with positive mechanical follow thru.

17 inch prop does not sound out of line for that boat. Do you have power trim? If not, what hole is the tilt pin in? should be second or third one out
Sheck to see if the throttle is properly adjusted to make sure that when the control is widw open so is the timing plate and the carbs are fully open.
Just put it on a flatbed, send it to me and never worry about it again