Tell me about my 1980 70hp Evinrude E70elcsa

[redfishsc]

I just bought a used bass boat (1987 Glasstream 1550) that has the 70hp 1980 Evinrude. Engine seems to be in great shape. Cold cranks very easy as long as you know to push the key in to activate the primer lol. Runs smoothly, idles fine.

This is the first large outboard and bass boat I've ever owned. I'm a cabinet maker and have also done truck cylinder head swaps and rear-gear swap/setup so I have some mechanical understanding. So anything you guy share I'll appreciate greatly.

Prop is a SS 13-3/8 dia x 17 pitch. Gets up on plane ok but has to be fully trimmed down (see below, engine is a 20" on a 15" transom). It handles fine, not as bad as you might imagine with a longtail engine.

The boat itself is in beautiful shape for such an old girl. It lacks any engine telemetry gauges so I'm buying a tach and would like to put temp gauge at some point.

I've ordered the Seloc and also OMC shop Manual for it.

Anyhow, I'm looking for the following info, and ANYTHING you guys can share that might be known problems with this engine.

Does this have an overheat alarm? Is this something that is a part of the control panel (throttle panel), or in the engine cowl?

Is there an hour meter buried in this thing somewhere?

This motor is unfortunately a mismatch. It's a 20" shaft on a 15" transom. Prop center is roughly 7" below pad. Can you guys suggest a budget, but trustworthy static jack plate? I definitely cannot afford a powered jack plate.


Would a whale tail/hydrofoil assist getting up on plane at lower speeds? I basically have to hole shot it at WOT but once it planes it will hold it ok at about 1/2 throttle which is my preferred cruising speed because of stumps.

 

[racerone]

There should be a warning horn in the control box.---Best to test it now.-------If you do not know condition or age of water pump impeller you should install a new one.

 

[redfishsc]

Ok, understood. I don't know how to test it. I'll look it up.

I've swapped impellers before on 6hp and 7.5 hp Johnsons so I assume this is similar

 

[redfishsc]

By the way I get no "beep" when I turn the key.

I'll see about locating the tan wire and grounding it out tonight to see if something buzzes.

 

[racerone]

The " beep " on the turn of the key was a feature on newer control boxes.-----Find the tan coloured wire at the cylinder head.-----Slide rubber boot to expose knife connecter.----Turn key to on.-----Touch wire connecter to ground.----The horn should sound.

 

[redfishsc]

Got it. I will do that tonight.

I eventually would like to put a temp gauge up for this. After I cracked the cylinder head on my Vortec 5.7 in my truck from overheating I've become a bit of a temperature freak.

 

[flyingscott]

Put up a pic of the back of the boat. The propshaft 7" below the pad sounds right. Shaft length is measured from the transom hook to the cavitation plate, not the prop shaft. Exhaust cover gaskets like to leak on that motor, look for water intrusion in the cylinders. Normal to be trimmed all the down for best holeshot. Forget the temp gauge and put a water pressure gauge on the motor instead. Prop the engine to turn 5500 rpms with a light load.

 

[redfishsc]

Put up a pic of the back of the boat. The propshaft 7" below the pad sounds right. Shaft length is measured from the transom hook to the cavitation plate, not the prop shaft. Exhaust cover gaskets like to leak on that motor, look for water intrusion in the cylinders. Normal to be trimmed all the down for best holeshot. Forget the temp gauge and put a water pressure gauge on the motor instead. Prop the engine to turn 5500 rpms with a light load.

I'm holding the tip of the stick rule at the transom hook.

Tip of the skeg/keel is nearly 15" from the pad.

 

[racerone]

Looks correct to me -----A long shaft motor on a 20" transom is what I see.

 

[ct1762@gmail.com]

looks fine to me transom-wise. thats about were you want the cavitation plate to be for overall fishing/pleasure cruising. could certainly raise it up to the top bolt hole, but holeshot would suffer slightly. also, it looks like a 20'' transom, not a 15''. not many 15ft and larger boats were made with a short transom, even back then. pretty awesome it has a pad! could throw some real power on that hull and fly.
I'd certainly make sure the temperature is 125-152.5 degrees measured at the top of the cyl head at 900rpm. run it for a good 5 minutes to get it up to temp. you will find out well before then if it's overheating. if its 160+ degrees, take out the thermostat and throw it in a boiling pot of water to confirm operation and that it doesn't open "slugglishly" or better yet get a new one with new gaskets, and check to be sure the blowoff valve grommets are sealing those red plastic plungers. don't want those leaking! if it were mine, i'd take off the gearcase and do a full pump kit (OEM, not aftermarket).

 

[redfishsc]

I just pulled numbers. I leveled the boat (pad) and the cav plate. Pulling measurements from the concrete, the center of the prop is 8.25" from the pad.

I see a lot of banter about putting the center of the prop 3-5" from the bottom of the boat.

Either way I fish a LOT of 2ft deep water, I'm hoping I can raise this up some.

 

[flyingscott]

Your measurement means nothing. The important measurement is from the top of the transom to the cavitation plate. You have a 20" motor on a 20" transom nothing wrong there. That is what motors look like when they are mounted correctly.

 

[redfishsc]

Ok gents, I greatly appreciate the help. You've saved me a lot of headache!

I'm testing the overheat alarm now.

 

[racerone]

It has power trim and tilt.-----In shallow water you can raise the motor to clear the bottom of the river / lake !!

 

[redfishsc]

Also handy to bathe the guys that anchor right next to you up in the creek.

 

[redfishsc]

Ok the overheat alarm works loud and clear. Thanks guys!

 

[redfishsc]

Ok Gents I raised the motor up to the top hole. As you said, getting out of the hole is a bit more work and surprisingly the speed isn't any better. I have a Whale Tail that I've tried on and off over the holiday weekend and it definitely improved holeshot BEFORE raising the motor and after, the bow doesn't rise nearly as much.

I'm going to keep making fishing trips in some sheltered rivers until I find the motor height and use/lack of the hydrofoil I like the most.

Also the tach is installed and working. Things seem right. At WOT, trimmed fully down, RPM is about 5100. I can trim it up a bit and feel the boat plane out smoother and RPM goes up to 5500 or so.

 

[ct1762@gmail.com]

nice so at 5500 you should be right around 39-42 mph unless some major slip is going on

 

[redfishsc]

When not carrying much of a load other than me and my son (approx 400lb total) we topped at 38, but with tackle, second battery, and my 9 year old daughter we top out at 35.

 

[racerone]

Sounds correct.