1976 70hp Evinrude

[Orval]

1976 70hp Evinrude . 70673D
I have put many dollars and hours into this. I have cleaned carbs many times with new rebuild kits. New impeller, new fuel pump, tank, fuel lines, spark plugs, capacitor, all 3 coils, tested stator, trigger, powerpack. rejetted with new boyesen reeds,...
I always could get it to start...muffs or tank....never could get it to run if put into gear. Muffs or tank...same as when I bought it.
Compression was 100 on top 2...95 on bottom...thought maybe I sheared the flywheel key....checked and no.

So...I pulled the powerhead and started tearing it down...cylinders and pistons are grooved badly...I believe from bad or wrong gas in the past. Machine shop is going to let me know this week if I need to get .030 or .040 oversized pistons in the rebuild kit.

here is my question..when I reassemble and set the carbs for starting, I am supposed to start, put in gear in tank and set idle timing....2 years of trying (could never get into gear while running) has me very low on confidence... can someone please walk me through this procedure? Everything that I have read says to set idle timing..then WOT timing..and then adjust idle.

Way more money in this than I will ever get back....so I want to do it right...take care of it..enjoy it...and leave it to one of the grandbabies... if you know what I mean!?

thank you

 

[F_R]

I'd have to get the book out, but I don't think there is any "idle timing". But subject to correction.

While you have that thing apart, make sure you check the baffle plate between the exhaust cover and cylinder block. They are notorious for warping in the area of the exhaust ports, then the gasket will leak and spray water into the cylinders, through the ports. That may be what killed yours.

 

[racerone]

Timing will not change for the life of the motor !------Unless someone fiddled with it .-----Even after re-assembly the maximum timing advance will be correct.----You need to understand that idle ignition timing is the point where throttle opens and it is a linkage / carburetor adjustment.----Make sure you read the correct manuals too.

 

[Orval]

Thank you.
would it be okay to sand smooth the baffle plate..flat of course...and can you easily sand too much of it?
All 3 plates?

 

[F_R]

Let me first say that there have been several changes in that area and I am not up to date on them. But it is the thin plate that gives all the grief because it is so thin in that area and not well supported on the other side. Worse, it is No Longer Available. As with any other part it has to be flat. You will have to evaluate it once you get it apart to see if it is salvageable.

 

[Orval]

I have it apart. Looks old..of course. How do I know if it is okay?

I have a 65hp that actually has the same carbs, reed boxes, thermostat, etc. that I got for parts about a year ago for $50 (came with a 90hp VRO rude with a cylinder blown). They just wanted out of the yard. Should I take one from it? I say that because if it was that plate, …….

How do I know if they are good ?