Logo
FULL SITE MENU

1957 evinrude 7.5 hp ( just checked compression)

M

merkdawg

Contributing Member
If you've read my post before then you know the story of this motor. Bought motor, was running rough so I change plugs,point condensers and rebuilt carb. Still ran rough in barrell. Wouldn't rev up and alot of white smoke. Did compression test with the type of tester that screws in the plug hole. Now I got about 25 mabe 30 psi on both cylinders. Is this motor shot? or is it a head gasket? Someone help me out please? Thanks.
 
Re: 1957 evinrude 7.5 ( just checked compression)

Likely the head gasket blown -------right between the 2 cylinders , fairly common. -----Seen that many times.
 
Re: 1957 evinrude 7.5 ( just checked compression)

Hey thanks, thought I might give that a try. Would you happen to know the sequence order of tightening the head bolts and the torque specs?
 
Re: 1957 evinrude 7.5 ( just checked compression)

80 inch lbs--------------------Make sure the head is flat ( it will be warped )----------------Start in the center and work outwards .--------Tighten in 3 steps.
 
Re: 1957 evinrude 7.5 ( just checked compression)

thanks for the info. Will get back to you after I get the head off.
 
Re: 1957 evinrude 7.5 ( just checked compression)

Hey just got the head off this motor. Showed signs of water in there. Going to order a gasket tonight. Might have it on by next weekend. One other quick question? I have a 1990 evinrude 4 h.p. Deluxe.It runs on a 50:1 mix. Can I run my 57 evinrude on that same gas? or should that be 24:1? or 40:1? Thanks
 
No -----you do not even need lockwashers --------torque to 80 inch lbs ---------retorque after first run ( after motor cools )
 
Hey thanks. By the way found an old Apache on line for 20.00. The engine is froze. Is that motor made by clinton and can you still find parts? Just curious. Thanks
 
Hey racerone don't mean to question you,but are you sure about the 80 inch lbs. I have a torque wrench that is in ft lbs and had it set for 60 and I broke a head bolt. Am I using the wrong kind of wrench or just the wrong setting.Thanks
 
Hey again, you're saying 80 inch lbs? so if my torque wrench is in foot lbs then I would set it for about 6.5 lbs on my wrench correct? Thanks again
 
Hey thanks. Just got in from watching the UK and Carolina game. Go Cats. Since I live in KY. Thanks for the info. Will go out and get a new bolt tomorrow and put this back together. And I read your post on another site. I always run my motor out of gas before I trailer my boat.
 
Just want to say thanks to all for the info. Put the head gasket on and checked compression. Both cylinders are reading 60. Gonna try and fire this thing up when it warms up. Will let you know the results. Thanks.
 
Started motor today and it started fine,no white smoke, idles down ok?,but it doesn't want to go to fast speed. The motor vibrates and sputters and won't get to a fast idle? I know you're not supposed to run them at full speed in a barrell, but I can't get it to a fast speed?
 
Could be running on one cylinder !!--------Do you have spark that will jump a gap of 1/4" or more on both leads ??------------could be a problem in the lower unit.--------The lower half of the driveshaft is a " shock absorber " unit.-----The spring in it is know to break and jam the lower unit up.
 
Hey racerone just took plugs out and grounded to motor and pulled starter rope and got good bluish spark on both plugs.Dk about jumping a 1/4" because I didn't have a way to check that. When I ran motor in tank it shifted in forward and reverse. The shifter handle has a little play in it. Could plug wires be crossed? I put them back the way they were when I bought this motor? would it start if the wires were crossed? Thanks
 
Of course it will not start if wires are reversed , no way will it run !!!!-----Check to see if the spark will jump a gap of 1/4 " that is not that hard to do and mast important !!!!--------If you do not want to or do not understand the importance of checking spark , that is OK too.
 
Thanks, I didn't think that it would start,but just wanted to make sure. I know a car will run if a few wires are reversed,but we are talking four cylinders or eight compared to two. I'm not STUPID I build Camrys for a living. I just wasn't sure how to check gap for a 1/4". Is there a certain tool or a certain method you use for checking the gap?
 
What color of spark is a good spark? Blue? and is orange a weak spark? Hey racerone had an old plug and bent the tab to about 1/4" gap. Would that be a sufficient way to check the spark gap?
 
Hey Racerone thanks for all your help. Went and bought a spark tester today(the wife didn't want to hold the plug anymore with pliers) My number two plug wire was firing intermittently. When it did fire it would be blue a jump 1/4" gap. So I'm thinking loose at the coil or a bad coil. Again thanks for your advice and answers.
 
Hey to everyone. Just changed a coil and got this motor running good. Then I put the clamshell hood on it and it was still running good. Then I shut it off. Came back to start it later and it wouldn't rev up? If I raised one side of the hood then it would run fine. What gives? Also there was alot of smoke. But I am running it in a barrell. Thanks
 
You can't run any outboard in a barrel with the hood on..... causes the carburetor to draw in its own exhaust fumes.
 
Thank you so much for your information. Will try and take it to the creek this weekend and get it out in the open air.
 
Hey Joe just took the motor today and ran it. It runs great. Thanks for all of your advice. I learned alot on this motor. Now I might tackle another one.Thanks
 
Back
Top