Yammerhead
Cadet
- Joined
- Mar 29, 2008
- Messages
- 15
I have to decide what I want to do for the outboard on my boat. I'm new to boating so am looking for input.
I have two motors I can go with for my 1975 16' fiberglass tri-hull. The motor currently on it is a 1975 Evinrude 85HP that has been on this boat since day one. It has power tilt, but not trim. It has had the power pack replaced a couple of times in it's lifetime and the shaft welded some time ago. (I bought it from it's original owner) I had to get some help from this forum to get it running, but now it seems to run and shift pretty good. I checked the compression with a cheapo compression tester and each cylinder read between 106 to 110 PSI.
Choice number two is a 1973 Mercury 85HP that I have taken off another boat. It has power tilt and trim. I tested it last week and it fired up instantly and shifted good as well. I don't know the specific history of this motor, but the guy I bought it from thought it may have had work done to the gears at one time. On the same compression tester, each cylinder on this motor tested between 134 and 139 PSI. To put this motor on the boat will be a bit of a PITA. I'll have to re-drill the transom for the different bolt pattern, re-mount all the controls, etc.
Do these two motors have much different compression ratios? Should I expect to see that big of a difference in compression or is that an indication that the Evinrude is that much more worn out? What is the reputation of these two motors? Is one historically more problematic than the other?
Thoughts anyone????
I have two motors I can go with for my 1975 16' fiberglass tri-hull. The motor currently on it is a 1975 Evinrude 85HP that has been on this boat since day one. It has power tilt, but not trim. It has had the power pack replaced a couple of times in it's lifetime and the shaft welded some time ago. (I bought it from it's original owner) I had to get some help from this forum to get it running, but now it seems to run and shift pretty good. I checked the compression with a cheapo compression tester and each cylinder read between 106 to 110 PSI.
Choice number two is a 1973 Mercury 85HP that I have taken off another boat. It has power tilt and trim. I tested it last week and it fired up instantly and shifted good as well. I don't know the specific history of this motor, but the guy I bought it from thought it may have had work done to the gears at one time. On the same compression tester, each cylinder on this motor tested between 134 and 139 PSI. To put this motor on the boat will be a bit of a PITA. I'll have to re-drill the transom for the different bolt pattern, re-mount all the controls, etc.
Do these two motors have much different compression ratios? Should I expect to see that big of a difference in compression or is that an indication that the Evinrude is that much more worn out? What is the reputation of these two motors? Is one historically more problematic than the other?
Thoughts anyone????
