1978 Mercury 80HP rebuild Spec ??

[Zrt1200]

Re: 1978 Mercury 80HP rebuild Spec ??

My local marina wanted $300. to bore the 4 cylinders, I bored the cylinders my self at work on a CNC boring mill. The cost was 2 hours of pay and 12 pack of beer for the boss!! The cost of new pistons was $425. I went with the wiseco pistons because of the KD style of rings.

 

[Faztbullet]

Re: 1978 Mercury 80HP rebuild Spec ??

I am going to assume you went .020 over as Wiseco doesnt make a .015. Make sure that your finished bore size is 2.895 +.001 so it dont have a chance to cold sieze. Finished bore size is measured after crosshatching.

 

[Zrt1200]

Re: 1978 Mercury 80HP rebuild Spec ??

That is correct. I went .020 over with the wiseco's and the finished cross hatch is 2.896. I still have to check the other two rods as I have just been busy with work and other things.

 

[Faztbullet]

Re: 1978 Mercury 80HP rebuild Spec ??

When I bore a block that uses a Wiseco piston I will set my micrometer on boring bar 1/2 thousand over on finishing cut. I will bore it .010 over first pass,.0055 on finishing cut, after honing bore would be 2.8957 to 2.8959. I do this because forged pistons expand 2 times faster than the steel liners, and that engine doesnt have a t-stat to control temp. That is why Wiseco says to let engine idle before WOT use.

 

[Zrt1200]

Re: 1978 Mercury 80HP rebuild Spec ??

I did not realize wiseco recommends to let the engine warm up before WOT. That's ok with me though as I always let my motor warm up before pulling away from the dock.

 

[Faztbullet]

Re: 1978 Mercury 80HP rebuild Spec ??

Yep, it in the box with piston ,the little blue install/spec sheet.

 

[Zrt1200]

Re: 1978 Mercury 80HP rebuild Spec ??

Sorry guys as I have not been working on this motor for a while. They are killing us at work for the last couple of months. I mean 12+ hours a day, 6 days a week. On my day off all I want to do is sleep in my LazyBoy. I will be back it after the 1st.

 

[Zrt1200]

Re: 1978 Mercury 80HP rebuild Spec ??

Well, There still killing me at work but this past week has gotten a bug in me again as it is turning nicer outside. I will be updating shortly. I am glad winter is over but it sure has not felt like it as the last couple of mornings here have been 30 and 32 degree's!!