2.5 Mercury build

[bajaunderground]

Re: 2.5 Mercury build

Can't wait to see the numbers on boat? What 26P prop are you running?

 

[wired247]

Re: 2.5 Mercury build

When Jim Ruck had my block a few months ago to prt it to 225 pro max specs, open up the exhaust chest and cut the rod slots he also machined my heads for minimum volume with pump gas . In this case that was 35 cc . He also straightened the bores up which I did verfy with my bore gauge and they were all spot on. With a reputable machne shop this isnt really necessary but its something I do as an old habit. After a cleanup hone my bores measured 3.503" with no taper whatsoever. Thats a bit on the high side but nothing I'm worried about using with stock pistons. My pistons were mostly in spec except for one with some scuffing that changed out. After I got it all together I pressure washed the block and let it dry on the radiator overnight. The pistons and heads I ran through the dishwasher when the wife was at work. I did not bead blast the pistons . Thats a good way to lose embedded glass material in your motor. I soaked them in simple green and spent a good two hours scrubbing the crowns with a green pad to get all the carbon off. The ring grooves I carefully scraped with the usual used ring sharpened to a point. When they were all clean I weight matched the rods and pistons to within a few grams after checking the rod ends for roundness. Mine all looked good. I did have to replace one rod as my replacement piston was too light so I used a heavier rod to get the weights the same. I decided to change all the rod needle bearings while I had it apart although it probably wasnt necessary. I use lubriplate to hold them in place. Lubriplate is thinner than the Mercury spec bearing gel and doesnt work as well to hold the needles on the pin and slide into the rod end as Merc grease but I think its a better lubricant. What this means is that it takes a bit more effort to pack the needles in the rod end. I just grease them up and shove 4 or 5 in at a time. Once they are in place I grease up the washers pretty good to hold them in place and insert them in the piston with the rod/bearing assy and shove the pin in. Then the joy of installing the retainers.

 

[wired247]

Re: 2.5 Mercury build

Can't wait to see the numbers on boat? What 26P prop are you running?

I was going to go with a 26 pitch Merc pro et. I still may do that if and when my bonus check comes in but inthe mean time I picked up a 28 pitch big ear chopper and I sent in it to get reworked to Mercury ET specs. I also have a 25 pitch Merc Laser 2 to run.

 

[wired247]

Re: 2.5 Mercury build

On to loading the pistons in the block. The rings I got from Chris Carson are installed on the piston. I suppose there is a Mercury ring installer I could use but a 3 1/2" worm screw clamp does the same thing. Clamp the rings done lightly with the against the pins and push the pistons into the bores.

Heres all the rods in the block. I installed new torque to yield bolts . They get torqued to 32 ft lbs and then get cranked another 90 degrees. Feels like about 100 ft lbs and it stretches the bolt to the point where it won't stretch any more. Loctite is never needed on a properly torqued bolt and all I use is oil. Never torque a bolt dry.

Heres the crank installed. I reused the main bearings as they were just changed last year and the crank is perfect. I did manage to snap a crank ring when I plopped it down but luckily I had a spare and installed it in place. Note the metal cage rod bearings which are one of those things you need if you want to go much above 6000 RPM. Mercury rods of this vintage are cracked cap and are forged in one piece and then fractured . It is very important to make sure the rod caps are lined up properly and are fairly simple to do by running your fingernail over the outside of the cap where the cap and rod come together. You will feel if they are even slightly misaligned.

 

[wired247]

Re: 2.5 Mercury build

I use that thin permatex to seal the front half. Sealant, cork and then sealant. Lay the top down and slide the end caps in place with their bearings and bolt the mains down.

Note the dual regulators. I am running a 16 amp stator and flywheel so I will only be using one of the regulators but I will keep the other one there to take up space and to use as a spare.

 

[wired247]

Re: 2.5 Mercury build

I am using an oil injector blockoff from Mercury and will be running 40:1 premix. Plops right into the oil injector drive hole and takes up the space in the block.

Heads go on . Grease on the bolt holes and oil on the threads. Torque to 35 lbs.

 

[wired247]

Re: 2.5 Mercury build

I used Chris Carson fiberglass reeds in place of the original steel reeds on the 4 petal rubberized cages from the 2.0/150. These are good high velocity cages for under 7000 RPM use. If I were going faster I'd use 7 petal teardrop cages or better yet the 5 petal rubberized 240 jet cages ( if I could find them ) .

 

[wired247]

Re: 2.5 Mercury build

By this point I have the manifold bolted on and the bearing caps are torqued down. I screwed the studs on and picked up the long block and dropped it onto the assembled mid section. I removed the engine electrical system intact aslong witht he trigger so I was able to slap it all together without thinking about it too much. I installed new bleed lines and replaced the three bleed check valves I broke or were broken for me during the machining. After the trigger was reinstalled along with the stator I installed the flywheel , spark plugs and rejetted carbs. All the electrical, linkage and flywheel and the the external stuff came from the same motor so I knew if I turned the key today it would fire right up and of course it did and idled right where it was supposed to. Sounded good and throaty without the mid section liner. I still am going to go through and time everything this weekend along with a carb sync etc before I give it a good long break in. I'll walk you through the whole process when I'm done.

 

[Faztbullet]

Re: 2.5 Mercury build

I installed new torque to yield bolts . They get torqued to 32 ft lbs and then get cranked another 90 degrees.

My $.02 is you should always use a torque angle tool to add the additional degrees to rod and head bolts. Never reuse a bolt that has had additional degrees added to it such as rod and head bolts. The reason being torque to yield fasteners are stretched to the point that they are just about to "yield" or lose their springiness.

 

[canoemang]

Re: 2.5 Mercury build

Nope.

Im surprised.. Lot of guys over there have gone through this once or twice im sure..

Not saying this isnt a good place for it.. just saying its what they specialize in..

 

[wired247]

Re: 2.5 Mercury build

My $.02 is you should always use a torque angle tool to add the additional degrees to rod and head bolts. Never reuse a bolt that has had additional degrees added to it such as rod and head bolts. The reason being torque to yield fasteners are stretched to the point that they are just about to "yield" or lose their springiness.

Torque to yield bolts are one time use items. I know its hard to wrap your head around torquing that tiny rod bolt to what must be 100 ft lbs by the time the 90 degree specified angle is drawn in but that bolt is made to do it....once. After that it's trash.

 

[wired247]

Re: 2.5 Mercury build

Im surprised.. Lot of guys over there have gone through this once or twice im sure..

Not saying this isnt a good place for it.. just saying its what they specialize in..

This wasnt done for me. Ive built more engines than I can remember. I documented this for you guys and especially for the guys who have always wanted to do this sort of thing but thought it was over their head. Its not. Its pretty damned easy actually. The S&F guys live this stuff already.

 

[Dukedog]

Re: 2.5 Mercury build

"Then the joy of installing the retainers."

This is why I couldn't live without tha Merc wrist pin tool outta all of 'em..............

 

[wired247]

Re: 2.5 Mercury build

I still have holes in my fingers. Ive found I can work them in pretty good with a pair of needle nose pliers and a screwdriver but its still a pain. If I did this more than once or twice a year I'd invest in the installer.

Why aftermarket pistons don't come with something less cheesy than those clip retainers is beyond me. Even double spirolocks or C clips would be better.

 

[1FASTLASER]

Re: 2.5 Mercury build

This has been an awesome thread so far

 

[wired247]

Re: 2.5 Mercury build

Took her out this morning for a quick 4 mile spin. 28 degrees outside and I am technically at work. Ran 71 MPH GPS against the current at 6100. Still lots of setup work to do but it looks promising.