Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this OK.

[rodbolt]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

we were all amuatures once. with the proper instruction,training and equipment its not difficult. the 9 measurements I usually do are three at the top,3 at the middle and 3 at the bottom. with a dial bore gauge it takes minutes per hole. some motors the ports will only allow me 2 good measurements in the middle.<br /> I dont bore them anymore sometimes I play with a friends equipment. but I still know what the drill is and what has to be done. its not rocket science it just takes patience, the ability to read the literature and practice. we wont get into running scap on a CNC lathe . I programmed and set up CNC lathes and mills for an explosive plant that made oil field perforating and logging tools for about 6 years, got to run the heat treat and draw ovens as well for a few years. jpoined tha navy and became an FC and did the CIWS primary NEC and was working on a harpoon secondary NEC. got some arthritic like problems and they retired me so now I am back to playing with boats. this time since about 91.<br /> going back to your honing, are you just trying to break a glaze or actually modify the bore size? like hone out scratches.

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

You definitely have the credentials.<br />No, I'm just trying to remove some scratches and install a new piston the compression was down to 90 PSI. It's a 1973 or 74 vintage MERC500 so I'm not that worried if I make a mistake. <br /><br />Alex

 

[Clams Canino]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

If you're an amateur and you're just trying to deglaze a hole, I reccommend the ball type "dingleberry" hone and new rings all around.<br />It's easy to make a "catastrophic" mistake with a rigid hone, where if you use well oiled balls and stay under 1/2 minute in each hole, you can't really make anything any worse.<br /><br />On an outboard of *that* age and value, scratches that are not above the ports don't really count for much, and little scratches (not gouges) that are above the ports will still get "some" relief.<br /><br />If it needs more professional boring or honing, take it to a machine shop. Unless you plan to do this a lot, and you really want to learn the skillset.<br /><br />-W

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Should I hone all the holes or just the one that is affected? This dingleberry hone generates a cross hatch pattern?<br />Thanks<br /><br />Alex

 

[Clams Canino]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

All of them.... and re-ring all of them too.<br /><br />It will generate a cross hatch if you "pump" it up and down while it spins. Use a reversable drill at about 1/2 speed and go both directions, pumping the drill top to bottom as you go.<br /><br />-W

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

As you are going down the cylinder from top pumping up and down in short strokes till you reach the bottom? Should the speed of the drill be such that you can visibly see and follow the rotation of the hone around the cylinder?<br /><br />piston dia above rings 2.551<br />cyl block finish hone 2.565<br />bore 2-9/16 0r 65 mm. The specs listed are from the MERC manual.<br />The first spec is self explanatory but the next two could stand some interpretation.<br />Thanks <br /><br />Alex

 

[Clams Canino]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Yes, and speed perhaps a bit faster than visible but not wide open drill. But remember that "above the rings" is from the perspective of the moving piston. therefore that area is near "the bottom of the hole" when checking it out.<br /><br />-W

 

[rodbolt]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

ya need to keep reading, the skirt diameter is more critical than dia above the rings. max taper or out of round from finnish hone dia is .003"-.004" and the skirt dia for std is 2.872 for a mid 70's early 80s inline 6 and the finnish bore std is 2.875, that means piston to wall clearence is .002".<br /> tha above numbers on a piston are examples out of the merc manual #90-86134---3. if you attempt to hone out any scrathes deep enough to leave copper on when a penny is rubbed acrossed the scratch odds are you went oversize.<br /> if ya use a ball hone, not reccomended, be aware that only a few strokes are nessasary to break the glaze, if you use a ball hone to remove scars odds are you trashed the chamfer at the port area.<br /> I have seen it happen many a time on all makes of blocks. will create a ring problem down the road if the port area is deformed.

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

You guys definitely know your stuff, but there will be differences of opinion even among experts.<br />What does Rodbolt recommend using in order to achieve the desired effect?<br />Thanks<br /><br />Alex

 

[Clams Canino]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

I think he reccomends taking it to a machine shop or someone experienced in the use of a rigid hone or to re-bore the cylinder. <br /><br />He's right that skirt diamater of the piston is critical to avoid "piston slap". I was refering to the relative impact of vertical scratches, a scratch above the ports is worse for compression than one below the ports.<br /><br />And he's right that trying to use a ball hone to actually remove scratches and scars will not be a "good thing". However, if the cylinder just needs de-glazing and you keep it under 30 seconds to a hole (15 each way) I think he'll agree you can't do any harm.<br /><br />Lastly it comes down to what you want to get out of it. Kinda the difference between a "repair" and a real overhaul. You get out what you put in.<br /><br />-W

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Like I said you guys know your field and I really appreciate the input. Theoretically speaking just putting in new rings would make a huge difference?<br /><br />Alex

 

[Clams Canino]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

A positive difference is the best statement. <br /><br />But you *do* have to deglage or the new rings can't seat on the old "mirror" finish.<br /><br />-W

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Can you explain in more detail the fact that the rings can't seat on an "old mirror" finish.<br /><br />Alex

 

[rodbolt]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

I will agree with clams.<br /> if your not trying to get the scratches off and use a medium/fine grit stone and do what your gonna do for 30 sec or so at 1400-1800 RPM or less a ball hone will adequately deglaze the cyl walls. one of the first signs of collapsed piston skirts or excessive skirt to wall clearence is hard starting and poor idle when all else checks ok. the piston must seal as well on the down stroke as the up stroke to insure adequate primary compression for fuel/air transfer and to prevent incoming air/fuel contamination.

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

I still want to know why a ring won't seat on an "old mirror" finish. <br />Thanks<br /><br />Alex

 

[rodbolt]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

cause its to slick and the new rings wont wear into the hard glaze.

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

So, in order to do a deglaze(minimum) I have to spray copious amounts of lubricating material, concentrate on the up and down movement of the grinder, and watch the clock. Did anybody say I should reverse the drill in order to get a better effect? If no, I then proceed to make my measurements for adherence to specs.<br />Is that about it?<br />Thanks<br />Alex

 

[Clams Canino]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

If your pre-existing measurements meet specs, THEN, a quick deglaze with a 3" ball-hone won't hurt you at all. You need to reverse the drill to get a "cross-hatch" effect.<br /><br />New rings can't seat without it.<br /><br />-W

 

[crem1]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Do you enter the cylinder with the drill rotating or stationary? So really I can do one cycle(in and out) with the drill in the forward position, stop, and one cycle with the drill in reverse? <br /><br />Alex

 

[rodbolt]

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this

I never saw a reversing hone. usually it will wipe the stones. the cross hatch is controled strictly by the strokes per minute of the hone. <br /> but without a claen crosshatched surface its difficult for rings to seal. the cross hatch also retains oil for lubricating the moving parts.\