Hone or deglaze?

[redjmp]

Re: Hone or deglaze?

Something went wrong with 3 and 4. Number 5 I think inhaled a piece of number 3s piston ring. I say that cause 1, 3, and 5 share the same exhaust manifold and exhaust tuning does create pressure pulses that flow back into the cylinder. Number 5 is clean compared to 3 and 4.

I agree.
Looks like #3 & #4 were the cause as #5 isn't missing the top rig like 3 & 4 are.

Maybe because #3 & #4 are 3 ring pistons and #5 is a 2 ring?
Hmmmm.....

 

[Jlawsen]

Re: Hone or deglaze?

Something went wrong with 3 and 4. Number 5 I think inhaled a piece of number 3s piston ring. I say that cause 1, 3, and 5 share the same exhaust manifold and exhaust tuning does create pressure pulses that flow back into the cylinder. Number 5 is clean compared to 3 and 4.

One of the problems with trying to figure out what happened is that there's no way to be there to see it.. LOL. We just guess and sometimes we're right. I'd buy your explanation as plausible..

Canoemang - Glad you took that the right way. Sometimes my writing doesn't show the smile on my face when I'm explaining things.

Your next step is to get some muriatic acid and getting all the aluminum out of those cylinders and the exhaust ports. I guarantee there is a lot of slag in the exhaust that you might not see right now. You have to get it out of there.

Once you've scrubbed those cylinder walls I'll bet you have scoring. How deep they are can only be checked with a bore gauge. I can tell you stories about trying to get away with things on these motors but it will suffice to say that you won't.

It's important to realize that the depth of the scoring on a cylinder wall must be doubled when you figure how much you have to take off to correct it and make the cylinder round. If you have a scratch thats .005 deep you have to open up the bore by .010. They don't make oversized rings so you're only choice is to bore it to .015 over or your rings will never seal.

If you attempt to clean up a deep score with a brush hone you will taper the cylinder, there's no way that you can prevent that from happening with that type of hone. If you end up with more than .005 taper that's too much and you'll need to bore it anyway.

 

[canoemang]

Re: Hone or deglaze?

Why does it taper with a brush hone?

and if thats the case why would they sell a product that tapers cylinders?

I understand the rest.

Also.. considering all 6 cylinders look identical but with 1,2 n 6 all sitting at 120 psi..

wouldn't they also have poor comp?

 

[jimmbo]

Re: Hone or deglaze?

I agree.
Looks like #3 & #4 were the cause as #5 isn't missing the top rig like 3 & 4 are.

Maybe because #3 & #4 are 3 ring pistons and #5 is a 2 ring?
Hmmmm.....

#3 is the 2 ring piston. the pic left to right is 5, 4, and 3. 3 and 4 share a carb and therefore a reed block. There is a reed block between the two on the right, so these would have to be 3 and 4. Also the power ports are are the starboard side of the engine.

 

[canoemang]

Re: Hone or deglaze?

Parts come today. I'll be using the diluted acid wash and i'll be honing and reassembly.

As i do see a difference in people using a ball hone or a 3 stone, i'll be using the 3" ball hone, i will also be checking the ports for edges and chamfering if needed. It is hard to get an exact opinion on here when people say different things and it is hard to know who is rite.

As much miking as i have done everything seems to be within spec.

Hoping all goes well..

on a side note: 95 degrees today.. my shop has a fan.. i'll be fine.. rite? lol

 

[Faztbullet]

Re: Hone or deglaze?

As i do see a difference in people using a ball hone or a 3 stone, i'll be using the 3" ball hone,

Make sure it will go all the way to the top of cylinder, most of the time they just wad up and leave the last 1" untouched, use a mirror and light to inspect the wall. A flexhone will remove very,very little material from the cylinder and did you mike the tops of pistons?

It is hard to get an exact opinion on here when people say different things and it is hard to know who is rite.

I just do it one way ,correctly. Been wrenching and racing these for over 35+ years........

 

[canoemang]

Re: Hone or deglaze?

Make sure it will go all the way to the top of cylinder, most of the time they just wad up and leave the last 1" untouched, use a mirror and light to inspect the wall. A flexhone will remove very,very little material from the cylinder and did you mike the tops of pistons?

I did do a thorough job with the hone and i was surprised by the results.. I didnt get carried away but i did follow the directions as for rpm's and for amount of time on the hole.

as for miking the tops..

Above the 1st ring on all 6 (new and old) was miked @ 2.844

The skirt on all 6 (new and old) 2.863 - 2.864, There was variance between new and old pistons alike.

Yup, the cylinder walls might feel smooth because the scoring is filled in with aluminum. You can hit them with a rigid hone or wash them with muriatic acid run a bore gauge down them and then make a decision about boring or honing. If you all want to fill up your stones with aluminum go ahead and skip the muriatic acid. I can't afford it.

That Muriatic acid is some nasty stuff, even adding it to water it was smoking. I bought a gallon at Home D. and did the wash on all 6 cylinders using neoprene gloves and taking care to not drip any. I had no reaction on any cylinders. I used 50/50 mixture because full strength seemed a bit much

So if i am reading this correctly.. lack of reaction on any cylinders and my measurements all the same from new to old pistons with no variance, i dont see any issues.


The power head is assembled and i'll be putting it back on this morning and running comp test,timing and spark prior to break in.

 

[canoemang]

Re: Hone or deglaze?

Assembly complete.

Ran it for 4 hours today at 40:1 while varying RPM

Strong spark on all 6

Timing set at 18 degs.. for now

Compression is as follows:

Cyl 1 @ 120 PSI (hone/new rings)
Cyl 2 @ 120 PSI (hone/new rings)
Cyl 3 @ 115 PSI (hone/new rings/new piston)
Cyl 4 @ 120 PSI (hone/new rings/new piston)
Cyl 5 @ 120 PSI (hone/new rings/new piston)
Cyl 6 @ 120 PSI (hone/new rings)

Rebuilt jet foot/new liner/new impeller/new bearings.

Prior to rebuild was running at 4800 RPM on a cool day

90 degrees today/high humidity and running at 5000 RPM and never hit WOT..

on a side note:the 1984 merc 115 is cracked open and im sure ill have questions..

Thanks for the help.

 

[jimmbo]

Re: Hone or deglaze?

Merccury used to require a breakin mixture of 24:1 for the first 10 hours

 

[canoemang]

Re: Hone or deglaze?

Mercury used to require a break in mixture of 24:1 for the first 10 hours

I can see how with a new engine Mercury would require 25:1 for a break in. What i was told is run one tank (17 gallons) at 40:1, varying RPM and not hold it more than 30 seconds at any RPM.. then run it hard..

17 gallons ran through it as of this morning,WOT = 5100 RPM, which is better than what i was running this spring.