Mercruiser Inliner Swap Progress...165 Rebuilt I6 replacing the old 470

mickyryan

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man that's piston slap how long have you had it running at operating temp to see if noise went away? I mean if it isn't that id be shocked. because most likely loose fitting piston will go away after heated up to some point . unless its a really bad fit or a cracked skirt but you can hear a cracked skirt at idle .
 
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WOEISMEIGOTTA470

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I'm not convinced just yet that it's a rotating assembly issue Micky. Going to try and plot my advance curve. Then open up my carburetor and see what size jets are in there.
Here's a video that I found of the exact symptom I'm hearing. Again, engine runs and sounds great in neutral. Noise only happens under heavy load, hard acceleration.
https://www.youtube.com/watch?v=nxuBmB6TTrc
I haven't had time yet to fool with it more, also it's been really cold out lately. Going to try and work on it later in the week. Thanks.
 

proshadetree

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That sounded like spark knock to me. But not being there in person makes it more difficult to tell. Most of the time richer mixture or less timing will cure it. Did you have a plug reading off this engine? Light color with specks indicates lean mix.
 

WOEISMEIGOTTA470

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That sounded like spark knock to me. But not being there in person makes it more difficult to tell. Most of the time richer mixture or less timing will cure it. Did you have a plug reading off this engine? Light color with specks indicates lean mix.

Hi proshadetree,
Yeah I got a pretty good read I think, posted a good pic on post #218

http://forums.iboats.com/forum/boat...replacing-the-old-470?p=10315577#post10315577

I installed fresh plugs on a warm engine, started it up and immediately ramped it up onto plane for about a min ran it at about 3500rpm then immediately shut the engine off to read plugs.
 
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proshadetree

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Well they certainly look good. Have you checked one after that? Have you tried slowing the initial timing down some?
 

WOEISMEIGOTTA470

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Well, despite the weather being less than ideal this weekend (freezing temps... snow Saturday), I managed to record the ignition curve of my distributor and compare it to the two ideal timing curves for this engine that I found on the web. I made two passes, ramping up slowly to certain engine speeds, holding it steady and noting down the amount of advance. Between 1st and 2nd tests, I re-adjusted distributor's initial timing of 5deg. BTDC hence a slight difference in the curves, but results are pretty much the same.

165_Ign_Timing_Curve_Test_zpsbtljv1nu.jpg


As you can see I'm pretty darn close to the "prestolite" curve (green), after 1500RPM it starts to accelerate a bit more rapidly towards total advance of around 26-27deg. adjusted.
What is a bit confusing is the two ideal timing curves specified from Merc (red & green) for this engine are quite different. The red curve doesn't achieve total timing until ~2800RPM, while the green curve achieves total timing closer to the 2K mark. The path to total timing on the red curve is more gradual as well, the largest gap is about an 8deg. difference @ the 2K mark. How much this actually makes a difference? I don't really know but it might be significant.

Here is another look, this time I compared Test #2 data VS. the minimum and maximum limit curves for each type of distributor:

Merc_165_Ign_MinMax_zpssgtagagh.jpg


As you can see if I were to have the prestolite distributor, I'm right in the ballpark and would certainly give it a pass. Only thing is I'm almost certain that I have a Delco Remy. But should it even matter? It's interesting how the curves are quite different and has me wondering why? Even with all this data I'm not 100% convinced that these curves are right for my engine anyways.
For example if you look at this link for where I got the "prestolite" curve (http://www.boatfix.com/merc/bullet/95/95_11.PDF)
You will see pages 1-6 are all for the 3.0L inline 4 with varying ignition setups. Just look at how different each of those curves are!! I mean pages 3,4,&5 show the total advance coming in wayyyy later at 4K RPM. So I guess I'm having a hard time understanding why there is such a difference when engine displacement is the same???

Maybe the answer is in different ignition setups you might have "hotter" spark with these new digital setups vs. an older points based system. Maybe that has an effect on what the curve should look like? Another possibility I can think of is that the advance curves for the merc 165 is outdated and based on leaded fuels which were more resistant to pre-ignition?

To me, I still say that my advance is coming in wayyy too quick for my application, to have total timing come all in at what is effectively a fast idle of only 2-2500RPM does not make any sense to me. The boat hasn't even had the slightest chance to plane at those engine speeds. My next course of action is still to pop open the carb just to make absolutely sure the correct jets are in there. Then I'll try throwing some stiffer springs in the dizzy and try to get a less aggressive curve.

One more thing - thanks for putting up with my crazy...lol it never seems to end.
 

mickyryan

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ok so after 3k does the knocking stop? if not id say there is your answer it isn't the ignition.
 

proshadetree

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Do not compair 4 cylinder timing curves to 6 reguardless of displacement, they are diffrent critters. The 6 cylinder engines max rpm is around 4 grand in marine application the 4 cylinder is up to 4800. As far as diffrent distribitor curves for diffrent brands thats normal. Max and base timing is what you need to start with. Tweaking the curve might gain loads of performance in a car but it would hardly even be felt in a boat.
 

WOEISMEIGOTTA470

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I undestand that the 3.0L is a different engine and has different characteristics, but I was only pointing out how many varying curves exist for the 3.0L. I still think that the 3.0 actually is similar enough for a comparison. It is effectively the same engine less two cylinders, and engine loading is under the same marine environments.
Micky, the engine has always stayed cool/normal, coolant temps steady at 160. First heard the noise the 1st time I had the boat in the water, and tried planing her off. The noise comes in at around 2800, and after planing, noise diminishes around the 3500 mark but still doesn't sound good. Engine has always been warmed up when hearing the sound.
 

mickyryan

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kk well piston slap would go away unless it was way out of tolerance but a cracked skirt would barely be audable at idle present loud under load and then be again quieter once planed off but never totally going away if you had a ear for it , at least that's exactly how it was on mine.
crossing fingers its just some weird timing thing for you , btw my engine in my truck has piston slap but I will drive it till it blows and most likely it wont be from the slapping piston lol
 

proshadetree

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You can take 2 twin engines same in every way and one will take more timing and less fuel with no issue.The next one will rattel even when set to spec. Hot spot on the head, burr or carbon on a piston, heck many things can cause it. Most of the time more fuel or less timing will stop it.
 

WOEISMEIGOTTA470

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Hey guys! Long time!!! Hope everyone has been thoroughly enjoying their summer! I've been MIA for a while I know so...lot's to catch up about. I have good news and not so great news...
Good news is my summer has been going well and I've been enjoying the heck outta my boat recently. Awesome. Not so great news is the fact that I believe the engine has some sort of internal issue and most likely needs to be taken all apart for further inspection/rebuild. I say this because I've done all I can with playing around with ignition timing and carb tuning. I actually got the thing to run better with smaller sized jets #62, vs the biggest ones I could find #81's. (I found the mercury spec for the 165 are #62 jets Mercury P/N 1397-3827).

I've been working as much as I can on this thing, I was actually living in New Orleans from April to July and was away from working on the boat that whole time which is another reason why I haven't been on the forums at all. My plans now are to just work on getting an engine cover built for it, and try finishing the cockpit interior. Also I really need a freaking ladder for it, can't wait to mount my swim platform cause getting in and out is a real struggle lol. Those are my two top priorities, but am also trying to enjoy as much of what's left of this summer weather (does this make me a cheater?) don't care lol. Anyways, hopefully the engine will last long enough for what nice weather is left, before I tear it down over the fall / winter. Gotta get myself a seatow membership lol.

Like I said I hope everyone is enjoying themselves and look forward to catching up with everyone's projects!
 

WOEISMEIGOTTA470

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Also want to just say how livid I am with photobucket argergegegrggeghhh!!
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burn it downnn

Anyways, Imgur is my new best friend. Here are few recent pics!

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WOEISMEIGOTTA470

Petty Officer 1st Class
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Messages
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Here are some shots of the "firewall" if you will, that I'm building. It's easily bolted in place using 1/8" thick AL angle and 1/4" bolts. Plans are to have a hinged padded section that spans the transom about 12" wide, will make it easier getting in and out of the boat and provide storage. Seat backs will be mounted to this panel.

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WOEISMEIGOTTA470

Petty Officer 1st Class
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Messages
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Here's a quick video of a run I did 2 weeks ago. Engine is freakin' loud!! Really needs a cover to quiet it down some. Turning about 3,300 rpms, likes that speed, anything above 3500 and it rattles, sounds gritty.
 

WOEISMEIGOTTA470

Petty Officer 1st Class
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Aug 31, 2012
Messages
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Here's a quick video of a run I did 2 weeks ago. Engine is freakin' loud!! Really needs a cover to quiet it down some. Turning about 3,300 rpms, likes that speed, anything above 3500 and it rattles, sounds gritty. Anyways enjoying the friggin thing!
 

archbuilder

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Sep 12, 2009
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Looks like you have been getting good use out of her. To bad about the motor, but I am sure you will get it sorted out.
 

WOEISMEIGOTTA470

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Resurrecting this old thread of mine to give a little photo update. I managed to successfully have 4 solid seasons, even if the engine's been a bit on the noisy side. I have good power however, and oil pressure and temps have remained stable. I have added a few more pieces to the boat since my last post.
  1. Fiberglassed and gelcoated interior panels white along with rear seat mounts
  2. Finished wood engine cover with interlux topside paint, and added acoustic foam liner
  3. Modified used teak swim platform, and mounted using custom S.S. uni-strut channel pieces bonded to the hull with 3M 5200.
  4. Added a telescoping swim ladder under platform
  5. Added RGB LED Deck Lighting
  6. Mounted Bimini Top
I may be missing some items, and I still have some things I'd like to finish. She still ain't perfect but hey, in the meantime I've been thoroughly enjoying it, and I gotta say the swim platform is the best feature no doubt!

Hope everyone is well and staying healthy throughout this crazy pandemic. I look forward to catching up on some old threads and some new ones too! Happy 2021!

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