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Bad vibration/knock underway

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Topic: Bad vibration/knock underway
    Posted: March-23-2019 at 10:46am
Hey guys, haven't been in here in a while, back with problems unfortunately.

Boat: 1989 Ski Nautique, PCM LH 351, 1.23:1 trans, acme 470 prop. Owned since 2010, and has been a great running boat for years.

Last year this engine developed a bad oil leak from the rear intake China wall seal, so naturally I decided to replace that. Other than oil leak, boat was running fine in October when it came out of the water. Manifold was replaced with new gaskets, and I added a DUI distributor as well to replace my worn out stock unit. Anyway, it seems to run great on the trailer, idle is good, throttle response is snappy, so I thought all was well. On the water yesterday there is a horrible vibration starting just off idle and getting worse as rpms come up, eventually sounding like a full on knock, almost sounds like something is smacking the hull. The engine pitches fore and aft up til around 1500 rpm and then settles down, but the vibration just gets worse and louder. It is not subtle.

Things that have been checked this far:

Firing order: ohmed out plug wires and verified everything is correct. Firing order on tag is 13726548, CCW around the distributor, cylinder 1 is left bank closest to the front, cylinder 5 is right bank front. I actually even tried the other 302 firing order as a troubleshooting step just in case someone put a 302 cam in it before I bought it.

Distributor clocking: rotor points at #1 plug wire at TDC on compression stroke of #1. Compression stroke verified by finger in the plug hole and turning over with a wrench on the crank pulley. Timing set with a light at idle at 10deg btdc and advances smoothly as revs come up.

Compression test: solid readings of 150-170 on all cylinders. More variation than spec, but not bad enough to cause alarm.

Prop appears to be just as clean and nice as when I installed it years ago, lapped to shaft, still tight on the taper. It was smooth in October on the last run of the year and has been on the trailer in a heated garage since, so I don't think anything happened to it or the propshaft. Shaft is a 5 year old ARE double taper.

Plugs: Autolite 24 platniums gapped at .050, brand new with distributor install. Wires are new Taylor spiral pros. Plugs are dark black with sooty residue, not sure if running excessively rich, or a sign of too much idleing on the trailer. Plugs have about 1hr of trailer run time and 15min on water time.

Oil: hasn't been changed yet since manifold install, but is clean with no signs of water in oil. 20w50 VR1.

Oil pressure on the gauge is 50-60psi, same place it has been for as long as I've owned the boat. Temp runs about 160, no signs of overheating.

The vibration is excessive, and the knocking sound is loud, but does not appear to be coming from the motor. My first thought was we had picked up something on the prop that was hitting the hull at speed. No signs on the hull of any contact, and it would be obvious, cause the bottom of the hull is embarrassingly filthy.

Anyway, thoughts on something new to check? I'm stumped. Boat seems to run excellent on the trailer with no load. Thanks!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 10:58am
Is the damper plate original?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote TRBenj Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 11:01am
You’re saying all the right things but I would look at the firing order again.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 11:56am
Originally posted by 1989SN2001 1989SN2001 wrote:

cylinder 1 is left bank closest to the front, cylinder 5 is right bank front.


Keeping in mind that the only silly question is the one that doesn't get asked................

Is your left bank on the drivers side of the boat?

Did you get rid of the ballast resistor when you wired up the new distributor?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 12:18pm
Damper plate is likely original. Will they make the whole boat shake and knock like this? It is very violent.

I'll put a set of fresh eyes on the plug wires again today and verify the order again. Yes, cylinder one is towards the driver side on the front.

Yes, ballast resistor is gone, I put a relay on a 10ga wire to the dissy, straight from the main engine breaker, good full voltage to the dissy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote phatsat67 Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 12:21pm
I’m with Ken. By all accounts your #1 cylinder should be on the RH bank when viewed from the rear of the engine. Which would be the drivers side bank.

Chevy and Mopar puts cylinder 1 on the LH front.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 12:30pm
Now that I'm thinking about the DUI power wire, is it possible that the relay is clicking on and off causing it to miss and run like crap? Maybe I should jumper the relay out of the equation for a brief run, just to rule it out. And yes, cyl 1 is closest to the driver, also stamped 1 on the intake manifold casting.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jonny Quest Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 12:33pm
Originally posted by 1989SN2001 1989SN2001 wrote:


Firing order: ohmed out plug wires and verified everything is correct. Firing order on tag is 13726548, CCW around the distributor, cylinder 1 is left bank closest to the front, cylinder 5 is right bank front. I actually even tried the other 302 firing order as a troubleshooting step just in case someone put a 302 cam in it before I bought it.

Distributor clocking: rotor points at #1 plug wire at TDC on compression stroke of #1. Compression stroke verified by finger in the plug hole and turning over with a wrench on the crank pulley. Timing set with a light at idle at 10 deg btdc and advances smoothly as revs come up.


Based on your description, your firing order and timing may be off. On a small-block Ford, the number 1 cylinder would be closest to the driver's seat. Per your description above, you used the "left bank" or closest to the observer's seat. You may want to re-check your work...

Front of Engine
5     1
6     2
7     3
8     4

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 1:40pm
Usually when your damper goes, it gets really noisy (metallic grating noises) and the boat quits moving as the springs come apart.

Key words would be "metallic grating noises"

It can make noises in neutral too since the engine is turning and the damper plate is turning but the female splines on the damper(which are engaged with the male splines on the transmission) aren't turning or are slipping due to the broken springs.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 2:00pm
So it idles fine, in and out of the water with no vibration or noise - or that's what I was reading - but only has the banging, knocking and vibration while in gear and under load. Is that correct?    If so, you say it IDLES fine .... what about out of gear in the water or on the trailer and raising the rpm to between 1500 and 2500.   Seems like you were indicating there wouldn't be any vibration or noise then either? This to me would help clarify whether the transmission/ drive train may come into play or if it is an engine only problem.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 2:53pm
Yes, when not in gear, it runs fine. Idles great, revs to 3500 no problems, haven't pushed it faster than that in neutral. Timing advances normally up to 30-35ish degrees total at 3000.

Just to make sure everyone is on the same page, cylinder 1 is front of motor, by driver's seat. Opposite side of fuel pump. Number 5 is on front on fuel pump side.

This really feels like an ignition issue, but it doesn't make complete sense. Firing order is 100% right. I even swapped 3 and 5, 4 and 7, to try to early 302 firing order, and that resulted in lots of backfiring and wouldn't idle, so I am confident that I have the correct 351w order.   I even traced the old wires back to verify firing order on the old dissy before I pulled it out. Wires are brand new Taylor, don't hear any arcing around them. Cap and rotor seem ok. I think I will pull all my plugs and check spark at the gap next, just to rule out bad plugs.

Plugs are very black and sooty, could a stuck choke, blown powervalve, or something else in the carb cause it to run rich enough to miss this badly?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 3:23pm
I read the notes above, did you remove the intake manifold to fix the leak before you put it away running great in October or was the repair done after October?
Was the DUI installed prior to October or after.
If the new parts were installed before October and it was running great that would point to the damper.   If not you have good advice above about the firing order.
With a V-8 engines the head mounted the most forward will be #1.
As you look down on the front of the engines you will see the heads are offset, one is forward about 3/4 of an inch towards the front of the engine. #1 is the most forward mounted head and the most forward cylinder.
When a Manufacturer refers to left bank or right bank they are describing the view from the flywheel looking forward, not from the front of the engine looking back.
You can always pop off the distributor cap and touch the key to make sure you have the correct rotation for your plug wires. CW or CCW
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 3:36pm
All parts and repairs were made this past couple of weeks. It ran great but was leaking oil badly in October.

It seems to be starting to run worse on the trailer now, and the exhaust smells really strongly of fuel. How rich would something have to be to stop firing on multiple cylinders under load?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 4:14pm
If your spark/firing order is wrong you are pumping raw gas out the exhaust.
Verify #1 is correct, Verify rotation of the distributor is correct, make sure you have the correct firing order to all 8 plugs and it will start and purr again.

Since you run the 1.23:1 transmission you have standard fire order.
The engine is stock so you want the 351W sequence not the 302.
Good Luck.

NOTE:   forgot to mention, you can have all correct and be 180 degrees out.
#1 comes around Twice on the crankshaft to 1 full turn on the distributor.
To test this you can move your wires 180 degrees on the cap and start the engine.
If this is the problem you can lift the distributor up, rotate it and drop it back down in the correct spot.
You want #1 on the compression stroke not on the exhaust stroke.

Many people have this problem when installing a new distributor.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 4:25pm
Originally posted by 1989SN2001 1989SN2001 wrote:



Plugs are very black and sooty, could a stuck choke, blown powervalve, or something else in the carb cause it to run rich enough to miss this badly?



It seems like you did your homework before the install

Most likely with any of these things you listed (stuck choke, blown power valve), it'll idle like crap.

Have you looked down the throats on the carburetor while it's running?

A new set of plugs would be helpful about now since they're not gonna get any better and will probably get worse unless you get the problem figured out.

A simple thing would be to disconnect the tach wire and see if there's any change.

And bypass your relay like you mentioned.

It's a new distributor, and the problem came about after the manifold and distributor install You wouldn't be the first guy to get a bad one.

If you're baffled, undo what you did and put the old distributor back in and see how it runs to eliminate that variable.or go to your favorite parts store and get a GM 4 pin HEI module and replace the one in the new distributor with that. They're pretty cheap and easy to swap Or a coil too for a GM HEI distributor. They'll be good spares if they're not the problem.

And don't worry about the rotor rotation Mr McD mentioned, if it was wrong the thing wouldn't run at all and that would be a good thing because the oil pump would be turning the wrong way and you'd have no flow or pressure   



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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 4:28pm
Originally posted by MrMcD MrMcD wrote:

If your spark/firing order is wrong you are pumping raw gas out the exhaust.
Verify #1 is correct, Verify rotation of the distributor is correct, make sure you have the correct firing order to all 8 plugs and it will start and purr again.

Since you run the 1.23:1 transmission you have standard fire order.
The engine is stock so you want the 351W sequence not the 302.
Good Luck.

NOTE:   forgot to mention, you can have all correct and be 180 degrees out.
#1 comes around Twice on the crankshaft to 1 full turn on the distributor.
To test this you can move your wires 180 degrees on the cap and start the engine.
If this is the problem you can lift the distributor up, rotate it and drop it back down in the correct spot.
You want #1 on the compression stroke not on the exhaust stroke.

Many people have this problem when installing a new distributor.


It ain't 180 out, it runs, just not very good

He seems to have already checked all the stuff you mentioned
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 7:00pm
Agree with Ken, didn't catch that all the repairs & new distributor had been installed very recently. That would be my first step at this stage - reinstall the old one, complete with the old cap & rotor to see if this problem still exists. I have bought more than a couple parts for various cars, boats, etc. and had them come out of the box defective. Seems like I remember a thread several months ago (or so) where a guy did get a bad distributor and went through heck trying to figure it out. Eliminating the cap & rotor one at a time is a good idea as well, new or not.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 8:40pm
Update:

A neighbor who has been involved with drag boat racing for 40 years came by and immediately noted that it smelled very rich. Pulling the pcv hose off the carb makes a huge difference in rpm, like 1000-1200 rpm faster with it removed, also pointing to being rich. He then ran both idle screws on the metering block all the way in to theoretically cut off fuel from the idle circuit. Supposedly this should shut fuel off enough to stall the engine, but it kept chugging away. He said this is an indicator of a popped power valve diaphragm. The super sooty black plugs have me inclined to agree.

Plan is to pull the primary bowl and change the PV tomorrow, fresh Autolite 24s, and try again.

As another piece of the puzzle, I put a timing light back on it today, and now I am getting intermittent flashes on 4 or five plug wires. I have heard conflicting opinions on whether or not a badly fouled plug that is not sparking will trigger an induction style timing light. Earlier this week, when the plugs were brand new, it had very solid flashing from the light. Now it seems to only be flashing 25-50% of the time on several cylinders. Will also grab a new GM HEI module at the parts store tomorrow, just in case.

Thanks again for the help and ideas today. I will keep the forum updated as things change.

-TJ
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SNobsessed Quote  Post ReplyReply Direct Link To This Post Posted: March-23-2019 at 11:18pm
You might want to refresh the carb while you have it off. Could be dirt in the needle valve too.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: March-31-2019 at 12:41pm
Well I have gone through and fixed a number of problems and the engine is now running excellent. All new gaskets in the carb, and new base gaskets and it is running excellent. Motor stalls instantly when I pull the pcv hose off now, and I can actually get changes with the mixture screws. It seemed to want a little more timing, base set at 12-13 degrees, all in is about 36 at 3000rpm. Idling clean at 750, best throttle response it's ever had. I definitely had some internal fuel leak in the carb, o rings on the accelerator pump transfer pipe we're shot, and I think it was pulling fuel there, similarly to how a bad power valve would act. I also had an air leak between the spacer and manifold. Multiple issues were masking each other and making diagnosis extremely difficult.

However, I am still getting a lot of vibration from the propshaft on the water as soon as the rpms hit 1500 ish.   I put it in gear on the trailer with a friend spraying the Cutlass bearing, and I get the same very heavy vibration, it felt like it was going to jump off the trailer! I have disconnected the coupling from the transmission, and the vibration is gone. However, in a very crude check, it appears to be badly out of alignment at the coupling. With the flange touching on the bottom side, I have about a .040-.050" gap on the topside. The gap stays at the top when I turn the shaft, so the shaft seems straight, just not properly in line with the transmission. I also noticed that the front motor mount studs are leaning forward, as if the rubber in them is degrading and collapsing, causing the motor to pitch forward and thus the misalignment. I aligned this boat to within .003" 4 or 5 years ago, so something has changed.

Anyway, I am assuming this bad of a misalignment is basically trying to put a curve on the propshaft which would make it whip and vibrate like hell as the revs come up. Hopefully adjusting it will make the issue go away, but I do think the mounts need addressing to.

Has anyone here replaced motor mounts with the engine in the boat? I have an engine hoist to support it with.

Do I need to buy full mounts, or will the rubber isolators that DIM sells work for me? Do I need a huge press to install the new bushings if so?

Thanks again everyone for the help! I'll post up if fixing the alignment fixes the vibration.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: March-31-2019 at 2:11pm
Wow, yes that is BADLY out of alignment. I'd advise not running the boat till you get it aligned - I've read on the forum that this much of a misalignment can actually damage the shaft and/ or transmission. as far as how it got that way in the last 4 years there may be a few possibilities.   I find it difficult to believe that the isolators would cause such a drastic difference, but I suppose it's possible - Pete knows, I'm sure.   So my first question is how are your stringers?   I don't know much about your era of boat but I thought I noticed somewhere that the mounts were bolted directly to the stringers. And with the well documented stringer issues of the 70's and 70's boats..... Hopefully not, but I thought I'd throw it out there as something to check since it should be an easy visual confirmation.
I haven't replaced just the mounts, but was in fact going to do this before I ended up pulling the entire thing for a new long block. It shouldn't be too difficult, if necessary. Seems like there's a reasonable amount of room to get around in your era of boat.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: March-31-2019 at 2:17pm
Originally posted by 1989SN2001 1989SN2001 wrote:

,
Anyway, I am assuming this bad of a misalignment is basically trying to put a curve on the propshaft which would make it whip and vibrate like hell as the revs come up.

Thanks again everyone for the help! I'll post up if fixing the alignment fixes the vibration.

TJ,
The prop shaft is pretty ridgid and not very flexible so I'm not too sure about your whipping idea. I have always found that with misalignment and the shaft being in a bind that it actually snubs vibration. Yes, get the mounts in, an alignment done and post back at what happens. Get the dial indicator out and check the shaft especially aft of the strut. Don't rely on the turn the shaft 360 method. Did you get a chance to check the damper plate?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote SNobsessed Quote  Post ReplyReply Direct Link To This Post Posted: March-31-2019 at 2:25pm
As I recall, 89 would have an aluminium engine cradle, so you might want to check that for cracks & such.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: March-31-2019 at 6:51pm
Originally posted by 1989SN2001 1989SN2001 wrote:

Well I have gone through and fixed a number of problems and the engine is now running excellent. All new gaskets in the carb, and new base gaskets and it is running excellent. Motor stalls instantly when I pull the pcv hose off now, and I can actually get changes with the mixture screws. It seemed to want a little more timing, base set at 12-13 degrees, all in is about 36 at 3000rpm. Idling clean at 750, best throttle response it's ever had. I definitely had some internal fuel leak in the carb, o rings on the accelerator pump transfer pipe we're shot, and I think it was pulling fuel there, similarly to how a bad power valve would act. I also had an air leak between the spacer and manifold. Multiple issues were masking each other and making diagnosis extremely difficult.

However, I am still getting a lot of vibration from the propshaft on the water as soon as the rpms hit 1500 ish.   I put it in gear on the trailer with a friend spraying the Cutlass bearing, and I get the same very heavy vibration, it felt like it was going to jump off the trailer! I have disconnected the coupling from the transmission, and the vibration is gone. However, in a very crude check, it appears to be badly out of alignment at the coupling. With the flange touching on the bottom side, I have about a .040-.050" gap on the topside. The gap stays at the top when I turn the shaft, so the shaft seems straight, just not properly in line with the transmission. I also noticed that the front motor mount studs are leaning forward, as if the rubber in them is degrading and collapsing, causing the motor to pitch forward and thus the misalignment. I aligned this boat to within .003" 4 or 5 years ago, so something has changed.

Anyway, I am assuming this bad of a misalignment is basically trying to put a curve on the propshaft which would make it whip and vibrate like hell as the revs come up. Hopefully adjusting it will make the issue go away, but I do think the mounts need addressing to.

Has anyone here replaced motor mounts with the engine in the boat? I have an engine hoist to support it with.

Do I need to buy full mounts, or will the rubber isolators that DIM sells work for me? Do I need a huge press to install the new bushings if so?

Thanks again everyone for the help! I'll post up if fixing the alignment fixes the vibration.


The 12 degrees timing makes perfect sense if you want 36 degrees total since DUI probably engraved on the bottom of the housing something like " 24 degrees at 3000 rpm". Add 12 and there you go. Here's a typical picture



Guess it's another case of when you think it ignition , look at the fuel system.

Good job finding and fixing all the other issues
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: April-02-2019 at 12:18am
Today I got the alignment a lot closer, but didn't have time to really dial it in. Using feelers, I'm within .007 or so, a lot better than where it was before. There is a slight run-out in the face of the coupling on the shaft, .003-.004, so it's hard to gauge how good the alignment is and how much is shaft runout. It is a newer ARE double taper shaft, so I will pop it loose from the taper and reinstall it to see if it maybe finds a better home. If not, I will pull the shaft and have it trued up at a machine shop. Either way it is world's better than it was before. I can spin the prop with one finger again and it will continue to turn another 1/4 turn from momentum when I spin it fast.

The motor mounts straighted back up when I released the pinch bolts and started turning the jack nuts.   The rubber seems pretty solid, so I think I may put off changing the bushings for another time. After it goes in the water for the season, I will spend a day getting the alignment spot on again.

Anyway, now that I'm so much closer on the alignment, the vibration is completely gone. The boat pulls harder than it ever has, not sure if it's because of the carb finally being set up right or the ignition upgrade. With the acme 470 prop the boat would usually do about 4500-4600 RPM and about 43mph on the GPS. Didn't clock it with GPS tonight, but it was turning about 4800, so I expect that it picked up one or two mph on the top end. Mid range throttle response is much improved to. It's finally running like it should and I'm thrilled.

Is 4800 a little fast for this motor? We primarily wakeboard with this boat and run 750-900lbs of ballast, so I love the low end grunt with the 470, but maybe now with the engine running right I can step to a slightly less aggressive prop and still get the stump pulling low end that we like. We do occasionally put the boom on and do some short line footing, but not usually for more than a few 3-4 minute bursts. It doesn't see much slalom action anymore either. Thoughts?

Thanks again for all of the assistance!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: April-02-2019 at 12:43am
Originally posted by 1989SN2001 1989SN2001 wrote:

There is a slight run-out in the face of the coupling on the shaft, .003-.004, so it's hard to gauge how good the alignment is and how much is shaft runout. It is a newer ARE double taper shaft, so I will pop it loose from the taper and reinstall it to see if it maybe finds a better home. If not, I will pull the shaft and have it trued up at a machine shop.

I highly recommend lapping the taper. I have found the A.R.E. taper fit does need it.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: April-02-2019 at 2:47am
Congratulations, glad you are getting it ironed out.
4,800 RPM is not too fast. My GT40 would run up to 5,200 RPM when I had the 224 prop on it. I would not be concerned and just enjoy how well it is running.
When you are moving the engine around trying to find the sweet spot for alignment first look at the prop shaft and feel where it wants to locate, there is a sweet spot where it will rotate freely and be centered in the strut. It may not be centered in the log but being centered in the strut is most important. You will need to lift it some at the engine side to find where the sweet spot is.
Once you know where it is take a small block of 2x4 maybe 3-4" long, cut a V in the top of it to cradle the shaft. Rest it on the bottom of your boat with the V facing up. Slide it back under the shaft until the weight of the shaft starts to rest in the V. Once the shaft is in the sweet spot and the block is holding the front at that spot adjust the engine to match this point. Now the engine and shaft are both in line with the sweet spot.

Pete, I am sorry, on my ARE install I failed to lap the engine side of the shaft, I only lapped the prop to the shaft. All has been great for 4 seasons now but now you got me thinking.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: April-02-2019 at 7:20am
TJ,
Yes, it sure sounds like you found the problem. Great job.

Originally posted by 8122pbrainard 8122pbrainard wrote:

   Get the dial indicator out and check the shaft especially aft of the strut. Don't rely on the turn the shaft 360 method.

What did the dial indicator tell you?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1989SN2001 Quote  Post ReplyReply Direct Link To This Post Posted: April-02-2019 at 8:31pm
Pete,

I didn't pull the prop, but I put a dial indicator on the pilot at the very end of the shaft behind the prop after the threads and found a TIR of .004. I know this isn't as good as actually checking the taper portion, but I think this is close enough to within spec that I don't need to dig any further. Pulling the prop off a shaft that has been properly lapped can be a real hassle.

TIR in the middle of the shaft, just aft of the log, while connected to the trans is a little bit worse at .008. Again, this isn't great, but I don't think it warrants taking the shaft out and to a shop. As smoothly as it is running and as easy as the shaft is to turn, I think I'm going to put it in the water and get it aligned as best I can and run this season with it. I'm sure there are plenty of boats out there that are much much worse than this one. I'll also be checking that alignment monthly now that I've seen how much it can change over a couple of seasons.

I don't think I'm in the "going to kill my trans output shaft bearing in a few hours" range anymore. Besides, its likely been running the past 3 or 4 seasons much much worse than this.
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