Let's Play "What's that sound?"

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Thorlick
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Let's Play "What's that sound?"

Post by Thorlick » Sat Jun 29, 2019 11:33 pm

I pulled my engine out to correct a problem with main bearing shims and to replace #1 rod which has wiped it's bearings. After removing the pistons I spun the crankshaft and got quite a surprise. It made an interesting noise I have never heard before. I think I know what it is and will open the front end tomorrow and find out.

The engine was pulled due to losing the babbit in #1 and creating a horrendous rod knock. When I got it home I found the rod problem right away and then spotted some other problems resulting in engine removal. The sound is definitely not from the transmission or valves. It happens with the crank turned in either direction and seems to be at the same spot every time at 180 crankshaft degrees or 90 camshaft degrees apart!

Click on this link to hear the sound: https://youtu.be/vABzsTLALJM

I'll add more information if requested or after I open the cam gear cover to see what it is. Cryptic hint, I think it is due to a problem with an after-market oil accessory!

TH
Terry Horlick, Penn Valley, (Northern) CA
1927 Mountain Patrol Vehicle from the Los Angeles City Fire Department (L.A.F.D.)
1912 Omnibus project


Kerry
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Re: Let's Play "What's that sound?"

Post by Kerry » Sun Jun 30, 2019 1:06 am

Your cam gears are up the creek, they are out of alignment, either the nut has wound of some or the bearing for the cam end play is flogged out. the clicking is the gear teeth clearance, lash, fighting the valve springs.

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Thorlick
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Re: Let's Play "What's that sound?"

Post by Thorlick » Sun Jun 30, 2019 10:00 am

Frank,

Thanks for pointing me to cam end lash. That makes sense. It sounds like the noise is pointing to a worn out front cam bearing. The screw which keeps it in place is under the cracked generator housing which has to come off anyhow.

This seems to be a Ford point of failure. I once had a 1990's F150 which ran terribly. You would tune it up and after a few seconds it would run terribly, intermittently. The ford dealer swapped out parts like the distributor board and other bits for a $900 parts bill. Eventually I found a cracked cam cover. Inside the cam had a keeper held by two bolts. One ear was broken allowing end play on the cam. In use the cam would wander front to back (eventually breaking the cover to allow diagnosis). When it wandered forward the helical gears threw the valves out of time due to the helical pitch of the timing gears. When it wandered back into place it ran sweetly. A two bit thrust plate fixed the F150!

If you are right (and it is highly likely you are) I should be able to detect a cam jump when the noise occurs by putting a dial gauge on the flapper end of the cam. That is my next step. If that's the problem (note that I have helical timing gears on this 1927 engine) I hope my spare front cam bearing fits and is not worn out!

So testing cam end play is my next step. Later today I will explain the oil accessory red herring. I am thinking that the wandering cam fault in my F150 is a design problem inherited from the Model T cam gear design!

TH
Terry Horlick, Penn Valley, (Northern) CA
1927 Mountain Patrol Vehicle from the Los Angeles City Fire Department (L.A.F.D.)
1912 Omnibus project

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Thorlick
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Re: Let's Play "What's that sound?"

Post by Thorlick » Sun Jun 30, 2019 2:57 pm

Here is a quick video demonstrating that:
  • The clicking is not due to cam bearing wear
    The noise is due to excessive gear lash
Click here: https://youtu.be/vpPVIn-lmyM

The cam shaft is too far from the crankshaft. It was either line bored like that or worn to that condition.

The solution is... scary to contemplate.

TH
Terry Horlick, Penn Valley, (Northern) CA
1927 Mountain Patrol Vehicle from the Los Angeles City Fire Department (L.A.F.D.)
1912 Omnibus project

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Thorlick
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Re: Let's Play "What's that sound?"

Post by Thorlick » Sun Jun 30, 2019 10:04 pm

I seem to be posting to myself. I hope someone who is cam knowledgeable reads and answers this.

First the oil modification mention: When I build up a T engine I add rod scoops to help oil the bearings. This is similar to what Chevrolet did and is a debatable modification. I use the commercially available tin scoops and drill the rod cap. The first thing I do is to gently (?) widen the opening and squash the height down. The goal is to increase the cross sectional area of the scoop and decrease the height. The idea is to move more oil and be able to clear the "Horlick Mountain Pan dips" I usually utilize.

I lost the bearing on #1 rod because it is a long steep uphill drive in to town and for the first time in about 18 years I've been running without my pan dams. I have no additional oil lines at this time going stock some time ago. If I pull off the flywheel I will probably add a second interior oil line.The dip on #1 was intact.

Oil scoop spread and ready for service
oil scoop
oil scoop
`

I noted that the scoop on #3 had failed. It had sheared off where the scoop passes through it's base.
broken scoop
broken scoop


I have no Idea when the scoop came apart nor where it went. At first I naively thought it was involved in the clicking noise. I hope to find it in the t-cup at the bottom of the pan when I look there.

I have now found two problems with the scoops. First is that when you reshape them the chrome plating flakes off into your oil (and bearings). Second, now, the scoop can be weakened and caused to fail. My next set of scoops will get annealed to remove the plating and allow reshaping without cracking. Next they will be annealed again before installation.

Enough on scoops.

Now more on the noisy timing gears. I will move heaven and earth to avoid having to re-babbit and line bore my block. I have investigated and found listing for a .005 oversize timing gear at Macs and Langs. They are aluminum which I like. I would prefer bronze. This may solve or improve upon my current timing gear situation. I just don't know how to measure the clearance I have to tell if this is the way to go. Hopefully Erik Barrett will know. I assume I can get some .005 shim stock and cut a strip and see if it can be run through the gears to see if enough space exists.

In addition I have found nylon gears. I guess that is about a step down from fiber gears. The Nylon gears don't say oversize but they do say they are 7.5 degree advanced to give more slow speed torque... something my car can use. I also want to try this out since my Omnibus will need lots of low end torque to move the ponderous body around.

My thought is to get an Aluminum gear and re-drill it. I would then mark a new timing tooth at 7.5 degree advanced.

So this is what I need to know:
  • How can one tell what oversize will be needed in a cam gear?
  • Is the nylon gear available oversize?
  • If one wishes to boost low end torque, how much advance is prudent, Is there a chart or web page which explains this approach?
Gratitude in advance, TH
Terry Horlick, Penn Valley, (Northern) CA
1927 Mountain Patrol Vehicle from the Los Angeles City Fire Department (L.A.F.D.)
1912 Omnibus project


Scott_Conger
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Re: Let's Play "What's that sound?"

Post by Scott_Conger » Mon Jul 01, 2019 11:12 pm

1. I think it may be premature to assume the crank/cam distance is wrong or that an oversize cam gear will fix anything. You may just have very worn gear(s). Oversize gears are purchased to compensate for a worn crank gear, wrong line bore dimension, etc. I don't think you know the root cause to the excessive clearance and thus should not jump to a conclusion/solution that is entirely wrong for your situation. My solution in my shop would be to measure the distance between the cam and crank, add 1/2 the diameter of both parts and find out for SURE if the crank/cam distance is botched. If it is OK or reasonably close, a new set of gears from Dan McEachern would be on my order sheet that same day

2. Yes, I believe they are, and I think most users are pleased with their durability. I have never run one.

3. Time and again, 7 1/2 degrees has been found to give improved performance while retaining smooth operation. It is best to know WHO'S cam it is, and WHAT GRIND it is. Chaffin's performance cams have advance already built into them and you DON'T want to use an advance gear with some of their cams. Stipe cams don't have advance built into them and perform nicely with 7 1/2 degree advance.

Best of luck
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!


Norman Kling
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Re: Let's Play "What's that sound?"

Post by Norman Kling » Tue Jul 02, 2019 10:45 am

You mention a "cracked generator housing". What caused the crack? Could it either be caused by gear misalignment, or be the cause of gear misalignment? Also, how is the number 1 main bearing? Could be cause of the rod scoop breaking if the crankshaft was pushed down in front. Almost sounds as though you might need to do a complete rebuild.
Norm


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Re: Let's Play "What's that sound?"

Post by Billy Vrana » Tue Jul 02, 2019 1:42 pm

Pull the cam and check it between two dead centers on a lathe. Use a dial indicator on the middle bearing surface. I had one sound just like that, it was bent about 25 thou in the center


Jerry VanOoteghem
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Re: Let's Play "What's that sound?"

Post by Jerry VanOoteghem » Thu Jul 04, 2019 8:56 pm

It seems that before the #1 rod went bad, you had no idea that your timing gear backlash was excessive or a problem. That being the case, I would install a new timing gear, a rebabitted #1 rod, and go for a ride with no more thoughts of timing gear spacing or backlash. Generally speaking, unless you're looking for Montana 500 performance, a little extra backlash is no big deal. Had way too much backlash my '21 Roadster for years. It made a little extra noise, but never was a problem. Had it fixed when the engine came out for other work. Bottom line: Don't overthink this.


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Re: Let's Play "What's that sound?"

Post by Scott_Conger » Thu Jul 04, 2019 9:13 pm

Jerry

Amen
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!

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Thorlick
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Re: Let's Play "What's that sound?"

Post by Thorlick » Fri Jul 05, 2019 4:19 pm

Norman, You can see the crack in the generator housing on the right in this photo. The spare housing I have is on the left.

Generator housing
Generator housing

You can see that debris or oil in the housing bolt hole can cause a crack due to hydraulic pressurization in the closed hole design. My spare cover had the hole drilled so it is open in the rear. I think this will prevent a future crack.



Billy,

I have to pull the cam out to replace the gear, testing on centers is pretty easy to do then.



Jerry,

That is indeed my plan, in addition to having Erik take a look at it when he bores me a new rod.

TH
Terry Horlick, Penn Valley, (Northern) CA
1927 Mountain Patrol Vehicle from the Los Angeles City Fire Department (L.A.F.D.)
1912 Omnibus project


wayne sheldon
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Re: Let's Play "What's that sound?"

Post by wayne sheldon » Sat Jul 06, 2019 1:58 am

I have run many miles with knocking timing gears. I got to where I enjoyed people telling me "I hear a knock!" And me just replying "Eh its just a timing gear."
Those old steel gears can run a ridiculously long time clattering like crazy. I need to look deep in my junk to see if I can find a gear I took out of an engine almost fifty years ago. I kept it partly because it is almost unbelievable it came out of a running engine. I can only imagine how it must have sounded before they quit running the thing.

I would enjoy showing it to you Terry!

Scott C and Jerry V O have given good advice on timing, cams, and gear fitting. I have used paper run through the gears to get a feel for how tight they are, and how well they are meshing. If the gears are too close together, you must be very careful with oversize gears. If they are too far apart? There are two types of oversize gears. I don't know if both are still available or not. One type has a slightly larger diameter (we are talking thousandths of an inch!), the other has the standard diameter, both have slightly (again thousandths of an inch) wider (thicker?) teeth. One type is designed to accommodate a slightly mis-bored main bearing, the other to compensate for tooth wear using original used crank gears. This is where you need to figure just what the issue is before ordering parts.
For what it is worth department. I know some years ago, that someone ordered a custom undersize gear to fit in a slightly mis-bored mains problem. I want to say it was Dan McE that made the gear, but I am not certain of that. I remember that the gear had to be custom made, and Dan McE is among the best in that department.

For general interest. Reading the paper run through the gears is a bit of an art, and a science. The thickness of the paper must be considered. How sharp the folds are, and any cuts into the paper must all be considered. Similar paper methods are used in setting the gears in the rear end. However the rear end requires greater clearances, and the readings are slightly different.

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Thorlick
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Joined: Sun Jan 06, 2019 7:17 pm
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Re: Let's Play "What's that sound?"

Post by Thorlick » Mon Jul 08, 2019 2:33 pm

It gets worse! Well it doesn't really get worse, it was already worse and looking at the problem discloses more!

Click the following link to view. First I show the gear lash and then immediately following I show the crankshaft end play.

https://www.youtube.com/watch?v=JFtBPpl ... e=youtu.be

I will be visiting Erik soon to determine if a new bearing cap will Bandaid the problem or if my simple rod replacement has morphed into an engine block bearing re-pour. I guess a valve job might as well happen.

YIKES!!! TH
Terry Horlick, Penn Valley, (Northern) CA
1927 Mountain Patrol Vehicle from the Los Angeles City Fire Department (L.A.F.D.)
1912 Omnibus project

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