Source of knock found!

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John bevardos
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Source of knock found!

Post by John bevardos » Sat Sep 28, 2019 7:31 pm

OK Model T brothers and sisters, with a good advice from Hank in Tennessee, I checked the wrist pin bolts for my knock, and they were all tight. I started probing further and I noticed some Babbitt coming off the thrust surfaces of the connecting rods. So it turns out I have 3 connecting rods where, due to improper tinning, all the Babbitt bearings spun inside the connecting rods. I have mic the crank and it checks out at 1.243 to 1.245. Should I get standard connecting rods and take the shims out or should I get .010 over and try and scrape the bearings. As always all advice is welcome. Thank you, John


Henry K. Lee
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Re: Source of knock found!

Post by Henry K. Lee » Sat Sep 28, 2019 8:22 pm

Oh Crap John, not good for the home team! Well it could have been worst. glad you found it.

Hank


Les Schubert
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Re: Source of knock found!

Post by Les Schubert » Sat Sep 28, 2019 8:44 pm

John
Considering the time of year, here is my thoughts
The crank is quite likely out of round.
So remove the crank and get it ground. Probably should be no problem cleaning up at .020 undersize
.020 rods should be easy to get

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TonyB
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Re: Source of knock found!

Post by TonyB » Sat Sep 28, 2019 9:22 pm

Our local babbitt company, Antique Engines in Escondido currently recommend against using newly babbitted rods if the crank is out of round by more that half a thou. ☹️
Tony Bowker
Ramona, California
1909 Touring, 1914 Touring, 1915 Speedster, 1924 Coupe.


Topic author
John bevardos
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Location: Los Angeles

Re: Source of knock found!

Post by John bevardos » Sat Sep 28, 2019 10:24 pm

Forgot to add....looks like a recent rebuild...all looks new inside and has all shims in rods and mains...all was fine until this... :|


philip
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Re: Source of knock found!

Post by philip » Sun Sep 29, 2019 6:56 am

I would mic. The crank good and it is round send the rods off with the measurements and get the
Custom poured. Philip

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John Warren
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Re: Source of knock found!

Post by John Warren » Sun Sep 29, 2019 9:39 am

I have rounded up cranks using emery cloth, more of an emergency repair or get you by for a while. Another thing to check is barreling of the journals, this is where the crank pins are fatter in the middle. This is caused from twisted rods. Just wondering if the same guy did the main bearings.( not tinning them correctly) As Les said getting it ground is best! I thought about getting one ground and decided bite the bullet an to put a new Scatt crank in. If you decide to pull the crank, It will also give you a chance to make sure the 4th main is done correctly ( check and or straighten the pan ). We all have been there. With all this said, most of the T engines don't run much or hard, so depending on how you intend to use the T, directly dictates how you should repair it. I use my cars a lot and don't want to worry about taking it on a run. Good luck in what ever you decide.
24-28 TA race car, 26 Canadian touring, 25 Roadster pickup, 14 Roadster, and 11AB Maxwell runabout
Keep it simple and keep a good junk pile if you want to invent something :P

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