Mystery 85.5 Motor

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friedman
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Mystery 85.5 Motor

Post by friedman » Fri Nov 09, 2018 10:28 am

I posted before on a motor I'm rebuilding for a friend. This is the one that had a stuck piston. Piston is out, stuck rings removed from the piston and stuck piston bore cleaned and honed ( don't worry we honed all four bores) so we can still use the stock pistons. I thought we were done with mysteries when my mechanic buddy picks up a main bearing that fell on the floor of the shop, looks at the back side and announces that the motor has first over crank bearings since it had 010 stamped on the back. What's really scary is I would never have checked for this and put standard bearings in. The mystery gets more confusing as I look at a rod bearing and it says 020 and it's from a different manufacturer. I gather the motor would not have come from the factory with different size main bearings and non of them standard.

Next step is to go to my machinist and have him measure the crank to find out what the hell is going on.

Told my wife that this is why I don't like doing stuff like this for others but she told me to calm down, if this was my own motor I'd be going through the same steps and she is right.
Carl in Virginia
80 spider
86 Bertone
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engineerted
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Re: Mystery 85.5 Motor

Post by engineerted » Fri Nov 09, 2018 12:00 pm

Carl, listen to your wife, she is always right. :D Typically if a crank is ground down they will mark the crankshaft also. look for a metal stamping marks on one of the counter weights and or near the crank pins. Photos, we like photos!!
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friedman
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Pictures

Post by friedman » Fri Nov 09, 2018 1:36 pm

Ted, I looked but saw nothing that looked like non-factory markings. I took a bunch of pictures and readily admit I don't know if this is all factory looking or not. I do plan to get someone to look at the crank next week.
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Carl in Virginia
80 spider
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SimcaBertone66
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Re: Mystery 85.5 Motor

Post by SimcaBertone66 » Fri Nov 09, 2018 5:15 pm

Now that ya got the piston out and the holes honed, put the crank back in and see how it spins, if you are really adventurous , get some plastigage and see what you get when you torque up the mains and spin it … it may not need any attention at all.
Joe DeGasperis
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Re: Mystery 85.5 Motor

Post by fiatrn » Fri Nov 09, 2018 5:41 pm

It is ok that the Mains are .010 and the Rod bearings are .020. This is not a problem, they can wear differently.

Just check to make sure that the bearing surfaces are good and happy, and then buy the correct size rod bearings (by measuring as Simca Joe suggests (or have your machine shop measure)) and all will be fine.

While you are there, replace the bearings for the aux shaft.
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Re: Mystery 85.5 Motor

Post by davedecker4 » Sat Nov 10, 2018 1:02 am

Yep. Seconded. These cars ain't new. and were often abused when they were. I never assume that the odo hasn't been around once, or that somebody has never been in the engine before. I always check. Its easy and cheap insurance
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friedman
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Re: Mystery 85.5 Motor

Post by friedman » Sat Nov 10, 2018 8:29 am

I threw half the bearings out since it was clear the number four rod bearings were showing wear and would need to be replaced anyway. This little adventure is teaching me a lot and I have rebuilt many spider motors.
Carl in Virginia
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Re: Mystery 85.5 Motor

Post by vandor » Sun Nov 11, 2018 5:43 pm

The question is if the crank has been re-hardened after it was ground. Supposedly 2L cranks have very thin hardening which gets ground off when the crank is turned.
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friedman
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Re: Mystery 85.5 Motor

Post by friedman » Tue Nov 13, 2018 12:10 pm

Took the crank to the machinist, this guy does only crankshaft work, nothing else and came highly recommended. He confirmed the crank bearings are 10 over and rod bearings are 20 over. He said this is not unusual. He did indicate the journals need a little polishing which he is doing for me.

The only headache is getting a crank bearing set with different sized crank and rod bearings as the vendors usually sell them in complete one size sets.
Carl in Virginia
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Re: Mystery 85.5 Motor

Post by SimcaBertone66 » Tue Nov 13, 2018 12:32 pm

Good work, excellent that the crank is good … … vendors, spenders, thy should be available as individual main or rod bearing sets ? Have fun …
Joe DeGasperis
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