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Again, this is my first engine rebuild. Blah, Blah, Blah. :laugh2:

I'm starting to think a machinist is in order regarding crankshaft, but wanted to get y'all's expert opinion first.

I checked the main bearing clearances with pastigauge. I came up with a pretty uniform gap of .004". The forward main bearing (pictured) was the smallest gap, by a little. All were torqued to 35 ft/lbs.

Also pictured is the manual I'm using. Highlighted are 2 pages that seem to give different tolerances. What's the difference between pitch and clearance? I'm at least close to the measurement described as pitch (.003 -.0039"), but way large of clearance (.0006 -.0022").

Yes, I double checked the number of 0's. Yes, I'm very confused. :grin2::grin2:: Yes, I'm thinking I need to take it to a pro, if I can find one in the Nashville area.
 

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Richard Jemison
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Clearance

You are probably getting incorrect readings from using the wrong plastigage diameter. Use the smaller version that puts .002 in the middle of the range of clearance.

If its more than .002 you should have the crank ground .010 under and use correct bearings.

The maximum target clearance should be .0015 preferably .001 on a street motor.
 

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What's the difference between pitch and clearance?
Pinch or crush clearances are used to determine the fit between the main bearing and main journal. This is probably one of the most overlooked clearances people miss when building an engine and is very critical. When the cap is torqued it should simulate a press fit of the bearing.

Clearance is what you measured in your picture and is simply the clearance between the crank journal and main bearing.

Alfar7 is spot on with the plastigage. Using the Clevite brand you should be using the green plastigage.
 

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Discussion Starter #4
Thanks guys! Yup. User error. I rechecked the gaps with the green plastigage and all were between .001" and .0015". So I think I'm good. Thanks for the clarification ljayr. And now I search threads for how to polish CS journals. :)
 

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Richard Jemison
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Thanks Richard. I've viewed that post many times. I haven't read it cover to cover but I will. No, I don't have the knowledge. I come here to GAIN knowledge. And, hopefully someday, share the knowledge I've gained. Until then, I'll suck up all the knowledge I can. It's the only way I see how to get this car running.
 

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I come here to GAIN knowledge. And, hopefully someday, share the knowledge I've gained. Until then, I'll suck up all the knowledge I can. It's the only way I see how to get this car running.
You have come to the right place.

Ask a question and I have no doubt you will get an answer. If you dont understand the answer ask again and again and again until you do.

Dont get frustrated when something gets you down, its an unbelievably satisfying achievement when you start her up and go for your first ride after the build.

Good luck,

Vin
 

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Thanks Vin! Looking forward to that glorious day, and the learning experience from all the missteps along the way. Although I hope they are few. :)
 

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Discussion Starter #9
Block is at a machinist that I tracked down via AROC. He's rebuilt at least 5 Alfa engines. I think it's in good hands. And, yeah, once I tore it down to the crank, it really got over my head. I'm glad I turned that critical part over to a pro.
 
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