crankshaft machining error question for engine builders

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dbphemi

dbphemi

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So i just measured my crankshaft main and rod journals to check for wear and taper .I’m doing a light rebuild with new bearings and rings and seals. I had this crank machined decades ago when i was in high school by a machine shop that is no longer in business. the rods are .030 under and the mains are supposed to be .020 under.
i measured the rods and they are 2.095 which is .030 under the stock spec of 2.125.
I measured the mains a they are 2.4802 . It should read 2.480 at .020 undersized. is .0002 over going to be a problem?
I haven’t measured bearing clearance yet , I'm in the cleaning phase right now but i’d like to know if i need to have things machined.
Thanks!
 
Do you have high quality measuring tools?

.0002 is nothing, margin of error in the tool or methods could be more than that.
 
Hell, they machined it in unheated shop in winter and you measured it in a heated garage can cause that.

That's nothing. Carry on.
 
i have fowler micrometers . i wouldn’t call them high end but they allowed me to use them in the aircraft department of the bearing factory i used to work in. lol
 
My 273 I built 10 years ago was the first engine I didn't use Plastigage on. (I just measured and calculated the oil clearance. ) Get some Plastigauge and check it out.
 
dbphemi said:
So i just measured my crankshaft main and rod journals to check for wear and taper .I’m doing a light rebuild with new bearings and rings and seals. I had this crank machined decades ago when i was in high school by a machine shop that is no longer in business. the rods are .030 under and the mains are supposed to be .020 under.
i measured the rods and they are 2.095 which is .030 under the stock spec of 2.125.
I measured the mains a they are 2.4802 . It should read 2.480 at .020 undersized. is .0002 over going to be a problem?
I haven’t measured bearing clearance yet , I'm in the cleaning phase right now but i’d like to know if i need to have things machined.
Thanks!
Click to expand...



.0002 is fine. Get the mains at .0023-.0025 and the rods at .0021-.0023 and send it.
 
jos51700 said:
Hell, they machined it in unheated shop in winter and you measured it in a heated garage can cause that.

That's nothing. Carry on.
Click to expand...
Read this ^^^^ over and over and then some more.
 
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