BBC rod bearing clearance

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Abbottracingheads
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Re: BBC rod bearing clearance

Post by Abbottracingheads »

I do not see you getting an accurate measurement with dial calipers in this case. Take it to someone with the right equipment and get it checked.
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Bishop540
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Re: BBC rod bearing clearance

Post by Bishop540 »

Bishop540 wrote: ↑Tue Sep 25, 2018 2:10 pm
The attached picture was a plastigage I did with the new King X. But it wasnt a pretty test. Not sure why the plastigage didn't flatten in the middle. ????
I know exactly why all the plastigage didnt flatten in the center: I had ordered the wrong bearings. I ordered the bearings for an aluminum rod, one that has the dowel hole in it. But I was told I could use them with my steel rod. I also researched here and abroad that many different engine builders have done this before too.

I also didnt have 2 rods on the journal before I torqued the bolts. The cap may have moved around a bit and not flattened correctly. The next post will be plastigage with 2 rods side by side:
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MadBill
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Re: BBC rod bearing clearance

Post by MadBill »

It looks like the PG at the bottom of the pic is showing more like 0.0010-0.0015" gap vs. 0.0020" at the top! When you re-do it with both rods, put snug-fitting feeler gauges between the rods JIC, to prevent twist.
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Bishop540
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Re: BBC rod bearing clearance

Post by Bishop540 »

This is just an idea of my .003 measurement that I came up with, measured with plastigage. 2 rods side by side. This measurement doesnt show .003 unless you are suppose to double the measurement for the other side....I know its not an accurate measurement but it is a little offcenter, since the dowel hole (non smashed plastigage) isnt shown in the plastigage.
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Last edited by Bishop540 on Tue Sep 25, 2018 4:35 pm, edited 1 time in total.
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Re: BBC rod bearing clearance

Post by Bishop540 »

MadBill wrote: ↑Tue Sep 25, 2018 4:30 pm It looks like the PG at the bottom of the pic is showing more like 0.0010-0.0015" gap vs. 0.0020" at the top! When you re-do it with both rods, put snug-fitting feeler gauges between the rods JIC, to prevent twist.
Great idea. I didnt even do that this time. But i did measure it with a .015 feeler gauge. But didnt think about leaving it there when i torqued the caps. Now I am out of plastigage.......
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Re: BBC rod bearing clearance

Post by Warp Speed »

Get more plasti-gauge and play with it until you can get consistent results. It is WAY better than the dial caliper and math method you started with!
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